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  • How do you save and retrieve a Key/IV pair securely?

    - by Shawn Steward
    I'm using VB.Net's RijndaelManaged (RM) to encrypt files, using the RM.GenerateKey and RM.GenerateIV methods to generate the Key and IV and encrypting the file using the CryptoStream class. I'm planning on saving this Key and IV to a file and want to make sure I'm doing it the right way. I am combining the IV+Key, and encrypting that with my RSA Public key and writing it out to a file. Then, to decrypt I use the RSA Private key on this file to get the IV+Key, split them up and set RM.Key and RM.IV to these values and run the decryptor. Is this the best method to accomplish this, or is there a preferred method for saving the IV & Key? Also, what's the best way to construct and deconstruct the byte array? I used the .Concat method to join them together and that seems to work well but I can't seem to find something as easy to deconstruct it. I played with the .Take method that takes the first x # of bytes and it works for the first part but can't find anything that gets the rest of it.

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  • Call to a member function num_rows() on a non-object

    - by Patrick
    I need to get the number of rows of a query (so I can paginate results). As I'm learning codeigniter (and OO php) I wanted to try and chain a -num_rows() to the query, but it doesn't work: //this works: $data['count'] = count($this->events->findEvents($data['date'], $data['keyword'])); //the following doesn't work and generates // Fatal Error: Call to a member function num_rows() on a non-object $data['count2'] = $this->events->findEvents($data['date'], $data['keyword'])->num_rows(); the model returns an array of objects, and I think this is the reason why I can't use a method on it. function findEvents($date, $keyword, $limit = NULL, $offset = NULL) { $data = array(); $this->db->select('events.*, venues.*, events.venue AS venue_id'); $this->db->join('venues', 'events.venue = venues.id'); if ($date) { $this->db->where('date', $date); } if ($keyword) { $this->db->like('events.description', $keyword); $this->db->or_like('venues.description', $keyword); $this->db->or_like('band', $keyword); $this->db->or_like('venues.venue', $keyword); $this->db->or_like('genre', $keyword); } $this->db->order_by('date', 'DESC'); $this->db->order_by('events.priority', 'DESC'); $this->db->limit($limit, $offset); //for pagination purposes $Q = $this->db->get('events'); if ($Q->num_rows() > 0) { foreach ($Q->result() as $row) { $data[] = $row; } } $Q->free_result(); return $data; } Is there anything that i can do to be able to use it? EG, instead of $data[] = $row; I should use another (OO) syntax?

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  • Problem when trying to connect to a desktop server from android on wifi

    - by thiagolee
    Hello, I am trying to send a file from the phone running Android 1.5 to a server on a desktop. I wrote some code, which works on emulator, but on the phone it doesn't. I'm connecting to the network through WiFi. It works, I can access the internet through my phone and I've configured my router. The application stops when I'm trying to connect. I have the permissions. Someone have any ideas, below is my code. Running on Android package br.ufs.reconhecimento; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.net.Socket; import android.app.Activity; import android.app.AlertDialog; import android.content.DialogInterface; import android.content.Intent; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.EditText; import android.widget.ImageButton; /** * Sample code that invokes the speech recognition intent API. */ public class Reconhecimento extends Activity implements OnClickListener { static final int VOICE_RECOGNITION_REQUEST_CODE = 1234; static final String LOG_VOZ = "UFS-Reconhecimento"; final int INICIAR_GRAVACAO = 01; int porta = 5158; // Porta definida no servidor int tempoEspera = 1000; String ipConexao = "172.20.0.189"; EditText ipEdit; /** * Called with the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Inflate our UI from its XML layout description. setContentView(R.layout.main); // Get display items for later interaction ImageButton speakButton = (ImageButton) findViewById(R.id.btn_speak); speakButton.setPadding(10, 10, 10, 10); speakButton.setOnClickListener(this); //Alerta para o endereço IP AlertDialog.Builder alerta = new AlertDialog.Builder(this); alerta.setTitle("IP");//+mainWifi.getWifiState()); ipEdit = new EditText(this); ipEdit.setText(ipConexao); alerta.setView(ipEdit); alerta.setMessage("Por favor, Confirme o endereço IP."); alerta.setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { ipConexao = ipEdit.getText().toString(); Log.d(LOG_VOZ, "Nova Atribuição do Endreço IP: " + ipConexao); } }); alerta.create(); alerta.show(); } /** * Handle the click on the start recognition button. */ public void onClick(View v) { if (v.getId() == R.id.btn_speak) { //startVoiceRecognitionActivity(); Log.d(LOG_VOZ, "Iniciando a próxima tela"); Intent recordIntent = new Intent(this, GravacaoAtivity.class); Log.d(LOG_VOZ, "Iniciando a tela (instancia criada)"); startActivityForResult(recordIntent, INICIAR_GRAVACAO); Log.d(LOG_VOZ, "Gravação iniciada ..."); } } /** * Handle the results from the recognition activity. */ @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { Log.d(LOG_VOZ, "Iniciando onActivityResult()"); if (requestCode == INICIAR_GRAVACAO && resultCode == RESULT_OK) { String path = data.getStringExtra(GravacaoAtivity.RETORNO); conexaoSocket(path); } else Log.e(LOG_VOZ, "Resultado Inexperado ..."); } private void conexaoSocket(String path) { Socket socket = SocketOpener.openSocket(ipConexao, porta, tempoEspera); if(socket == null) return; try { DataOutputStream conexao = new DataOutputStream(socket.getOutputStream()); Log.d(LOG_VOZ, "Acessando arquivo ..."); File file = new File(path); DataInputStream arquivo = new DataInputStream(new FileInputStream(file)); Log.d(LOG_VOZ, "Iniciando Transmissão ..."); conexao.writeLong(file.length()); for(int i = 0; i < file.length(); i++) conexao.writeByte(arquivo.readByte()); Log.d(LOG_VOZ, "Transmissão realizada com sucesso..."); Log.d(LOG_VOZ, "Fechando a conexão..."); conexao.close(); socket.close(); Log.d(LOG_VOZ, "============ Processo finalizado com Sucesso =============="); } catch (IOException e) { Log.e(LOG_VOZ, "Erro ao fazer a conexão via Socket. " + e.getMessage()); // TODO Auto-generated catch block } } } class SocketOpener implements Runnable { private String host; private int porta; private Socket socket; public SocketOpener(String host, int porta) { this.host = host; this.porta = porta; socket = null; } public static Socket openSocket(String host, int porta, int timeOut) { SocketOpener opener = new SocketOpener(host, porta); Thread t = new Thread(opener); t.start(); try { t.join(timeOut); } catch(InterruptedException e) { Log.e(Reconhecimento.LOG_VOZ, "Erro ao fazer o join da thread do socket. " + e.getMessage()); //TODO: Mensagem informativa return null; } return opener.getSocket(); } public void run() { try { socket = new Socket(host, porta); }catch(IOException e) { Log.e(Reconhecimento.LOG_VOZ, "Erro na criação do socket. " + e.getMessage()); //TODO: Mensagem informativa } } public Socket getSocket() { return socket; } } Running on the desktop Java: import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket; public class ServidorArquivo { private static int porta = 5158; static String ARQUIVO = "voz.amr"; /** * Caminho que será gravado o arquivo de audio */ static String PATH = "/home/iade/Trabalho/lib/"; public static void main(String[] args) { int i = 1; try { System.out.println("Iniciando o Servidor Socket - Android."); ServerSocket s = new ServerSocket(porta); System.out.println("Servidor Iniciado com Sucesso..."); System.out.println("Aguardando conexões na porta: " + porta); while(true) { Socket recebendo = s.accept(); System.out.println("Aceitando conexão de nº " + i); new ThreadedHandler(recebendo).start(); i++; } } catch (Exception e) { System.out.println("Erro: " + e.getMessage()); e.printStackTrace(); } } } class ThreadedHandler extends Thread { private Socket socket; public ThreadedHandler(Socket so) { socket = so; } public void run() { DataInputStream entrada = null; DataOutputStream arquivo = null; try { entrada = new DataInputStream(socket.getInputStream()); System.out.println("========== Iniciando a leitura dos dados via Sockets =========="); long tamanho = entrada.readLong(); System.out.println("Tamanho do vetor " + tamanho); File file = new File(ServidorArquivo.PATH + ServidorArquivo.ARQUIVO); if(!file.exists()) file.createNewFile(); arquivo = new DataOutputStream(new FileOutputStream(file)); for(int j = 0; j < tamanho; j++) { arquivo.write(entrada.readByte()); } System.out.println("========== Dados recebidos com sucesso =========="); } catch (Exception e) { System.out.println("Erro ao tratar do socket: " + e.getMessage()); e.printStackTrace(); } finally { System.out.println("**** Fechando as conexões ****"); try { entrada.close(); socket.close(); arquivo.close(); } catch (IOException e) { System.out.println("Erro ao fechar conex&#65533;es " + e.getMessage()); e.printStackTrace(); } } System.out.println("============= Fim da Gravação ==========="); // tratar o arquivo String cmd1 = "ffmpeg -i voz.amr -ab 12288 -ar 16000 voz.wav"; String cmd2 = "soundstretch voz.wav voz2.wav -tempo=100"; String dir = "/home/iade/Trabalho/lib"; File workDir = new File(dir); File f1 = new File(dir+"/voz.wav"); File f2 = new File(dir+"/voz2.wav"); f1.delete(); f2.delete(); try { executeCommand(cmd1, workDir); System.out.println("realizou cmd1"); executeCommand(cmd2, workDir); System.out.println("realizou cmd2"); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } private void executeCommand(String cmd1, File workDir) throws IOException, InterruptedException { String s; Process p = Runtime.getRuntime().exec(cmd1,null,workDir); int i = p.waitFor(); if (i == 0) { BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream())); // read the output from the command while ((s = stdInput.readLine()) != null) { System.out.println(s); } } else { BufferedReader stdErr = new BufferedReader(new InputStreamReader(p.getErrorStream())); // read the output from the command while ((s = stdErr.readLine()) != null) { System.out.println(s); } } } } Thanks in advance.

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  • joining / merging two arrays

    - by Shishant
    I have two arrays like this, actually this is mysql data retrieved from two different servers: $array1 = array ( 0 => array ( 'id' => 1, 'name' => 'somename') , 1 => array ( 'id' => 2, 'name' => 'somename2') ); $array2 = array ( 0 => array ( 'thdl_id' => 1, 'otherdate' => 'spmethings') , 1 => array ( 'thdl_id' => 2, 'otherdate' => 'spmethings22') ); how can i join / merge array so it looks like this $new_array = array ( 0 => array ( 'id' => 1, 'name' => 'somename', 'otherdate' => 'spmethings') , 1 => array ( 'id' => 2, 'name' => 'somename2', 'otherdate' => 'spmethings22') );

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  • Help Me With This Access Query

    - by yae
    I have 2 tables: "products" and "pieces" PRODUCTS idProd product price PIECES id idProdMain idProdChild quant idProdMain and idProdChild are related with the table: "products". Other considerations is that 1 product can have some pieces and 1 product can be a piece. Price product equal a sum of quantity * price of all their pieces. "Products" table contains all products (p EXAMPLE: TABLE PRODUCTS (idProd - product - price) 1 - Computer - 300€ 2 - Hard Disk - 100€ 3 - Memory - 50€ 4 - Main Board - 100€ 5 - Software - 50€ 6 - CDroms 100 un. - 30€ TABLE PIECES (id - idProdMain - idProdChild - Quant.) 1 - 1 - 2 - 1 2 - 1 - 3 - 2 3 - 1 - 4 - 1 WHAT I NEED? I need update the price of the main product when the price of the product child (piece) is changed. Following the previous example, if I change the price of this product "memory" (is a piece too) to 60€, then product "Computer" will must change his price to 320€ How I can do it using queries? Already I have tried this to obatin the price of the main product, but not runs. This query not returns any value: SELECT Sum(products.price*pieces.quant) AS Expr1 FROM products LEFT JOIN pieces ON (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdChild) AND (products.idProd = pieces.idProdMain) WHERE (((pieces.idProdMain)=5)); MORE INFO The table "products" contains all the products to sell that it is in the shop. The table "pieces" is to take a control of the compound products. To know those who are the products children. For example of compound product: computers. This product is composed by other products (motherboard, hard disk, memory, cpu, etc.)

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  • Python subprocess: 64 bit windows server PIPE doesn't exist :(

    - by Spaceman1861
    I have a GUI that launches selected python scripts and runs it in cmd next to the gui window. I am able to get my launcher to work on my (windows xp 32 bit) laptop but when I upload it to the server(64bit windows iss7) I am running into some issues. The script runs, to my knowledge but spits back no information into the cmd window. My script is a bit of a Frankenstein that I have hacked and slashed together to get it to work I am fairly certain that this is a very bad example of the subprocess module. Just wondering if i could get a hand :). My question is how do i have to alter my code to work on a 64bit windows server. :) from Tkinter import * import pickle,subprocess,errno,time,sys,os PIPE = subprocess.PIPE if subprocess.mswindows: from win32file import ReadFile, WriteFile from win32pipe import PeekNamedPipe import msvcrt else: import select import fcntl def recv_some(p, t=.1, e=1, tr=5, stderr=0): if tr < 1: tr = 1 x = time.time()+t y = [] r = '' pr = p.recv if stderr: pr = p.recv_err while time.time() < x or r: r = pr() if r is None: if e: raise Exception(message) else: break elif r: y.append(r) else: time.sleep(max((x-time.time())/tr, 0)) return ''.join(y) def send_all(p, data): while len(data): sent = p.send(data) if sent is None: raise Exception(message) data = buffer(data, sent) The code above isn't mine def Run(): print filebox.get(0) location = filebox.get(0) location = location.__str__().replace(listbox.get(ANCHOR).__str__(),"") theTime = time.asctime(time.localtime(time.time())) lastbox.delete(0, END) lastbox.insert(END,theTime) for line in CookieCont: if listbox.get(ANCHOR) in line and len(line) > 4: line[4] = theTime else: "Fill In the rip Details to record the time" if __name__ == '__main__': if sys.platform == 'win32' or sys.platform == 'win64': shell, commands, tail = ('cmd', ('cd "'+location+'"',listbox.get(ANCHOR).__str__()), '\r\n') else: return "Please use contact admin" a = Popen(shell, stdin=PIPE, stdout=PIPE) print recv_some(a) for cmd in commands: send_all(a, cmd + tail) print recv_some(a) send_all(a, 'exit' + tail) print recv_some(a, e=0) The Code above is mine :)

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  • Replacing a word in a text file with a value using python

    - by Jamde Jam
    I have been trying to replace a word in a text file with a value (say 1), but my outfile is blank.I am new to python (its only been a month since I have been learning it). My file is relatively large, but I just want to replace a word with the value 1 for now. Here is a segment of what the file looks like: NAME SECOND_1 ATOM 1 6 0 0 0 # ORB 1 ATOM 2 2 0 12/24 0 # ORB 2 ATOM 3 2 12/24 0 0 # ORB 2 ATOM 4 2 0 0 4/24 # ORB 3 ATOM 5 2 0 0 20/24 # ORB 3 ATOM 6 2 0 0 8/24 # ORB 3 ATOM 7 2 0 0 16/24 # ORB 3 ATOM 8 6 0 0 12/24 # ORB 1 ATOM 9 2 12/24 0 12/24 # ORB 2 ATOM 10 2 0 12/24 12/24 # ORB 2 #1 #2 #3 I want to first replace the word ATOM with the value 1. Next I want to replace #ORB with a space. Here is what I am trying thus far. input = open('SECOND_orbitsJ22.txt','r') output=open('SECOND_orbitsJ22_out.txt','w') for line in input: word=line.split(',') if(word[0]=='ATOM'): word[0]='1' output.write(','.join(word)) Can anyone offer any suggestions or help? Thanks so much.

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  • Retrieve only the superclass from a class hierarchy

    - by user1792724
    I have an scenario as the following: @Entity @Table(name = "ANIMAL") @Inheritance(strategy = InheritanceType.JOINED) public class Animal implements Serializable { @Id @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "S_ANIMAL") @SequenceGenerator(name = "S_ANIMAL", sequenceName = "S_ANIMAL", allocationSize = 1) public int getNumero() { return numero; } public void setNumero(int numero) { this.numero = numero; } . . . } and as the subclass: @Entity @Table(name = "DOG") public class Dog extends Animal { private static final long serialVersionUID = -7341592543130659641L; . . . } I have a JPA Select statement like this: SELECT a FROM Animal a; I'm using Hibernate 3.3.1 As I can see the framework retrieves instances of Animal and also of Dog using a left outer join. Is there a way to Select only the "part" Animal? I mean, the previous Select will get all the Animals, those that are only Animals but not Dogs and those that are Dogs. I want them all, but in the case of Dogs I want to only retrieve the "Animal part" of them. I found the @org.hibernate.annotations.Entity(polymorphism = PolymorphismType.EXPLICIT) but as I could see this only works if Animal isn't an @Entity. Thanks a lot.

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  • Will Apple bundle the Mono Touch runtime with every iPhone?

    - by Zoran Simic
    It strikes me as a good idea for Apple to negotiate with Novell and bundle the Mono Touch runtime (only the runtime of course) into every iPhone and iPod Touch. Perhaps even make it a "one time install" that automatically gets downloaded from the App Store the first time one downloads an app build with Mono Touch, making every subsequent Mono Touch app much lighter to download (without the runtime). Doing so would be similar in a way to adding Bootcamp to OS X: it would make it easier for C# developers to join the party, but that wouldn't mean these developers will all stick to C#... What convinced me to buy a Mac is Bootcamp - I figured I could always install Windows if I didn't like OS X (and I liked the hardware, so no problem there). 6 months later, I'm using OS X full time... Would there be any technical issues in doing so? I see only advantages for all parties, not one disadvantage to anyone (except maybe for the few unfortunate Apple employees who would have to test the crap out of the Mono Touch runtime before bundling it): Novell wins because Mono Touch becomes much more viable (Mono Touch apps become much lighter all of the sudden) Developers win because now there's one more tool in the tool belt Many C# Developers would be very interested by this Apple wins because that would bring even more attention to the platform, more revenue in developer fees, more potential great apps, etc Users win because less space is used by different Apps having copies of the same runtime accumulating on their devices Would there be a major technical obstacle in bundling Mono Touch to iPhone OS? Edit: Changed the title from "Should" to "Will Apple bundle the runtime?", I think the consensus on predicting that means a lot to those considering going with Mono Touch.

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  • Mysql select - improve performance

    - by realshadow
    Hey, I am working on an e-shop which sells products only via loans. I display 10 products per page in any category, each product has 3 different price tags - 3 different loan types. Everything went pretty well during testing time, query execution time was perfect, but today when transfered the changes to the production server, the site "collapsed" in about 2 minutes. The query that is used to select loan types sometimes hangs for ~10 seconds and it happens frequently and thus it cant keep up and its hella slow. The table that is used to store the data has approximately 2 milion records and each select looks like this: SELECT * FROM products_loans WHERE KOD IN("X17/Q30-10", "X17/12", "X17/5-24") AND 369.27 BETWEEN CENA_OD AND CENA_DO; 3 loan types and the price that needs to be in range between CENA_OD and CENA_DO, thus 3 rows are returned. But since I need to display 10 products per page, I need to run it trough a modified select using OR, since I didnt find any other solution to this. I have asked about it here, but got no answer. As mentioned in the referencing post, this has to be done separately since there is no column that could be used in a join (except of course price and code, but that ended very, very badly). Here is the show create table, kod and CENA_OD/CENA_DO very indexed via INDEX. CREATE TABLE `products_loans` ( `KOEF_ID` bigint(20) NOT NULL, `KOD` varchar(30) NOT NULL, `AKONTACIA` int(11) NOT NULL, `POCET_SPLATOK` int(11) NOT NULL, `koeficient` decimal(10,2) NOT NULL default '0.00', `CENA_OD` decimal(10,2) default NULL, `CENA_DO` decimal(10,2) default NULL, `PREDAJNA_CENA` decimal(10,2) default NULL, `AKONTACIA_SUMA` decimal(10,2) default NULL, `TYP_VYHODY` varchar(4) default NULL, `stage` smallint(6) NOT NULL default '1', PRIMARY KEY (`KOEF_ID`), KEY `CENA_OD` (`CENA_OD`), KEY `CENA_DO` (`CENA_DO`), KEY `KOD` (`KOD`), KEY `stage` (`stage`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 And also selecting all loan types and later filtering them trough php doesnt work good, since each type has over 50k records and the select takes too much time as well... Any ides about improving the speed are appreciated.

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  • Django generic relation field reports that all() is getting unexpected keyword argument when no args

    - by Joshua
    I have a model which can be attached to to other models. class Attachable(models.Model): content_type = models.ForeignKey(ContentType) object_pk = models.TextField() content_object = generic.GenericForeignKey(ct_field="content_type", fk_field="object_pk") class Meta: abstract = True class Flag(Attachable): user = models.ForeignKey(User) flag = models.SlugField() timestamp = models.DateTimeField() I'm creating a generic relationship to this model in another model. flags = generic.GenericRelation(Flag) I try to get objects from this generic relation like so: self.flags.all() This results in the following exception: >>> obj.flags.all() Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/manager.py", line 105, in all return self.get_query_set() File "/usr/local/lib/python2.6/dist-packages/django/contrib/contenttypes/generic.py", line 252, in get_query_set return superclass.get_query_set(self).filter(**query) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 498, in filter return self._filter_or_exclude(False, *args, **kwargs) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 516, in _filter_or_exclude clone.query.add_q(Q(*args, **kwargs)) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1675, in add_q can_reuse=used_aliases) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1569, in add_filter negate=negate, process_extras=process_extras) File "/usr/local/lib/python2.6/dist-packages/django/db/models/sql/query.py", line 1737, in setup_joins "Choices are: %s" % (name, ", ".join(names))) FieldError: Cannot resolve keyword 'object_id' into field. Choices are: content_type, flag, id, nestablecomment, object_pk, timestamp, user >>> obj.flags.all(object_pk=obj.pk) Traceback (most recent call last): File "<console>", line 1, in <module> TypeError: all() got an unexpected keyword argument 'object_pk' What have I done wrong?

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  • Nhibernate - stuck with detached criteria (asp.net mvc 1 with nhibernate 2) c#

    - by Jen
    OK so I can't find a good example of this so I can better understand how to use detached criteria (assuming that's what I want to use in the first place). I have 2 tables. Placement and PlacementSupervisor My PlacementSupervisor table has a FK of PlacementID which relates to Placement.PlacementID - though my nhibernate model class has PlacementSupervisor . Placement (rather than specifically specifying a property of placement ID - not sure if this is important). What I am trying to do is - if values are passed through for the supervisor ID I want to restrict placements with that supervisor id. Have tried: ICriteria query = m_PlacementRepository.QueryAlias("p") .... if (criteria.SupervisorId > 0 && !string.IsNullOrEmpty(criteria.SupervisorTypeId)) { DetachedCriteria entityQuery = DetachedCriteria.For<PlacementSupervisor>("sup") .Add(Restrictions.And( Restrictions.Eq("sup.supervisorId", criteria.SupervisorId), Restrictions.Eq("sup.supervisorTypeId", criteria.SupervisorTypeId) )) .SetProjection(Projections.ProjectionList() .AddPropertyAlias("Placement.PlacementId", "PlacementId") ); query.Add(Subqueries.PropertyIn("p.PlacementId", entityQuery)); } Which just gives me the error: Could not find a matching criteria info provider to: (sup.supervisorId = 5 and sup.supervisorTypeId = U) Firstly supervisorTypeId is a string. Secondly I don't understand how to achieve what I'm trying to do so have just been trying various combinations of projections, and property aliases and subquery options..as I don't get how I'm supposed to join to another table/entity when the FK key sits in the second table. Can someone point me in the right direction. It seems like such an easy thing to do from a data perspective that hopefully I'm just missing something obvious!!

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  • Vector ArrayIndexOutOfBounds

    - by Esmond
    I'm having an ArrayIndexOutofBounds exception with the following code. The exception is thrown at the line where Node nodeJ = vect.get(j) but it does not make sense to me since j is definitely smaller than i and Node nodeI = vect.get(i) does not throw any exception. any help is appreciated. public static Vector join(Vector vect) throws ItemNotFoundException { Vector<Node> remain = vect; for (int i = 1; i < vect.size(); i++) { Node nodeI = vect.get(i); for (int j = 0; j < i; j++) {//traverse the nodes before nodeI Node nodeJ = vect.get(j); if (nodeI.getChild1().getSeq().equals(nodeJ.getSeq())) { nodeI.removeChild(nodeJ); nodeI.setChild(nodeJ); remain.remove(j); } if (nodeI.getChild2().getSeq().equals(nodeJ.getSeq())) { nodeI.removeChild(nodeJ); nodeI.setChild(nodeJ); remain.remove(j); } } } return remain; }

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  • NHibernate collections: many-to-many relationships

    - by Brad Heller
    I've got two models, a Product model and a ShoppingCart model. The ShoppingCart model has a collection of products as a property called Products (List). Here is the mapping for my ShoppingCart model. <class name="MyProject.ShoppingCart, MyProject" table="ShoppingCarts"> <id name="Id" column="Id"> <generator class="native" /> </id> <many-to-one name="Company" class="MyProject.Company, MyProject" column="CompanyId" /> <property name="ExternalId" column="GUID" generated="insert" /> <property name="Name" column="Name" /> <property name="Total" column="Total" /> <property name="CreationDate" column="CreationDate" generated="insert" /> <property name="UpdatedDate" column="UpdatedDate" generated="always" /> <bag name="Products" table="ShoppingCartContents" lazy="false"> <key column="ShoppingCartId" /> <many-to-many column="ProductId" class="MyProjectMyProject.Product, MyProject" fetch="join" /> </bag> </class> When I try to save to the DB, the ShoppingCart is saved, but the mapping rows in ShoppingCartContents aren't save, making me thing that there's an issue with the mapping. Where am I going wrong here?

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  • how to add a function to that program, and call that function from the command line in the function

    - by user336291
    a#include "smallsh.h" /*include file for example*/ /*program buffers and work pointers*/ static char inpbuf[MAXBUF], tokbuf[2*MAXBUF], *ptr = inpbuf, *tok = tokbuf; userin(p) /*print prompt and read a line*/ char *p; { int c, count; /*initialization for later routines*/ ptr = inpbuf; tok = tokbuf; /*display prompt*/ printf("%s ",p); for(count = 0;;) { if((c = getchar()) == EOF) return(EOF); if(count<MAXBUF) inpbuf[count++] = c; if(c == '\n' && count <MAXBUF) { inpbuf[count] = '\0'; return(count); } /*if line too long restart*/ if(c == '\n') { printf("smallsh:input line too long\n"); count = 0; printf("%s",p); } } } gettok(outptr) /*get token and place into tokbuf*/ char **outptr; { int type; *outptr = tok; /*strip white space*/ for(;*ptr == ' ' || *ptr == '\t'; ptr++) ; *tok++ = *ptr; switch(*ptr++) { case '\n': type = EOL; break; case '&': type = AMPERSAND; break; case ';': type = SEMICOLON; break; case '#': type = POUND; break; default: type = ARG; while(inarg(*ptr)) *tok++ = *ptr++; } *tok++ = '\0'; return(type); } static char special[]= {' ', '\t', '&', ':', '\n', '\0'}; inarg(c) /*are we in an ordinary argument*/ char c; { char *wrk; for(wrk = special;*wrk != '\0';wrk++) if(c == *wrk) return(0); return(1); } #include "smallsh.h" procline() /*process input line*/ { char *arg[MAXARG+1]; /*pointer array for runcommand*/ int toktype; /*type of token in command*/ int narg; /*number of arguments so far*/ int type; /*FOREGROUND or BACKGROUND*/ for(narg = 0;;) { /*loop FOREVER*/ /*take action according to token type*/ switch(toktype = gettok(&arg[narg])) { case ARG: if(narg<MAXARG) narg++; break; case EOL: case SEMICOLON: case AMPERSAND: case POUND: type = (toktype == AMPERSAND) ? BACKGROUND : FOREGROUND; if(narg!=0) { arg[narg] = NULL; runcommand(arg, type); } if((toktype == EOL)||(toktype=POUND)) return; narg = 0; break; } } } #include "smallsh.h" /*execute a command with optional wait*/ runcommand(cline,where) char **cline; int where; { int pid, exitstat, ret; if((pid = fork()) <0) { perror("smallsh"); return(-1); } if(pid == 0) { /*child*/ execvp(*cline, cline); perror(*cline); exit(127); } /*code for parent*/ /*if background process print pid and exit*/ if(where == BACKGROUND) { printf("[Process id %d]\n", pid); return(0); } /*wait until process pid exists*/ while( (ret=wait(&exitstat)) != pid && ret != -1) ; return(ret == -1 ? -1 : exitstat); } #include "smallsh.h" char *prompt = "Command>"; /*prompt*/ main() { while(userin(prompt) != EOF) procline(); }

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  • foreignkey problem

    - by realshadow
    Hey, Imagine you have this model: class Category(models.Model): node_id = models.IntegerField(primary_key = True) type_id = models.IntegerField(max_length = 20) parent_id = models.IntegerField(max_length = 20) sort_order = models.IntegerField(max_length = 20) name = models.CharField(max_length = 45) lft = models.IntegerField(max_length = 20) rgt = models.IntegerField(max_length = 20) depth = models.IntegerField(max_length = 20) added_on = models.DateTimeField(auto_now = True) updated_on = models.DateTimeField(auto_now = True) status = models.IntegerField(max_length = 20) node = models.ForeignKey(Category_info, verbose_name = 'Category_info', to_field = 'node_id' The important part is the foreignkey. When I try: Category.objects.filter(type_id = 15, parent_id = offset, status = 1) I get an error that get returned more than category, which is fine, because it is supposed to return more than one. But I want to filter the results trough another field, which would be type id (from the second Model) Here it is: class Category_info(models.Model): objtree_label_id = models.AutoField(primary_key = True) node_id = models.IntegerField(unique = True) language_id = models.IntegerField() label = models.CharField(max_length = 255) type_id = models.IntegerField() The type_id can be any number from 1 - 5. I am desparately trying to get only one result where the type_id would be number 1. Here is what I want in sql: SELECT c.*, ci.* FROM category c JOIN category_info ci ON (c.node_id = ci.node_id) WHERE c.type_id = 15 AND c.parent_id = 50 AND ci.type_id = 1 Any help is GREATLY appreciated. Regards

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  • Why rails app is redirecting unexpectedly instead of matching the route?

    - by ruevaughn
    I asked this question earlier and thought it was fixed, but it's not. Previous question here My problem is I am trying to set my routes so that when I type in localhost:3000/sites/admin It should redirect to localhost:3000/en/sites/admin here is my routes.rb file scope ":locale", locale: /#{I18n.available_locales.join("|")}/ do get "log_out" => "sessions#destroy", as: "log_out" get "log_in" => "sessions#new", as: "log_in" resources :sites, except: [:new, :edit, :index, :show, :update, :destroy, :create] do collection do get :home get :about_us get :faq get :discounts get :services get :contact_us get :admin get :posts end end resources :users resources :abouts resources :sessions resources :coupons resources :monthly_posts resources :reviews resources :categories do collection { post :sort } resources :children, :controller => :categories, :only => [:index, :new, :create, :new_subcategory] end resources :products do member do put :move_up put :move_down end end resources :faqs do collection { post :sort } end root :to => 'sites#home' match "/savesort" => 'sites#savesort' end match '', to: redirect("/#{I18n.default_locale}") match '*path', to: redirect("/#{I18n.default_locale}/%{path}") But as of right now, it redirects to /en/en/en/en/en/en/en/en/en/en/sites/admin (adds en until browser complains). Any thoughts why it keeps adding /en?

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  • Copying a subset of data to an empty database with the same schema

    - by user193655
    I would like to export part of a database full of data to an empty database. Both databases has the same schema. I want to maintain referential integrity. To simplify my cases it is like this: MainTable has the following fields: 1) MainID integer PK 2) Description varchar(50) 3) ForeignKey integer FK to MainID of SecondaryTable SecondaryTable has the following fields: 4) MainID integer PK (referenced by (3)) 5) AnotherDescription varchar(50) The goal I'm trying to accomplish is "export all records from MainTable using a WHERE condition", for example all records where MainID < 100. To do it manually I shuold first export all data from SecondaryTable contained in this select: select * from SecondaryTable ST outer join PrimaryTable PT on ST.MainID=PT.MainID then export the needed records from MainTable: select * from MainTable where MainID < 100. This is manual, ok. Of course my case is much much much omre complex, I have 200+ tables, so donig it manually is painful/impossible, I have many cascading FKs. Is there a way to force the copy of main table only "enforcing referntial integrity". so that my query is something like: select * from MainTable where MainID < 100 WITH "COPYING ALL FK sources" In this cases also the field (5) will be copied. ====================================================== Is there a syntax or a tool to do this? Table per table I'd like to insert conditions (like MainID <100 is only for MainTable, but I have also other tables).

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  • Method for defining simultaneous has-many and has-one associations between two models in CakePHP?

    - by Hobonium
    One thing with which I have long had problems, within the CakePHP framework, is defining simultaneous hasOne and hasMany relationships between two models. For example: BlogEntry hasMany Comment BlogEntry hasOne MostRecentComment (where MostRecentComment is the Comment with the most recent created field) Defining these relationships in the BlogEntry model properties is problematic. CakePHP's ORM implements a has-one relationship as an INNER JOIN, so as soon as there is more than one Comment, BlogEntry::find('all') calls return multiple results per BlogEntry. I've worked around these situations in the past in a few ways: Using a model callback (or, sometimes, even in the controller or view!), I've simulated a MostRecentComment with: $this->data['MostRecentComment'] = $this->data['Comment'][0]; This gets ugly fast if, say, I need to order the Comments any way other than by Comment.created. It also doesn't Cake's in-built pagination features to sort by MostRecentComment fields (e.g. sort BlogEntry results reverse-chronologically by MostRecentComment.created. Maintaining an additional foreign key, BlogEntry.most_recent_comment_id. This is annoying to maintain, and breaks Cake's ORM: the implication is BlogEntry belongsTo MostRecentComment. It works, but just looks...wrong. These solutions left much to be desired, so I sat down with this problem the other day, and worked on a better solution. I've posted my eventual solution below, but I'd be thrilled (and maybe just a little mortified) to discover there is some mind-blowingly simple solution that has escaped me this whole time. Or any other solution that meets my criteria: it must be able to sort by MostRecentComment fields at the Model::find level (ie. not just a massage of the results); it shouldn't require additional fields in the comments or blog_entries tables; it should respect the 'spirit' of the CakePHP ORM. (I'm also not sure the title of this question is as concise/informative as it could be.)

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  • Should I write more SQL to be more efficient, or less SQL to be less buggy?

    - by RenderIn
    I've been writing a lot of one-off SQL queries to return exactly what a certain page needs and no more. I could reuse existing queries and issue a number of SQL requests linear to the number of records on the page. As an example, I have a query to return People and a query to return Job Details for a person. To return a list of people with their job details I could query once for people and then once for each person to retrieve their job details. I've found that in most cases that solution returns things in a reasonable amount of time, but I don't know how well it will scale in my environment. Instead I've been writing queries to join people + job details, or people + salary history, etc. I'm looking at my models and I see how I could shave off maybe 30% of my code if I were to re-use existing queries. This is a big temptation. Is it a bad thing to go for reuse over efficiency in general or does it all come down to the specific situation? Should I first do it the easy way and then optimize later, or is it best to get the code knocked out while everything is fresh in my mind? Thoughts, experiences?

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  • Executing logic before save or validation with EF Code-First Models

    - by Ryan Norbauer
    I'm still getting accustomed to EF Code First, having spent years working with the Ruby ORM, ActiveRecord. ActiveRecord used to have all sorts of callbacks like before_validation and before_save, where it was possible to modify the object before it would be sent off to the data layer. I am wondering if there is an equivalent technique in EF Code First object modeling. I know how to set object members at the time of instantiation, of course, (to set default values and so forth) but sometimes you need to intervene at different moments in the object lifecycle. To use a slightly contrived example, say I have a join table linking Authors and Plays, represented with a corresponding Authoring object: public class Authoring { public int ID { get; set; } [Required] public int Position { get; set; } [Required] public virtual Play Play { get; set; } [Required] public virtual Author Author { get; set; } } where Position represents a zero-indexed ordering of the Authors associated to a given Play. (You might have a single "South Pacific" Play with two authors: a "Rodgers" author with a Position 0 and a "Hammerstein" author with a Position 1.) Let's say I wanted to create a method that, before saving away an Authoring record, it checked to see if there were any existing authors for the Play to which it was associated. If no, it set the Position to 0. If yes, it would find set the Position of the highest value associated with that Play and increment by one. Where would I implement such logic within an EF code first model layer? And, in other cases, what if I wanted to massage data in code before it is checked for validation errors? Basically, I'm looking for an equivalent to the Rails lifecycle hooks mentioned above, or some way to fake it at least. :)

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  • Add dynamic charts using ASP.NET CHART CONTROL, c#

    - by dhareni
    I wanted to add dynamic charts in the webpage. It goes like this... I get the start and end date from user and draw separate charts for each date bewteen the start and end date. I get the data from sql database and bind it with the chart like this: SqlConnection UsageLogConn = new SqlConnection(ConfigurationManager.ConnectionStrings["UsageConn"].ConnectionString); UsageLogConn.Open();//open connection string sql = "SELECT v.interval,dateadd(mi,(v.interval-1)*2,'" + startdate + " 00:00:00') as 'intervaltime',COUNT(Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2) AS Total FROM usage_internet_intervals v left outer join (select * from Usage_Internet where " + name + " LIKE ('%" + value + "%') and DateTime BETWEEN '" + startdate + " 00:00:00' AND '" + enddate + " 23:59:59') d on v.interval = Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2 GROUP BY v.interval,Datediff(minute,'" + startdate + " 00:00:00',d.DateTime)/2 ORDER BY Interval"; SqlCommand cmd = new SqlCommand(sql, UsageLogConn); SqlDataAdapter mySQLadapter = new SqlDataAdapter(cmd); Chart1.DataSource = cmd; // set series members names for the X and Y values Chart1.Series["Series 1"].XValueMember = "intervaltime"; Chart1.Series["Series 1"].YValueMembers = "Total"; UsageLogConn.Close(); // data bind to the selected data source Chart1.DataBind(); cmd.Dispose(); The above code adds only one chart for one date and I have added 'chart1' to design view and its not created dynamic. But I wanted to add more charts dynamic at runtime to the webpage. Can anyone help me with this? I am using VS 2008, ASP.NET 3.5 and the charting lib is: using System.Web.UI.DataVisualization.Charting;

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  • How to index a table with a Type 2 slowly changing dimension for optimal performance

    - by The Lazy DBA
    Suppose you have a table with a Type 2 slowly-changing dimension. Let's express this table as follows, with the following columns: * [Key] * [Value1] * ... * [ValueN] * [StartDate] * [ExpiryDate] In this example, let's suppose that [StartDate] is effectively the date in which the values for a given [Key] become known to the system. So our primary key would be composed of both [StartDate] and [Key]. When a new set of values arrives for a given [Key], we assign [ExpiryDate] to some pre-defined high surrogate value such as '12/31/9999'. We then set the existing "most recent" records for that [Key] to have an [ExpiryDate] that is equal to the [StartDate] of the new value. A simple update based on a join. So if we always wanted to get the most recent records for a given [Key], we know we could create a clustered index that is: * [ExpiryDate] ASC * [Key] ASC Although the keyspace may be very wide (say, a million keys), we can minimize the number of pages between reads by initially ordering them by [ExpiryDate]. And since we know the most recent record for a given key will always have an [ExpiryDate] of '12/31/9999', we can use that to our advantage. However... what if we want to get a point-in-time snapshot of all [Key]s at a given time? Theoretically, the entirety of the keyspace isn't all being updated at the same time. Therefore for a given point-in-time, the window between [StartDate] and [ExpiryDate] is variable, so ordering by either [StartDate] or [ExpiryDate] would never yield a result in which all the records you're looking for are contiguous. Granted, you can immediately throw out all records in which the [StartDate] is greater than your defined point-in-time. In essence, in a typical RDBMS, what indexing strategy affords the best way to minimize the number of reads to retrieve the values for all keys for a given point-in-time? I realize I can at least maximize IO by partitioning the table by [Key], however this certainly isn't ideal. Alternatively, is there a different type of slowly-changing-dimension that solves this problem in a more performant manner?

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  • c++ queue template

    - by Dalton Conley
    ALright, pardon my messy code please. Below is my queue class. #include <iostream> using namespace std; #ifndef QUEUE #define QUEUE /*---------------------------------------------------------------------------- Student Class # Methods # Student() // default constructor Student(string, int) // constructor display() // out puts a student # Data Members # Name // string name Id // int id ----------------------------------------------------------------------------*/ class Student { public: Student() { } Student(string iname, int iid) { name = iname; id = iid; } void display(ostream &out) const { out << "Student Name: " << name << "\tStudent Id: " << id << "\tAddress: " << this << endl; } private: string name; int id; }; // define a typedef of a pointer to a student. typedef Student * StudentPointer; template <typename T> class Queue { public: /*------------------------------------------------------------------------ Queue Default Constructor Preconditions: none Postconditions: assigns default values for front and back to 0 description: constructs a default empty Queue. ------------------------------------------------------------------------*/ Queue() : myFront(0), myBack(0) {} /*------------------------------------------------------------------------ Copy Constructor Preconditions: requres a reference to a value for which you are copying Postconditions: assigns a copy to the parent Queue. description: Copys a queue and assigns it to the parent Queue. ------------------------------------------------------------------------*/ Queue(const T & q) { myFront = myBack = 0; if(!q.empty()) { // copy the first node myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } /*------------------------------------------------------------------------ Destructor Preconditions: none Postconditions: deallocates the dynamic memory for the Queue description: deletes the memory stored for a Queue. ------------------------------------------------------------------------*/ ~Queue() { NodePointer prev = myFront, ptr; while(prev != NULL) { ptr = prev->next; delete prev; prev = ptr; } } /*------------------------------------------------------------------------ Empty() Preconditions: none Postconditions: returns a boolean value. description: returns true/false based on if the queue is empty or full. ------------------------------------------------------------------------*/ bool empty() const { return (myFront == NULL); } /*------------------------------------------------------------------------ Enqueue Preconditions: requires a constant reference Postconditions: allocates memory and appends a value at the end of a queue description: ------------------------------------------------------------------------*/ void enqueue(const T & value) { NodePointer newNodePtr = new Node(value); if(empty()) { myFront = myBack = newNodePtr; newNodePtr->next = NULL; } else { myBack->next = newNodePtr; myBack = newNodePtr; newNodePtr->next = NULL; } } /*------------------------------------------------------------------------ Display Preconditions: requires a reference of type ostream Postconditions: returns the ostream value (for chaining) description: outputs the contents of a queue. ------------------------------------------------------------------------*/ void display(ostream & out) const { NodePointer ptr; ptr = myFront; while(ptr != NULL) { out << ptr->data << " "; ptr = ptr->next; } out << endl; } /*------------------------------------------------------------------------ Front Preconditions: none Postconditions: returns a value of type T description: returns the first value in the parent Queue. ------------------------------------------------------------------------*/ T front() const { if ( !empty() ) return (myFront->data); else { cerr << "*** Queue is empty -- returning garbage value ***\n"; T * temp = new(T); T garbage = * temp; delete temp; return garbage; } } /*------------------------------------------------------------------------ Dequeue Preconditions: none Postconditions: removes the first value in a queue ------------------------------------------------------------------------*/ void dequeue() { if ( !empty() ) { NodePointer ptr = myFront; myFront = myFront->next; delete ptr; if(myFront == NULL) myBack = NULL; } else { cerr << "*** Queue is empty -- " "can't remove a value ***\n"; exit(1); } } /*------------------------------------------------------------------------ pverloaded = operator Preconditions: requires a constant reference Postconditions: returns a const type T description: this allows assigning of queues to queues ------------------------------------------------------------------------*/ Queue<T> & operator=(const T &q) { // make sure we arent reassigning ourself // e.g. thisQueue = thisQueue. if(this != &q) { this->~Queue(); if(q.empty()) { myFront = myBack = NULL; } else { myFront = myBack = new Node(q.front()); NodePointer qPtr = q.myFront->next; while(qPtr != NULL) { myBack->next = new Node(qPtr->data); myBack = myBack->next; qPtr = qPtr->next; } } } return *this; } private: class Node { public: T data; Node * next; Node(T value, Node * first = 0) : data(value), next(first) {} }; typedef Node * NodePointer; NodePointer myFront, myBack, queueSize; }; /*------------------------------------------------------------------------ join Preconditions: requires 2 queue values Postconditions: appends queue2 to the end of queue1 description: this function joins 2 queues into 1. ------------------------------------------------------------------------*/ template <typename T> Queue<T> join(Queue<T> q1, Queue<T> q2) { Queue<T> q1Copy(q1), q2Copy(q2); Queue<T> jQueue; while(!q1Copy.empty()) { jQueue.enqueue(q1Copy.front()); q1Copy.dequeue(); } while(!q2Copy.empty()) { jQueue.enqueue(q2Copy.front()); q2Copy.dequeue(); } cout << jQueue << endl; return jQueue; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a Queue of type T Postconditions: returns the ostream (for chaining) description: this function is overloaded for outputing a queue with << ----------------------------------------------------------------------------*/ template <typename T> ostream & operator<<(ostream &out, Queue<T> &s) { s.display(out); return out; } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of type Student Postconditions: none description: this function is overloaded for outputing an object of type Student. ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, Student &s) { s.display(out); } /*---------------------------------------------------------------------------- Overloaded << operator Preconditions: requires a constant reference and a reference of a pointer to a Student object. Postconditions: none description: this function is overloaded for outputing pointers to Students ----------------------------------------------------------------------------*/ ostream & operator<<(ostream &out, StudentPointer &s) { s->display(out); } #endif Now I'm having some issues with it. For one, when I add 0 to a queue and then I output the queue like so.. Queue<double> qdub; qdub.enqueue(0); cout << qdub << endl; That works, it will output 0. But for example, if I modify that queue in any way.. like.. assign it to a different queue.. Queue<double> qdub1; Queue<double> qdub2; qdub1.enqueue(0; qdub2 = qdub1; cout << qdub2 << endl; It will give me weird values for 0 like.. 7.86914e-316. Help on this would be much appreciated!

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  • Rails - Scalable calculation model

    - by H O
    I currently have a calculation structure in my rails app that has models metric, operand and operation_type. Presently, the metric model has many operands, and can perform calculations based on the operation_type (e.g. sum, multiply, etc.), and each operand is defined as being right or left (i.e. so that if the operation is division, the numerator and denominator can be identified). Presently, an operand is always an attribute of some model, e.g. @customer.sales.selling_price.sum. In order to make this scalable, in need to allow an operand to be either an attribute of some kind, or the results of a previous operation, i.e. an operand can be a metric. I have included a diagram of how my models currently look: Can anyone assist me with the most elegant way of allowing an operand to be an actual operand, or another metric? Thanks! EDIT: It seems based on the only answer so far that perhaps polymorphic associations are the way to go on this, but the answer is so brief I have no idea how they could be used in this way - can anyone elaborate? EDIT 2: OK, I think I'm getting somewhere - essentially i presently have a metric, which has_many operands, and an operand has_many metrics. I need a polymorphic self join, where a metric can also have many metrics - do I need to call this something else, perhaps calculated_metrics, so that the metric model can use itself? That would leave me with a situation where a metric has_many operands, and a metric has many calculated_metrics.

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