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• Pro ASP.Net MVC 3 Entity Framework Sports Store tutorial

  - by gary7

  Following the tutorial in the book "Pro ASP.Net MVC 3 Entity Framework" in Chapter 9 - Image Uploads section; asks that the Product class be updated with two new columns - public byte ImageData, and public string ImageType. It also directs that the database be updated with these two columns via the server explorer. After these updates, the discussion directs that the Entity Framework Conceptual Model be updated via the SportsStore.EDMX file. This file does not exist in the source code for the project, and was not used in the project to begin with. Obvious errata for the book. Adding the ADO.NET Entity Data Model to the Project then overrides the EFProduct reposistory (conceptual model used throughout the project) which inherits from the interface IProductsRepository; and results in errors within the mapping. If the project is debugged after the columns are added, an error is thrown related to the new added columns. Has anyone resolved this issue in the project? I haven't found any solutions so far. Thanks!

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• Get Image from Byte Aarray.

  - by Arun Thakkar

  Hello Everyone!! Hope You all are fine and also in one of your best of moods!! Hope You all are Enjoying iPhone development. I herewith one issue that i am not able to solve, may be i don't know the depth concept of iPhone. So Its my humble requet to you to guide me or suggest or share your ideas. I do find an issue with getting an image from Bytes array. I am calling a webservice which returns an image in form of Bytes Array as response. I have Converted this bytes array in to form of NSData, Now i have NSData, But When i Try to get an image from this NSData, It shows nil. I Did lots of R&D and Find one suggestion to use base64 encoder, But unfortunately because of not proper guidance I was not able to Implement that. I was also suggested to use OPenSSL Library for base64 from url http://www.cocoadev.com/index.pl?BaseSixtyFour But again i was not able to include #include #include these two files. as in Newer Version of SDK 3.X family Apple has depreciated those (as i guess). So Now i need help from you guys. kindly help me if you have solution or if you know the steps to solve these. Looking Forwards. Regards, Arun Thakkar

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• What is best practice about having one-many hibernate

  - by Patrick

  Hi all, I believe this is a common scenario. Say I have a one-many mapping in hibernate Category has many Item Category: @OneToMany( cascade = {CascadeType.ALL},fetch = FetchType.LAZY) @JoinColumn(name="category_id") @Cascade( value = org.hibernate.annotations.CascadeType.DELETE_ORPHAN ) private List<Item> items; Item: @ManyToOne(targetEntity=Category.class,fetch=FetchType.EAGER) @JoinColumn(name="category_id",insertable=false,updatable=false) private Category category; All works fine. I use Category to fully control Item's life cycle. But, when I am writing code to update Category, first I get Category out from DB. Then pass it to UI. User fill in altered values for Category and pass back. Here comes the problem. Because I only pass around Category information not Item. Therefore the Item collection will be empty. When I call saveOrUpdate, it will clean out all associations. Any suggestion on what's best to address this? I think the advantage of having Category controls Item is to easily main the order of Item and not to confuse bi-directly. But what about situation that you do want to just update Category it self? Load it first and merge? Thank you.

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• How to get to the key name of a referenced entity property from an entity instance without a datastore read in google app engine?

  - by Sumeet Pareek

  Consider I have the following models - class Team(db.Model): # say I have just 5 teams name = db.StringProperty() class Player(db.Model): # say I have thousands of players name = db.StringProperty() team = db.ReferenceProperty(Team, collection_name="player_set") Key name for each Team entity = 'team_' , and for each Player entity = 'player_' By some prior arrangement I have a Team entity's (key_name, name) mapping available to me. For example (team_01, United States Of America), (team_02, Russia) etc I have to show all the players and their teams on a page. One way of doing this would be - players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(player.team.name) #This is a total of 1x1000 = 1000 DB reads That is a 1001 DB reads for a silly thing. The interesting part is that when I do a db.to_dict() on players, it shows that for every player in that list there is 'name' of the player and there is the 'key_name' of the team available too. So how can I do the below ?? players = Player.all().fetch(1000) # This is 1 DB read for player in players: # This will iterate 1000 times self.response.out.write(player.name) # This is obviously not a DB read self.response.out.write(team_list[player.<SOME WAY OF GETTING TEAM KEY NAME>]) # Here 'team_list' already has (key_name, name) for all 5 teams I have been struggling with this for a long time. Have read every available documentation. I could just hug the person that can help me here :-) Disclaimer: The above problem description is not a real scenario. It is a simplified arrangement that represents my problem exactly. I have run into it in a rater complex and big GAE appication.

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• Referencing not-yet-defined variables - Java

  - by user2537337

  Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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• Serializing Configurations for a Dependency Injection / Inversion of Control

  - by Joshua Starner

  I've been researching Dependency Injection and Inversion of Control practices lately in an effort to improve the architecture of our application framework and I can't seem to find a good answer to this question. It's very likely that I have my terminology confused, mixed up, or that I'm just naive to the concept right now, so any links or clarification would be appreciated. Many examples of DI and IoC containers don't illustrate how the container will connect things together when you have a "library" of possible "plugins", or how to "serialize" a given configuration. (From what I've read about MEF, having multiple declarations of [Export] for the same type will not work if your object only requires 1 [Import]). Maybe that's a different pattern or I'm blinded by my current way of thinking. Here's some code for an example reference: public abstract class Engine { } public class FastEngine : Engine { } public class MediumEngine : Engine { } public class SlowEngine : Engine { } public class Car { public Car(Engine e) { engine = e; } private Engine engine; } This post talks about "Fine-grained context" where 2 instances of the same object need different implementations of the "Engine" class: http://stackoverflow.com/questions/2176833/ioc-resolve-vs-constructor-injection Is there a good framework that helps you configure or serialize a configuration to achieve something like this without hard coding it or hand-rolling the code to do this? public class Application { public void Go() { Car c1 = new Car(new FastEngine()); Car c2 = new Car(new SlowEngine()); } } Sample XML: <XML> <Cars> <Car name="c1" engine="FastEngine" /> <Car name="c2" engine="SlowEngine" /> </Cars> </XML>

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• C++ Declarative Parsing Serialization

  - by Martin York

  Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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• Configuring PHP in IIS with Tomcat

  - by Silent Walker

  I have my Java site running under IIS 7. I need to install wordpress blog in it. I've installed and configured PHP in IIS. I have tested the PHP handler by creating a separate site, everything works fine, phpinfo() gives the desired output. However, I'm having problem running the PHP files inside my Java web application. I've put my test PHP file inside a folder called blog. When I access this folder in the browser as /mysite/blog I get a 404 page from my Java application. When I try to invoke the php page directly, http://mysite/blog/index.php, I get an unprocessed php page. I'm using isapi_handler for the reidrects. How do I tell my isapi_handler to ignore /blog folder? In my IIS handler mapping, *.php is mapped with Fast CGI. I'm not sure how to approach this problem and any help on this would be much appreciated. Thanks in advance.

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• WYSIWYG with Qt - font size woes

  - by Rob

  I am creating a custom Qt widget that mimics an A4 printed page and am having problems getting fonts to render at the correct size. My widget uses QPainter::setViewport and QPainter::setWindow to mimic the A4 page, using units of 10ths of a millimetre which enables me to draw easily. However, attempting to create a font at a specific point size doesn't seem to work and using QFont:setPixelSize isn't accurate. Here is some code: View::View(QWidget *parent) : QWidget(parent), printer(new QPrinter) { printer->setPaperSize(QPrinter::A4); printer->setFullPage(true); } void View::paintEvent(QPaintEvent*) { QPainter painter(this); painter.setWindow(0, 0, 2100, 2970); painter.setViewport(0, 0, printer->width(), printer->height()); // Draw a rect at x = 1cm, y = 1cm, 6cm wide and 1 inch high painter.drawRect(100, 100, 600, 254); // Create a 72pt (1 inch) high font QFont font("Arial"); font.setPixelSize(254); painter.setFont(font); // Draw in the same box // The font is too large painter.drawText(QRect(100, 100, 600, 254), tr("Wg\u0102")); // Ack - the actual font size reported by the metrics is 283 pixels! const QFontMetrics fontMetrics = painter.fontMetrics(); qDebug() << "Font height = " << fontMetrics.height(); } So I'm asking for a 254 high font (1 inch, 72 pts) and it's too big and sure enough when I query for the font height via QFontMetrics it is 283 high. Does anyone else know how to use font sizes in points when using custom mapping modes like this? It must be possible. Note that I cannot see how to convert between logical/device points either (i.e. the Win32 DPtoLP/LPtoDP equivalents.)

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• Why is my simple python gtk+cairo program running so slowly/stutteringly?

  - by synapz

  My program draws circles moving on the window. I think I must be missing some basic gtk/cairo concept because it seems to be running too slowly/stutteringly for what I am doing. Any ideas? Thanks for any help! #!/usr/bin/python import gtk import gtk.gdk as gdk import math import random import gobject # The number of circles and the window size. num = 128 size = 512 # Initialize circle coordinates and velocities. x = [] y = [] xv = [] yv = [] for i in range(num): x.append(random.randint(0, size)) y.append(random.randint(0, size)) xv.append(random.randint(-4, 4)) yv.append(random.randint(-4, 4)) # Draw the circles and update their positions. def expose(*args): cr = darea.window.cairo_create() cr.set_line_width(4) for i in range(num): cr.set_source_rgb(1, 0, 0) cr.arc(x[i], y[i], 8, 0, 2 * math.pi) cr.stroke_preserve() cr.set_source_rgb(1, 1, 1) cr.fill() x[i] += xv[i] y[i] += yv[i] if x[i] > size or x[i] < 0: xv[i] = -xv[i] if y[i] > size or y[i] < 0: yv[i] = -yv[i] # Self-evident? def timeout(): darea.queue_draw() return True # Initialize the window. window = gtk.Window() window.resize(size, size) window.connect("destroy", gtk.main_quit) darea = gtk.DrawingArea() darea.connect("expose-event", expose) window.add(darea) window.show_all() # Self-evident? gobject.idle_add(timeout) gtk.main()

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• Good way to allow people to select a lot of things?

  - by jphenow

  I'm using jQuery, ASP.NET, SQL Server, and the other usual suspects to design a company CRM. After they put in contact info, notes, dates, places and so forth they have to be able to select many different people to be "CC'ed." A group of people will be required to be one either "CC'ed" or "ToDo." The rest of the people can be nothing or "CC" or "ToDo." Currently we have it set up as a huge databind to templates with radio buttons for each option. Looks like shit. Anyone have any suggestions? I'd like to use a template with a datasource and have a good way to retrieve their answers and use them. I'm leaning jQuery direction but like I said I'll need there to be up to 3 possible options for the people. This is going to be all opinion so I'm just looking for options. Just to re-clarify, this concept is similar to email but I don't want them to have to type anything in as it is a set group of names that they're allowed to select from. Looking for quick simple and pretty. somewhere in the range of 120 names.

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• Symfony Form render with Self Referenced Entity

  - by benarth

  I have an Entity containing Self-Referenced mapping. class Category { /** * @var integer * * @ORM\Column(name="id", type="integer") * @ORM\Id * @ORM\GeneratedValue(strategy="AUTO") */ private $id; /** * @var string * * @ORM\Column(name="name", type="string", length=100) */ private $name; /** * @ORM\OneToMany(targetEntity="Category", mappedBy="parent") */ private $children; /** * @ORM\ManyToOne(targetEntity="Category", inversedBy="children") * @ORM\JoinColumn(name="parent_id", referencedColumnName="id") */ private $parent; } In my CategoryType I have this : public function buildForm(FormBuilderInterface $builder, array $options) { $plan = $this->plan; $builder->add('name'); $builder->add('parent', 'entity', array( 'class' => 'xxxBundle:Category', 'property' => 'name', 'empty_value' => 'Choose a parent category', 'required' => false, 'query_builder' => function(EntityRepository $er) use ($plan) { return $er->createQueryBuilder('u') ->where('u.plan = :plan') ->setParameter('plan', $plan) ->orderBy('u.id', 'ASC'); }, )); } Actually, when I render the form field Category this is something like Cat1 Cat2 Cat3 Subcat1 Subcat2 Cat4 I would like to know if it's possible and how to display something more like, a kind of a simple tree representation : Cat1 Cat2 Cat3 -- Subcat1 -- Subcat2 Cat4 Regards.

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• How can I have 2 ADO access methods use the same Transaction?

  - by KevinDeus

  I'm writing a test to see if my LINQ to Entity statement works.. I'll be using this for others if I can get this concept going.. my intention here is to INSERT a record with ADO, then verify it can be queried with LINQ, and then ROLLBACK the whole thing at the end. I'm using ADO to insert because I don't want to use the object or the entity model that I am testing. I figure that a plain ADO INSERT should do fine. problem is.. they both use different types of connections. is it possible to have these 2 different data access methods use the same TRANSACTION so I can roll it back?? _conn = new SqlConnection(_connectionString); _conn.Open(); _trans = _conn.BeginTransaction(); var x = new SqlCommand("INSERT INTO Table1(ID, LastName, FirstName, DateOfBirth) values('127', 'test2', 'user', '2-12-1939');", _conn); x.ExecuteNonQuery(); //So far, so good. Adding a record to the table. //at this point, we need to do **_trans.Commit()** here because our Entity code can't use the same connection. Then I have to manually delete in the TestHarness.TearDown.. I'd like to eliminate this step //(this code is in another object, I'll include it for brevity. Imagine that I passed the connection in) //check to see if it is there using (var ctx = new XEntities(_conn)) //can't do this.. _conn is not an EntityConnection! { var retVal = (from m in ctx.Table1 where m.first_name == "test2" where m.last_name == "user" where m.Date_of_Birth == "2-12-1939" where m.ID == 127 select m).FirstOrDefault(); return (retVal != null); } //Do test.. Assert.BlahBlah(); _trans.Rollback();

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• Delete only reference to child object

  - by Al

  I'm running in to a bit of a problem where any attempt to delete just the reference to a child also deletes the child record. My schema looks like this Person Organisation OrganisationContacts : Person OrgId PersonId Role When removing an Organisation i want to only delete the record in OrgnaisationContacts, but not touch the Person record. My Mapping looks like this Code: public OrganisationMap() { Table("Organsations"); .... HasMany<OrganisationContact>(x => x.Contacts) .Table("OrganisationContacts ") .KeyColumn("OrgId") .Not.Inverse() .Cascade.AllDeleteOrphan(); } public class OrganisationContactMap : SubclassMap<OrganisationContact> { public OrganisationContactMap() { Table("OrganisationContacts"); Map(x => x.Role, "PersonRole"); Map(x => x.IsPrimary); } } At the moment just removing a contact from the IList either doesn't reflect in the database at all, or it issues two delete statements DELETE FROM OrganisationContact & DELETE FROM Person, or tries to set PersonId to null in the OrganisationContacts table. All of which are not desirable. Any help would be great appreciated.

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• Creating a RESTful API - HELP!

  - by Martin Cox

  Hi Chaps Over the last few weeks I've been learning about iOS development, which has naturally led me into the world of APIs. Now, searching around on the Internet, I've come to the conclusion that using the REST architecture is very much recommended - due to it's supposed simplicity and ease of implementation. However, I'm really struggling with the implementation side of REST. I understand the concept; using HTTP methods as verbs to describe the action of a request and responding with suitable response codes, and so on. It's just, I don't understand how to code it. I don't get how I map a URI to an object. I understand that a GET request for domain.com/api/user/address?user_id=999 would return the address of user 999 - but I don't understand where or how that mapping from /user/address to some method that queries a database has taken place. Is this all coded in one php script? Would I just have a method that grabs the URI like so: $array = explode("/", ltrim(rtrim($_SERVER['REQUEST_URI'], "/"), "/")) And then cycle through that array, first I would have a request for a "user", so the PHP script would direct my request to the user object and then invoke the address method. Is that what actually happens? I've probably not explained my thought process very well there. The main thing I'm not getting is how that URI /user/address?id=999 somehow is broken down and executed - does it actually resolve to code? class user(id) { address() { //get user address } } I doubt I'm making sense now, so I'll call it a day trying to explain further. I hope someone out there can understand what I'm trying to say! Thanks Chaps, look forward to your responses. Martin p.s - I'm not a developer yet, I'm learning :)

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• getting a "default" concrete class that implements an interface

  - by Roger Joys

  I am implementing a custom (and generic) Json.net serializer and hit a bump in the road that I could use some help on. When the deserializer is mapping to a property that is an interface, how can I best determine what sort of object to construct to deserialize to to place into the interface property. I have the following: [JsonConverter(typeof(MyCustomSerializer<foo>))] class foo { int Int1 { get; set; } IList<string> StringList {get; set; } } My serializer properly serializes this object, and but when it comes back in, and I try to map the json parts to to object, I have a JArray and an interface. I am currently instantiating anything enumerable like List as theList = Activator.CreateInstance(property.PropertyType); This works create to work with in the deserialization process, but when the property is IList, I get runtime complaints (obviously) about not being able to instantiate an interface. So how would I know what type of concrete class to create in a case like this? Thank you

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• PHP, MySQL prepared statements - can you use results of execute more than once by calling data_seek(

  - by Carvell Fenton

  Hello, I have a case where I want to use the results of a prepared statement more than once in a nested loop. The outer loop processes the results of another query, and the inner loop is the results of the prepared statement query. So the code would be something like this (just "pseudoish" to demonstrate the concept): // not showing the outer query, it is just a basic SELECT, not prepared statement // we'll call it $outer_query $obj_array = array(); // going to save objects in this $ids = array(18,19,20); // just example id numbers $query = "SELECT field1, field2 FROM table1 WHERE id=?"; $stmt = $db->prepare($query); foreach ($ids as $id) { $stmt->bind_param("i", $id); $stmt->execute(); $stmt->bind_result($var1, $var2); $stmt->store_result(); // I think I need this for data_seek while ($q1 = $outer_query->fetch_object()) { while ($stmt->fetch()) { if ($q1->field1 == $var1) { // looking for a match $obj = new stdClass(); $obj->var1 = $var1; $obj->var2 = $var2; $obj_array[] = $obj; $stmt->data_seek(0); // reset for outer loop break; // found match, so leave inner } } } } The problem I seem to be experiencing is that the values are not getting bound in the variables as I would expect after the first time I use fetch in the inner loop. Specifically, in one example I ran with 3 ids for the foreach, the first id was processed correctly, the second was processed incorrectly (matches were not found in the inner loop even though they existed), and then the third was processed correctly. Is there something wrong with the prepared statment function calls in the sequence I am doing above, or is this an invalid way to use the results of the prepared statement? Thanks.

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• Facebook: Social Widgets versus Share

  - by just_wes

  Hello all, I am interested in people's thoughts on Facebook's new social widgets thing. Most notably the new "Like" button. The concept I am struggling with is the difference between "Like" and "Share". I have an existing Connect application. This application has its own fan page on Facebook. People can become "Fans" of the page and register to receive email updates and the like. The application is currently programmed to update its own fan page any time content is added to the site. Enter Social Widgets and "Like". People who visit our site can currently "share" our content on Facebook. With "Share" they can post a full item to their wall with a comment or send the content item as a message to another Facebook user. "Like" seems to do the same thing minus the message part. However "Like" automatically subscribes people to the fan page. My question is simply, should I add "Like" to my existing Connect site? Is "Like" different than what I already have? Are Social Widgets the future of Connect? Thanks!

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• Enum exeeding the 65535 bytes limit of static initializer... what's best to do?

  - by Daniel Bleisteiner

  I've started a rather large Enum of so called Descriptors that I've wanted to use as a reference list in my model. But now I've come across a compiler/VM limit the first time and so I'm looking for the best solution to handle this. Here is my error : The code for the static initializer is exceeding the 65535 bytes limit It is clear where this comes from - my Enum simply has far to much elements. But I need those elements - there is no way to reduce that set. Initialy I've planed to use a single Enum because I want to make sure that all elements within the Enum are unique. It is used in a Hibernate persistence context where the reference to the Enum is stored as String value in the database. So this must be unique! The content of my Enum can be devided into several groups of elements belonging together. But splitting the Enum would remove the unique safety I get during compile time. Or can this be achieved with multiple Enums in some way? My only current idea is to define some Interface called Descriptor and code several Enums implementing it. This way I hope to be able to use the Hibernate Enum mapping as if it were a single Enum. But I'm not even sure if this will work. And I loose unique safety. Any ideas how to handle that case?

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• Tagging in Subversion - how do I make the decision about continuing to work on my trunk vs. the new

  - by Howiecamp

  I'm running Tortoise SVN to manage a project. Obviously the principles around tagging apply to any implementation of SVN but in this question I'll be referring to some TortoiseSVN-specific dialog boxes and messages. My working directory and the subversion repository structure both have a Source root directory and the Trunk, Tags and Branches directories underneath. (I couldn't figure out how to do a multilevel indented hierarchy in markdown without using bullets, so if someone could edit and fix this I'd appreciate it.) I'm working out of the Trunk directory in my working copy and it's pointing at the Trunk directory in the repo. I want to apply a Tag "Release1" so I click the "Branch/tag..." menu option and set the repo path as my [repo_path/bla/Source/Tags/Release1" tag. This dialog box gives me the option to "Switch my working copy to new branch/tag". I understand that if this option is left unchecked, the new "Release1" branch under /Tags" will be created but my working copy will remain on the previous "Trunk" path. If I do check this option (or use the Switch command) I understand that my working copy will switch to the new "Release1" branch under "/Tags". Where I'm missing a concept is how to make this decision. It doesn't seem like I want to switch my working directory to the recently created tag since by definition (?) I want that tag to be a snapshot of my code as of a point in time. If I don't switch the working directory, I'll continue working off Trunk and when I'm ready to take another snapshot I'll make another tag. And so on... Am I understanding this right or am I stating something incorrectly in the previous paragraph (e.g. the statement about not wanting to switch to the tag since the tag should represent a point in time snapshot) or otherwise missing something regarding how to make this decision?

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• Best way to create a SPARQL endpoint for a RDBMS (MySQL database)

  - by Ankur

  I am doing (want to do) some experiments with Linked Open Datasets particularly those put out by governments. I have a RDBMS (more specifically MySQL). I designed it with semantic web ideas in mind i.e. I have a information stored as objects, predicates and classes which define objects. In turn all objects are related to each other though statements of the form subject -- predicate -- object (where the subjects are from the objects table). I want to be able to query other RDF triple stores from my application and let other triple stores query my data. Is it possible to "set something up" so that this is possible? I have looked at Jena. Using Jena seems to mean I have to it as a storage application rather than MySQL - the only problem with this is that I include a new concept called a category (which I don't think is part of the semantic web languages). I will use categories to help with displaying information (they don't have any other meaning) but using Jena seems to mean that I can't organise predicates under categories for more convenient viewing. I am using Java so a JAVA API is preferred. It's also possible I misunderstood the purpose of Jena, and maybe that can be of use, but I am not sure how. I am sure four days from now this question will seem rather silly, but at the moment I am somewhat confused about how to proceed.

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• [C#] Linq doesn't insert associated entity on insert.

  - by Tomek

  Hello! I have simple mapping: [Table(Name="Person")] public class Person { private int id; private int state_id; private EntityRef<PersonState> state = new EntityRef<PersonState>(); [Column(IsPrimaryKey = true, Storage = "id", Name="id", IsDbGenerated = true, CanBeNull = false)] public int ID { get { return id; } set { id = value; } } [Column(Storage="state_id", Name="state_id")] public int StateID { get{ return state_id;} set{ state_id = value;} } [Association( Storage = "state", ThisKey = "StateID", IsForeignKey=true)] public PersonState State { get { return state.Entity; } set { state.Entity = value; } } } [Table(Name = "PersonState")] public class PersonState { private int id; private State state; [Column(Name="id", Storage="id", IsDbGenerated=true, IsPrimaryKey=true)] public int ID { get { return id; } set { id = value; } } [Column(Name = "date", Storage = "date")] public DateTime Date { get { return date; } set { date = value; } } [Column(Name = "type", Storage = "state")] public State State { get { return state; } set { state = value; } } } I use this code to insert new person with default state: private static Person NewPerson() { Person p = new Person(); p.State = DefaultState(p); return p; } private static PersonState DefaultState() { PersonState state = new PersonState(); state.Date = DateTime.Now; state.State = State.NotNotified; state.Comment = "Default State!"; return state; } Leater in code: db.Persons.InsertOnSubmit(NewPerson()); db.SubmitChanges(); In database(sqlite) I have all new persons, but state_id of all persons is set to 0, and PersonState table is empty. Why Linq did not insert any State object to database?

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• How can I help fellow students struggling in programming classes?

  - by David Barry

  I'm a computer science student finishing up my second semester of programming classes. I've enjoyed them quite a bit, and learned a lot, but it seems other students are struggling with the concepts and assignments more than I am. When an assignment is due, the inevitable group email comes out the day or two before with people needing some help either with a specific part of the problem, or sometimes people just seem to have a hard time knowing where to start. I'd really like to be able to help out, but I have a hard time thinking of the right way to give them help without giving them the answer. When I'm having trouble understanding a concept, a code snippet can go along way to helping me, but at the same time if it makes a lot of sense, it can be difficult to think of another way to go about it. Plus the Academic Integrity section of each assignment is always looming overhead warning against sharing code with others. I've tried using pseudo code to help give others an idea on program flow, leaving them to figure out how to implement certain aspects of it, but I didn't get too much feedback and don't know how much it actually helped them out, or if it just confused them further. So I'm basically looking to see if anyone has experience with this, or good ways that I can help out other students to nudge them in the right direction or help them think about the problem in the right way.

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• Entity Framework 5 Enum Naming

  - by Tyrel Van Niekerk

  I am using EF 5 with migrations and code first. It all works rather nicely, but there are some issues/questions I would like to resolve. Let's start with a simple example. Lets say I have a User table and a user type table. The user type table is an enum/lookup table in my app. So the user table has a UserTypeId column and a foreign key ref etc to UserType. In my poco, I have a property called UserType which has the enum type. To add the initial values to the UserType table (or add/change values later) and to create the table in the initial migrator etc. I need a UserType table poco to represent the actual table in the database and to use in the map files. I mapped the UserType property in the User poco to UserTypeId in the UserType poco. So now I have a poco for code first/migrations/context mapping etc and I have an enum. Can't have the same name for both, so do I have a poco called UserType and something else for the enum or have the poco for UserType be UserTypeTable or something? More importantly however, am I missing some key element in how code first works? I tried the example above, ran Add-Migration and it does not add the lookup table for the enum.

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• PHP OOP: Avoid Singleton/Static Methods in Domain Model Pattern

  - by sunwukung

  I understand the importance of Dependency Injection and its role in Unit testing, which is why the following issue is giving me pause: One area where I struggle not to use the Singleton is the Identity Map/Unit of Work pattern (Which keeps tabs on Domain Object state). //Not actual code, but it should demonstrate the point class Monitor{//singleton construction omitted for brevity static $members = array();//keeps record of all objects static $dirty = array();//keeps record of all modified objects static $clean = array();//keeps record of all clean objects } class Mapper{//queries database, maps values to object fields public function find($id){ if(isset(Monitor::members[$id]){ return Monitor::members[$id]; } $values = $this->selectStmt($id); //field mapping process omitted for brevity $Object = new Object($values); Monitor::new[$id]=$Object return $Object; } $User = $UserMapper->find(1);//domain object is registered in Id Map $User->changePropertyX();//object is marked "dirty" in UoW // at this point, I can save by passing the Domain Object back to the Mapper $UserMapper->save($User);//object is marked clean in UoW //but a nicer API would be something like this $User->save(); //but if I want to do this - it has to make a call to the mapper/db somehow $User->getBlogPosts(); //or else have to generate specific collection/object graphing methods in the mapper $UserPosts = $UserMapper->getBlogPosts(); $User->setPosts($UserPosts); Any advice on how you might handle this situation? I would be loathe to pass/generate instances of the mapper/database access into the Domain Object itself to satisfy DI - At the same time, avoiding that results in lots of calls within the Domain Object to external static methods. Although I guess if I want "save" to be part of its behaviour then a facility to do so is required in its construction. Perhaps it's a problem with responsibility, the Domain Object shouldn't be burdened with saving. It's just quite a neat feature from the Active Record pattern - it would be nice to implement it in some way.

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