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  • Android: Adding header to dynamic listView

    - by cg5572
    I'm still pretty new to android coding, and trying to figure things out. I'm creating a listview dynamically as shown below (and then disabling items dynamically also) - you'll notice that there's no xml file for the activity itself, just for the listitem. What I'd like to do is add a static header to the page. Could someone explain to me how I can modify the code below to EITHER add this programatically within the java file, before the listView, OR edit the code below so that it targets a listView within an xml file! Help would be much appreciated!!! public class Start extends ListActivity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); DataBaseHelper myDbHelper = new DataBaseHelper(null); myDbHelper = new DataBaseHelper(this); try { myDbHelper.openDataBase(); }catch(SQLException sqle){ throw sqle; } ArrayList<String> categoryList = new ArrayList<String>(); Cursor cur = myDbHelper.getAllCategories(); cur.moveToFirst(); while (cur.isAfterLast() == false) { if (!categoryList.contains(cur.getString(1))) { categoryList.add(cur.getString(1)); } cur.moveToNext(); } cur.close(); Collections.sort(categoryList); setListAdapter(new ArrayAdapter<String>(this, R.layout.listitem, categoryList) { @Override public View getView(int position, View convertView, ViewGroup parent) { View view = super.getView(position, convertView, parent); if(Arrays.asList(checkArray3).contains(String.valueOf(position))){ view.setEnabled(false); } else { view.setEnabled(true); } return view; } }); } @Override protected void onListItemClick(ListView l, View v, int position, long id) { if(v.isEnabled()) { String clickedCat = l.getItemAtPosition(position).toString(); Toast.makeText(this, clickedCat, Toast.LENGTH_SHORT).show(); finish(); Intent myIntent = new Intent(getApplicationContext(), Questions.class); myIntent.putExtra("passedCategory", clickedCat); myIntent.putExtra("startTrigger", "go"); startActivity(myIntent); } } }

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  • mysql get table based on common column between two tables

    - by Zentdayn
    while trying to learn sql i came across "Learn SQL The Hard Way" and i started reading it. Everything was going fine then i thought ,as a way to practice, to make something like given example in the book (example consists in 3 tables pet,person,person_pet and the person_pet table 'links' pets to their owners). I made this: report table +----+-------------+ | id | content | +----+-------------+ | 1 | bank robbery| | 2 | invalid | | 3 | cat on tree | +----+-------------+ notes table +-----------+--------------------+ | report_id | content | +-----------+--------------------+ | 1 | they had guns | | 3 | cat was saved | +-----------+--------------------+ wanted result +-----------+--------------------+---------------+ | report_id | report_content | report_notes | +-----------+--------------------+---------------+ | 1 | bank robbery | they had guns | | 2 | invalid | null or '' | | 3 | cat on tree | cat was saved | +-----------+--------------------+---------------+ I tried a few combinations but no success. My first thought was SELECT report.id,report.content AS report_content,note.content AS note_content FROM report,note WHERE report.id = note.report_id but this only returns the ones that have a match (would not return the invalid report). after this i tried adding IF conditions but i just made it worse. My question is, is this something i will figure out after getting past basic sql or can this be done in simple way? Anyway i would appreciate any help, i pretty much lost with this. Thank you. EDIT: i have looked into related questions but havent yet found one that solves my problem. I probably need to look into other statements such as join or something to sort this out.

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  • How to maintain ComboBox.SelectedItem reference when DataSource is resorted?

    - by Dave
    This really seems like a bug to me, but perhaps some databinding gurus can enlighten me? (My WinForms databinding knowledge is quite limited.) I have a ComboBox bound to a sorted DataView. When the properties of the items in the DataView change such that items are resorted, the SelectedItem in my ComboBox does not keep in-sync. It seems to point to someplace completely random. Is this a bug, or am I missing something in my databinding? Here is a sample application that reproduces the problem. All you need is a Button and a ComboBox: public partial class Form1 : Form { private DataTable myData; public Form1() { this.InitializeComponent(); this.myData = new DataTable(); this.myData.Columns.Add("ID", typeof(int)); this.myData.Columns.Add("Name", typeof(string)); this.myData.Columns.Add("LastModified", typeof(DateTime)); this.myData.Rows.Add(1, "first", DateTime.Now.AddMinutes(-2)); this.myData.Rows.Add(2, "second", DateTime.Now.AddMinutes(-1)); this.myData.Rows.Add(3, "third", DateTime.Now); this.myData.DefaultView.Sort = "LastModified DESC"; this.comboBox1.DataSource = this.myData.DefaultView; this.comboBox1.ValueMember = "ID"; this.comboBox1.DisplayMember = "Name"; } private void saveStuffButton_Click(object sender, EventArgs e) { DataRowView preUpdateSelectedItem = (DataRowView)this.comboBox1.SelectedItem; // OUTPUT: SelectedIndex = 0; SelectedItem.Name = third Debug.WriteLine(string.Format("SelectedIndex = {0:N0}; SelectedItem.Name = {1}", this.comboBox1.SelectedIndex, preUpdateSelectedItem["Name"])); this.myData.Rows[0]["LastModified"] = DateTime.Now; DataRowView postUpdateSelectedItem = (DataRowView)this.comboBox1.SelectedItem; // OUTPUT: SelectedIndex = 2; SelectedItem.Name = second Debug.WriteLine(string.Format("SelectedIndex = {0:N0}; SelectedItem.Name = {1}", this.comboBox1.SelectedIndex, postUpdateSelectedItem["Name"])); // FAIL! Debug.Assert(object.ReferenceEquals(preUpdateSelectedItem, postUpdateSelectedItem)); } }

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  • How to maintain a persistant network-connection between two applications over a network?

    - by John
    I was recently approached by my management with an interesting problem - where I am pretty sure I am telling my bosses the correct information but I really want to make sure I am telling them the correct stuff. I am being asked to develop some software that has this function: An application at one location is constantly processing real-time data every second and only generates data if the underlying data has changed in any way. On the event that the data has changed send the results to another box over a network Maintains a persistent connection between the both machines, altering the remote box if for some reason the network connection went down From what I understand, I imagine that I need to do some reading on doing some sort of TCP/IP socket-level stuff. That way if the connection is dropped the remote location will be aware that the data it has received may be stale. However management seems to be very convinced that this can be accomplished using SOAP. I was under the impression that SOAP is more or less a way for a client to initiate a procedure from a server and get some results via the HTTP protocol. Am I wrong in assuming this? I haven't been able to find much information on how SOAP might be able to solve a problem like this. I feel like a lot of people around my office are using SOAP as a buzzword and that has generated a bit of confusion over what SOAP actually is - and is capable of. Any thoughts on how to accomplish this task would be appreciated!

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  • Anyone NOT using a Web Framework? Why?

    - by tom
    I'm well aware of the many reasons to use a web framework. I'm just wondering whether anyone out there is using absolutely no web framework whatsoever to develop their web projects. I would really love to know the reason(s) why you're not using a web framework. For the sake of this discussion, your programming language of choice does not matter. Some possibilities for discussion: You don't hide behind an ORM. You don't rely on any sort of templating system. You think MVC is a really nice TLA but lacks an essential vowel or two. No need for any additional javascript framework tomfoolery. You just write as much code as possible in your native programming language(s). Summary of reasons thus far: Language learning opportunities. Specific performance reasons (write-intensive transaction processing). Seeking more nuanced control over your data and applications (less abstraction). You're building your own framework! Prove to yourself that you can succeed (or fail) just like the big framework-building gurus. Integration issues with unpopular/legacy technologies (exotic databases or protocols come to mind). Big company, lots of code, no talent nor buy-in present to move to a web framework. Some frameworks really lock you in and cannot perpetually grow along with your needs. These few black sheep don't make it easy to jump outside of the framework, write some custom code, and easily jump back in. When you finally escape the asylum, you'll never look back.

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  • How can I lookup data about a book from its barcode number?

    - by Joel Spolsky
    I'm building the world's simplest library application. All I want to be able to do is scan in a book's UPC (barcode) using a typical scanner (which just types the numbers of the barcode into a field) and then use it to look up data about the book... at a minimum, title, author, year published, and either the Dewey Decimal or Library of Congress catalog number. The goal is to print out a tiny sticker ("spine label") with the card catalog number that I can stick on the spine of the book, and then I can sort the books by card catalog number on the shelves in our company library. That way books on similar subjects will tend to be near each other, for example, if you know you're looking for a book about accounting, all you have to do is find SOME book about accounting and you'll see the other half dozen that we have right next to it which makes it convenient to browse the library. There seem to be lots of web APIs to do this, including Amazon and the Library of Congress. But those are all extremely confusing to me. What I really just want is a single higher level function that takes a UPC barcode number and returns some basic data about the book.

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  • Most efficient way to LIMIT results in a JOIN?

    - by johnnietheblack
    I have a fairly simple one-to-many type join in a MySQL query. In this case, I'd like to LIMIT my results by the left table. For example, let's say I have an accounts table and a comments table, and I'd like to pull 100 rows from accounts and all the associated comments rows for each. Thy only way I can think to do this is with a sub-select in in the FROM clause instead of simply selecting FROM accounts. Here is my current idea: SELECT a.*, c.* FROM (SELECT * FROM accounts LIMIT 100) a LEFT JOIN `comments` c on c.account_id = a.id ORDER BY a.id However, whenever I need to do a sub-select of some sort, my intermediate level SQL knowledge feels like it's doing something wrong. Is there a more efficient, or faster, way to do this, or is this pretty good? By the way... This might be the absolute simplest way to do this, which I'm okay with as an answer. I'm simply trying to figure out if there IS another way to do this that could potentially compete with the above statement in terms of speed.

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  • Django filters - Using an AllValuesFilter (with a LinkWidget) on a ManyToManyField

    - by magnetix
    This is my first Stack Overflow question, so please let me know if I do anything wrong. I wish to create an AllValues filter on a ManyToMany field using the wonderful django-filters application. Basically, I want to create a filter that looks like it does in the Admin, so I also want to use the LinkWidget too. Unfortunately, I get an error (Invalid field name: 'operator') if I try this the standard way: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class SignFilter(LinkOrderFilterSet): operator = django_filters.AllValuesFilter(widget=django_filters.widgets.LinkWidget) class Meta: model = Sign fields = ['operator'] I got around this by creating my own filter with the many to many relationship hard coded: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class MyFilter(django_filters.ChoiceFilter): @property def field(self): cd = {} for row in self.model.objects.all(): orgs = row.operator.select_related().values() for org in orgs: cd[org['id']] = org['name'] choices = zip(cd.keys(), cd.values()) list.sort(choices, key=lambda x:(x[1], x[0])) self.extra['choices'] = choices return super(AllValuesFilter, self).field class SignFilter(LinkOrderFilterSet): operator = MyFilter(widget=django_filters.widgets.LinkWidget) I am new to Python and Django. Can someone think of a more generic/elegant way of doing this?

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  • What's the most efficient way to load data from a file to a collection on-demand?

    - by Dan
    I'm working on a java project that will allows users to parse multiple files with potentially thousands of lines. The information parsed will be stored in different objects, which then will be added to a collection. Since the GUI won't require to load ALL these objects at once and keep them in memory, I'm looking for an efficient way to load/unload data from files, so that data is only loaded into the collection when a user requests it. I'm just evaluation options right now. I've also thought of the case where, after loading a subset of the data into the collection, and presenting it on the GUI, the best way to reload the previously observed data. Re-run the parser/Populate collection/Populate GUI? or probably find a way to keep the collection into memory, or serialize/deserialize the collection itself? I know that loading/unloading subsets of data can get tricky if some sort of data filtering is performed. Let's say that I filter on ID, so my new subset will contain data from two previous analyzed subsets. This would be no problem is I keep a master copy of the whole data in memory. I've read that google-collections are good and efficient when handling big amounts of data, and offer methods that simplify lots of things so this might offer an alternative to allow me to keep the collection in memory. This is just general talking. The question on what collection to use is a separate and complex thing. Do you know what's the general recommendation on this type of task? I'd like to hear what you've done with similar scenarios. I can provide more specifics if needed.

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  • Best solution for an StringToInt function in C#

    - by StefanE
    Hi, I were asked to do an StringToInt / Int.parse function on the white board in an job interview last week and did not perform very good but I came up with some sort of solution. Later when back home I made one in Visual Studion and I wonder if there are any better solution than mine below. Have not bothred with any more error handling except checking that the string only contains digits. private int StrToInt(string tmpString) { int tmpResult = 0; System.Text.Encoding ascii = System.Text.Encoding.ASCII; byte[] tmpByte = ascii.GetBytes(tmpString); for (int i = 0; i <= tmpString.Length-1; i++) { // Check whatever the Character is an valid digit if (tmpByte[i] > 47 && tmpByte[i] <= 58) // Here I'm using the lenght-1 of the string to set the power and multiply this to the value tmpResult += (tmpByte[i] - 48) * ((int)Math.Pow(10, (tmpString.Length-i)-1)); else throw new Exception("Non valid character in string"); } return tmpResult; }

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  • Why is Func<T> ambiguous with Func<IEnumerable<T>>?

    - by Matt Hamilton
    This one's got me flummoxed, so I thought I'd ask here in the hope that a C# guru can explain it to me. Why does this code generate an error? class Program { static void Main(string[] args) { Foo(X); // the error is on this line } static String X() { return "Test"; } static void Foo(Func<IEnumerable<String>> x) { } static void Foo(Func<String> x) { } } The error in question: Error 1 The call is ambiguous between the following methods or properties: 'ConsoleApplication1.Program.Foo(System.Func<System.Collections.Generic.IEnumerable<string>>)' and 'ConsoleApplication1.Program.Foo(System.Func<string>)' C:\Users\mabster\AppData\Local\Temporary Projects\ConsoleApplication1\Program.cs 12 13 ConsoleApplication1 It doesn't matter what type I use - if you replace the "String" declarations with "int" in that code you'll get the same sort of error. It's like the compiler can't tell the difference between Func<T> and Func<IEnumerable<T>>. Can someone shed some light on this?

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  • Tracking down slow managed DLL loading

    - by Alex K
    I am faced with the following issue and at this point I feel like I'm severely lacking some sort of tool, I just don't know what that tool is, or what exactly it should be doing. Here is the setup: I have a 3rd party DLL that has to be registered in GAC. This all works fine and good on pretty much every machine our software was deployed on before. But now we got 2 machines, seemingly identical to the ones we know work (they are cloned from the same image and stuffed with the same hardware, so pretty much the only difference is software settings, over which I went over and over, and they seem fine). Now the problem, the DLL in GAC takes a very long time to load. At least I believe this is the issue, what I can say definitively is that instantiating a single class from that DLL is the slow part. Once it is loaded, thing fly as they always have. But while on known-good machines the DLL loads so fast that a timestamp in the log doesn't even change, on these 2 machines it take over 1min to load. Knowns: I have no access to the source, so I can't debug through the DLL. Our app is the only one that uses it (so shouldn't be simultaneous access issues). There is only one version of this DLL in existance, so it shouldn't be a matter of version conflict. The GAC reference is being used (if I uninstall the DLL from GAC, an exception will be thrown about the missing GAC reference). Could someone with a greater skill in debug-fu suggest what I can do to track down the root cause of this issue?

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  • Qt moc not error

    - by Robert Parker
    So I'm pretty new to Qt, and I've just inherited a project from someone else who is also new to Qt. He isn't around this week btw. We are using Visual Studio 2008, and have the latest version of Qt installed(4.6.2). The project builds on my coworker's machine fine, and I can get the project from svn and build it directly. But under any other circumstances it refuses to build on my machine, and it doesn't give me much of an explanation why. Even if I just do a 'build clean' and then a 'build' it doesn't work. Any slight modification will make it fail. When I try to build the entire project I get the error message: 1Moc'ing MatrixTypeInterface.h... 1moc: Cannot create .\GeneratedFiles\Debug\moc_MatrixTypeInterface.cpp;.\GeneratedFiles\Debug\moc_matrixtypeinterface.cpp 1Project : error PRJ0019: A tool returned an error code from "Moc'ing MatrixTypeInterface.h..." The moc tool doesn't give any sort of error message as to why it isn't working, and I wasted most of yesterday trying to figure out why. I got the command that VS was using to call moc, and I entered in the command line myself. It didn't write anything to the screen. Any ideas?

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  • Git repos over multiple machines - backups and keeping in sync

    - by a-or-b
    I'm new to git so please feel free to RTFM me... I have multiple development sites (none of which can communicate via a network with each other) and am working on a few projects (with a few people) at any one time. What I would ideally have is at each site a centralized repository that can be pulled from but development would occur in our own (personal) repos. Then I would like to be able to sync across the centralized repos (via USB key for example). I want a centralized repo at each location as (1) I'm new to git and do break my (personal) local repo by playing around and (2) some projects get put on hold so I want to be able to free up disk space by deleting them. This is the "backup" part of my question. I was also hoping to be able to use 'git clone --bare' for my centralized repos (and the USB key repos to?) as we don't need the full checkout, just the git benefits. However I can't seem to get a bare repo to work as repo I can push from. I've used 'git remote' to set up an remote origin (similar to http://toolmantim.com/thoughts/setting_up_a_new_remote_git_repository) but I can't get 'git push' to work - it seems I need a checked-out repo. . Does anyone else use this sort of repo/development structure or is there something fundamental about git usage that I'm missing? . A solution that I thought about that might not work - If I had a 'git clone --bare' at each site and then use a git repo on my removable media which has remotes set up for each site then I could ('pull') sync my USB key with each repo. But then can I update the site repo from my USB key? Could I push from USB?

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  • Unable to access SQL reporting services on shared site with Themes enabled

    - by Grant
    Hi, i am having some trouble with my IIS web server & SQL reporting services. At the current time my site is playing host to both reporting services (/reports & /reportserver) as well as my personal website (domain.com) Only just recently have i implemented a Theme on my site and as such i have placed a statement in my web.config file directing it to apply a certain theme in the following manner <pages styleSheetTheme="General"> Because of this when i try to access the report pages it failed telling me it couldnt find the Theme so what i did was locate the source files for the /reports & /reportserver directories and place the App_Theme folder in them hoping that would sort everything out. What i am getting now is the following error *Using themed css files requires a header control on the page. e.g. head runat="server" * Does anyone know how i can get around this? Do i have to hack the sql reporting aspx pages? Please note i do NOT want to remove the web.config declaration.

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  • Saving a single entity instead of the entire context - revisited

    - by nite
    I’m looking for a way to have fine grained control over what is saved using Entity Framework, rather than the whole ObjectContext.SaveChanges(). My scenario is pretty straight forward, and I’m quite amazed not catered for in EF – pretty basic in NHibernate and all other data access paradigms I’ve seen. I’m generating a bunch of data (in a WPF UI) and allowing the user to fine tune what is proposed and choose what is actually committed to the database. For the proposed entities I’m: getting a bunch of reference entities (eg languages) via my objectcontext, creating the proposed entities and assigning these reference entities to them (as navigation properties), so by virtue of their relationship to the reference entities they’re implicitly added to the objectconext Trying to create & save individual entites based on the proposed entities. I figure this should be really simple & trivial but everything I’ve tried I’ve hit a brick wall, either I set up another objectcontext & add just the entity I need (it then tries to add the whole graph and fails as it’s on another objectcontext). I’ve tried MergeOptions = NoTracking on my reference entities to try to get the Attach/AddObject not to navigate through these to create a graph, no avail. I've removed the navigation properties from the reference entities. I've tried AcceptAllChanges, that works but pretty useless in practice as I do still want to track & save other entities. In a simple test, I can create 2 of my proposed entities, AddObject the one I want to save and then Detach the one I dont then call SaveChanges, this works but again not great in practice. Following are a few links to some of the nifty ideas which in the end don’t help in the end but illustrate the complexity of EF for something so simple. I’m really looking for a SaveSingle/SaveAtomic method, and think it’s a pretty reasonable & basic ask for any DAL, letalone a cutting edge ORM. http://stackoverflow.com/questions/1301460/saving-a-single-entity-instead-of-the-entire-context www.codeproject.com/KB/architecture/attachobjectgraph.aspx?fid=1534536&df=90&mpp=25&noise=3&sort=Position&view=Quick&select=3071122&fr=1 bernhardelbl.spaces.live.com/blog/cns!DB54AE2C5D84DB78!238.entry

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  • Approaches for animating a C# property over time?

    - by Mario Fritsch
    I'm currently trying to animate a bunch of public properties on certain objects. Usually they are of type float or vectors of floats (the type is known at compile-time). I want to be able to: assign a static value to them (MyObject.Duration = 10f;) or assign a random value to them by specifying a minimum and maximum value and optionally also a weight (MyObject.Duration = new RandomFloat(5f, 20f, 2f);) or "bind" this property to the property of another object (think of a child object binding some of its properties to its parent object, like its color or size or sth.) or assign sort of a keyframe animation to them, specifying a variable number of keyframes with timecode and the property's value at that specific point in time as well as information about how to interpolate between these frames The keyframes should be able to accept random values for each frame, both for the time and the property's value. What would be a practical approach for this kind of system? Currently I'm thinking about polymorphism: implement a base class or interface with a public Value-property and/or GetValue(float time)-method and then creating different sub classes like StaticValue, RandomValue, BindingValue and AnimatedValue implementing this base class or interface. Doesn't seem very elegant, though, and the initialization of even simple objects becomes a bit tedious. Another idea would be to implement these properties just as regular floats or vectors and create special "Modifier"-types binding to these properties. To retrieve the "real" value of the property, I'd first call any Modifier bound to the property, which would in turn update the actual object's property for me to retrieve later on. That would most likely mean using reflection at some point, which could be quite bad for performance as I'll probably have thousands of properties to update dozens of times per second. Any suggestions on this? Being a novice I'm (hopefully) missing some far more elegant and/or practical solution than I'm already playing around with :( Edit: Probably should have mentioned this earlier, but WPF isn't an option - it's not available on all targetted platforms, so I can't rely on it. I'm aware of its powerful databinding and animation capabilities, but I need to roll my own (or find some other lightweight alternative meeting my needs).

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  • Need some clarification on the ANSI/SPARC 3-tier database architecture.

    - by Moonshield
    Hi there, I'm currently revising for a databases exam and looking over some past papers, but there's one question that I'm slightly unsure about and was wondering if someone could offer some assistance. "Describe EACH of the THREE levels of the ANSI SPARC 3 level architecture. Your answer should include the purpose of EACH of the schemas, the level of abstraction they provide and the software tools that would be used to access and support them." As I understand it (although please correct me if I'm wrong): the internal schema specifies the physical storage of the data; the conceptual schema specifies the structure of the database and the domains; and the external schemas are how the database is viewed by "users" (applications, etc.). As for the abstraction, I understand that the conceptual layer means that the physical data storage can be altered without the end user being affected, likewise the The bit that I'm not sure about is what tools are used to access and support each layer. Would the internal schema be handled by the DBMS, the conceptual schema handled by some sort of DDL interpreter and the external schema handled by a DML interpreter (or have I misunderstood what each level does)? Any assistance would be greatly appreciated. Thanks, Moonshield

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  • Bind an Incode DataTemplate in WPF

    - by Mike Bynum
    I have a WPF Application which is using MVVM. I know that there ways of doing this in XAML but I am working on a plugin architecture and came up with a solution where a plugin exposes it's viewmodel to my plugin host's viewmodel and it's datatemplate. I want to leave the lifetime management of the plugin view up to WPF. I have tried having the plugins expose a UserControl but ran into issues when WPF decided to dispose of my UserControl so I would not reattach it without weird hacky work arounds. I am having issues getting some sort of binding working to where i can bind a control to the data and it's template to my data template. I have a ViewModel which looks something like: public class MyViewModel { public DataTemplate SelectedTemplate{ get; set;} public object SelectedViewModel {get; set;} } The selected template and viewmodel are determined somewhere else in the code but are irrelevant to my question. My question is how i can bind to a DataTemplate so that I know how to display the data shown in the SelectedViewModel. The DataTemplate is a DataTemplate created incode which respresents: <DataTemplate DataType="{x:Type vm:MyViewModel}"> <v:MyUserControl /> </DataTemplate> I have tried: <UserControl Template="{Binding Path=SelectedTemplate}" Content="{Binding Path=SelectedViewModel"} /> But UserControl expects a control template and not a data template.

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  • Java/Hibernate using interfaces over the entities.

    - by Dennetik
    I am using annoted Hibernate, and I'm wondering whether the following is possible. I have to set up a series of interfaces representing the objects that can be persisted, and an interface for the main database class containing several operations for persisting these objects (... an API for the database). Below that, I have to implement these interfaces, and persist them with Hibernate. So I'll have, for example: public interface Data { public String getSomeString(); public void setSomeString(String someString); } @Entity public class HbnData implements Data, Serializable { @Column(name = "some_string") private String someString; public String getSomeString() { return this.someString; } public void setSomeString(String someString) { this.someString = someString; } } Now, this works fine, sort of. The trouble comes when I want nested entities. The interface of what I'd want is easy enough: public interface HasData { public Data getSomeData(); public void setSomeData(Data someData); } But when I implement the class, I can follow the interface, as below, and get an error from Hibernate saying it doesn't know the class "Data". @Entity public class HbnHasData implements HasData, Serializable { @OneToOne(cascade = CascadeType.ALL) private Data someData; public Data getSomeData() { return this.someData; } public void setSomeData(Data someData) { this.someData = someData; } } The simple change would be to change the type from "Data" to "HbnData", but that would obviously break the interface implementation, and thus make the abstraction impossible. Can anyone explain to me how to implement this in a way that it will work with Hibernate?

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  • What's the best way to "shuffle" a table of database records?

    - by Darth
    Say that I have a table with a bunch of records, which I want to randomly present to users. I also want users to be able to paginate back and forth, so I have to perserve some sort of order, at least for a while. The application is basically only AJAX and it uses cache for already visited pages, so even if I always served random results, when the user tries to go back, he will get the previous page, because it will load from the local cache. The problem is, that if I return only random results, there might be some duplicates. Each page contains 6 results, so to prevent this, I'd have to do something like WHERE id NOT IN (1,2,3,4 ...) where I'd put all the previously loaded IDs. Huge downside of that solution is that it won't be possible to cache anything on the server side, as every user will request different data. Alternate solution might be to create another column for ordering the records, and shuffle it every insert time unit here. The problem here is, I'd need to set random number out of a sequence to every record in the table, which would take as many queries as there are records. I'm using Rails and MySQL if that's of any relevance.

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  • Managing libraries and imports in a programming language

    - by sub
    I've created an interpreter for a stupid programming language in C++ and the whole core structure is finished (Tokenizer, Parser, Interpreter including Symbol tables, core functions, etc.). Now I have a problem with creating and managing the function libraries for this interpreter (I'll explain what I mean with that later) So currently my core function handler is horrible: // Simplified version myLangResult SystemFunction( name, argc, argv ) { if ( name == "print" ) { if( argc < 1 ) { Error('blah'); } cout << argv[ 0 ]; } else if ( name == "input" ) { if( argc < 1 ) { Error('blah'); } string res; getline( cin, res ); SetVariable( argv[ 0 ], res ); } else if ( name == "exit ) { exit( 0 ); } And now think of each else if being 10 times more complicated and there being 25 more system functions. Unmaintainable, feels horrible, is horrible. So I thought: How to create some sort of libraries that contain all the functions and if they are imported initialize themselves and add their functions to the symbol table of the running interpreter. However this is the point where I don't really know how to go on. What I wanted to achieve is that there is e.g.: an (extern?) string library for my language, e.g.: string, and it is imported from within a program in that language, example: import string myString = "abcde" print string.at( myString, 2 ) # output: c My problems: How to separate the function libs from the core interpreter and load them? How to get all their functions into a list and add it to the symbol table when needed? What I was thinking to do: At the start of the interpreter, as all libraries are compiled with it, every single function calls something like RegisterFunction( string namespace, myLangResult (*functionPtr) ); which adds itself to a list. When import X is then called from within the language, the list built with RegisterFunction is then added to the symbol table. Disadvantages that spring to mind: All libraries are directly in the interpreter core, size grows and it will definitely slow it down.

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  • PHP - dynamic page via subdomain

    - by Phil Jackson
    Hi, im creating profile pages based on a subdomains using the wildcard DNS setting. Problem being, if the subdomain is incorrect, I want it to redirect to the same page but without the subdomain infront ie; if ( preg_match('/^(www\.)?([^.]+)\.domainname\.co.uk$/', $_SERVER['HTTP_HOST'], $match)) { $DISPLAY_NAME = $match[2]; $query = "SELECT * FROM `" . ACCOUNT_TABLE . "` WHERE DISPLAY_NAME = '$DISPLAY_NAME' AND ACCOUNT_TYPE = 'premium_account'"; $q = mysql_query( $query, $CON ) or die( "_error_" . mysql_error() ); if( mysql_num_rows( $q ) != 0 ) { }else{ mysql_close( $CON ); header("location: http://www.domainname.co.uk"); exit; } } I get a browser error: Firefox has detected that the server is redirecting the request for this address in a way that will never complete. I think its because when using header("location: http://www.domainname.co.uk"); it still puts the sub domain infront i.e. ; header("location: http://www.sub.domainname.co.uk"); Does anyone know how to sort this and/or what is the problem. Regards, Phil

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  • PHP Outputting File Attachments with Headers

    - by OneNerd
    After reading a few posts here I formulated this function which is sort of a mishmash of a bunch of others: function outputFile( $filePath, $fileName, $mimeType = '' ) { // Setup $mimeTypes = array( 'pdf' => 'application/pdf', 'txt' => 'text/plain', 'html' => 'text/html', 'exe' => 'application/octet-stream', 'zip' => 'application/zip', 'doc' => 'application/msword', 'xls' => 'application/vnd.ms-excel', 'ppt' => 'application/vnd.ms-powerpoint', 'gif' => 'image/gif', 'png' => 'image/png', 'jpeg' => 'image/jpg', 'jpg' => 'image/jpg', 'php' => 'text/plain' ); // Send Headers //-- next line fixed as per suggestion -- header('Content-Type: ' . $mimeTypes[$mimeType]); header('Content-Disposition: attachment; filename="' . $fileName . '"'); header('Content-Transfer-Encoding: binary'); header('Accept-Ranges: bytes'); header('Cache-Control: private'); header('Pragma: private'); header('Expires: Mon, 26 Jul 1997 05:00:00 GMT'); readfile($filePath); } I have a php page (file.php) which does something like this (lots of other code stripped out): // I run this thru a safe function not shown here $safe_filename = $_GET['filename']; outputFile ( "/the/file/path/{$safe_filename}", $safe_filename, substr($safe_filename, -3) ); Seems like it should work, and it almost does, but I am having the following issues: When its a text file, I am getting a strange symbol as the first letter in the text document When its a word doc, it is corrupt (presumably that same first bit or byte throwing things off). I presume all other file types will be corrupt - have not even tried them Any ideas on what I am doing wrong? Thanks - UPDATE: changed line of code as suggested - still same issue.

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  • Can C++ do something like an ML case expression?

    - by Nathan Andrew Mullenax
    So, I've run into this sort of thing a few times in C++ where I'd really like to write something like case (a,b,c,d) of (true, true, _, _ ) => expr | (false, true, _, false) => expr | ... But in C++, I invariably end up with something like this: bool c11 = color1.count(e.first)>0; bool c21 = color2.count(e.first)>0; bool c12 = color1.count(e.second)>0; bool c22 = color2.count(e.second)>0; // no vertex in this edge is colored // requeue if( !(c11||c21||c12||c22) ) { edges.push(e); } // endpoints already same color // failure condition else if( (c11&&c12)||(c21&&c22) ) { results.push_back("NOT BICOLORABLE."); return true; } // nothing to do: nodes are already // colored and different from one another else if( (c11&&c22)||(c21&&c12) ) { } // first is c1, second is not set else if( c11 && !(c12||c22) ) { color2.insert( e.second ); } // first is c2, second is not set else if( c21 && !(c12||c22) ) { color1.insert( e.second ); } // first is not set, second is c1 else if( !(c11||c21) && c12 ) { color2.insert( e.first ); } // first is not set, second is c2 else if( !(c11||c21) && c22 ) { color1.insert( e.first ); } else { std::cout << "Something went wrong.\n"; } I'm wondering if there's any way to clean all of those if's and else's up, as it seems especially error prone. It would be even better if it were possible to get the compiler complain like SML does when a case expression (or statement in C++) isn't exhaustive. I realize this question is a bit vague. Maybe, in sum, how would one represent an exhaustive truth table with an arbitrary number of variables in C++ succinctly? Thanks in advance.

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