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  • Entity communication: Message queue vs Publish/Subscribe vs Signal/Slots

    - by deft_code
    How do game engine entities communicate? Two use cases: How would entity_A send a take-damage message to entity_B? How would entity_A query entity_B's HP? Here's what I've encountered so far: Message queue entity_A creates a take-damage message and posts it to entity_B's message queue. entity_A creates a query-hp message and posts it to entity_B. entity_B in return creates an response-hp message and posts it to entity_A. Publish/Subscribe entity_B subscribes to take-damage messages (possibly with some preemptive filtering so only relevant message are delivered). entity_A produces take-damage message that references entity_B. entity_A subscribes to update-hp messages (possibly filtered). Every frame entity_B broadcasts update-hp messages. Signal/Slots ??? entity_A connects an update-hp slot to entity_B's update-hp signal. Something better? Do I have a correct understanding of how these communication schemes would tie into a game engine's entity system? How do entities in commercial game engines communicate?

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  • Entity Framework 4 "Generate Database from Model" to SQLEXPRESS mdf results in "Could not locate ent

    - by InfinitiesLoop
    I'm using Visual Studio 2010 RTM. I want to do model-first, so I started a new MVC app and added a new blank edmx. Created a few entities. No problem. Then I "Generate Database from Model", and allow the dialog to create a new database for me, which it does successfully as 'mydatabase.mdf' in the app's App_Data directory. Then I open the generated sql file (in Visual Studio). To run it of course I have to give it a connection. I am not sure if it's right, but I used '.\SQLEXPRESS' and Windows authentication. No idea how I'd tell it where the MDF is. Then the problem -- upon executing it, I get: Msg 911, Level 16, State 1, Line 1 Could not locate entry in sysdatabases for database 'mydatabase'. No entry found with that name. Make sure that the name is entered correctly. And indeed there were no tables created in the MDF. So... what am I doing wrong, or am I off my rocker expecting this to work? :)

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  • generate only objectLayer of Entity Framework Model by edmgen tool

    - by loviji
    How to generate only objectLayer by edmgen tool, without generating csdl, ssdl and views ? *"%windir%\Microsoft.NET\Framework\v4.0.30319\edmgen.exe" /mode:fullgeneration /c:"Data Source=.\sqlexpress; Initial Catalog=uqs; Integrated Security=SSPI" /project:generateEntityModel /entitycontainer:uqsEntities /namespace:uqsModel /language:CSharp /outobjectlayer:"D:/uqsObjectLayer.cs" * in this script I don't write location to write csdl, ssdl and views , but they are generated in C:\Users\adminUser in windows Vista and objectLayer generated to D:/uqsObjectLayer.cs. If I use /mode:EntityClassGeneration, this option requires the /incsdl argument and either the /project argument or the /outobjectlayer argument. The /language argument is optional. But I don't want use csdl file. As I understand, edmgen.tool can not create objectlayer without csdl file. Now is there alternate way or tool for generating objectlayer from db?

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  • UDF call in entity framework is cached

    - by Fred Yang
    I am doing a test after reading an article http://blogs.msdn.com/alexj/archive/2009/08/07/tip-30-how-to-use-a-custom-store-function.aspx about udf function called. When I use a function with objectContext.Entities.Where( t= udf(para1, para2) == 1), here the Entities is not ObjectQuery, but an ObjectSet, the first time I call the method, it runs correctly, if I reuse the objectContext,and run it again but with different para1, para2, then the previous parameter values still cached, and the result is same as previous one, which is wrong. The sql profiler shows that both query hit the database, but the t-sql is the same. Am I missing something? And the ObjectSet does not support .where(esql_string). How to get udf working with ObjectSet? Thanks Fred

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  • Error reached after genereated entity framework classes by edmgen tool

    - by loviji
    Hello, First I read this question, but this knowledge did not help to solve my problems. In initial I've created edmx file by Visual Studio. Generated files with names: uqsModel.Designer.cs uqsModel.edmx This files are located on App_Code folder. And my web app work normally. In Web Config generated connectionstring automatically. <add name="uqsEntities" connectionString="metadata=res://*/App_Code.uqsModel.csdl|res://*/App_Code.uqsModel.ssdl|res://*/App_Code.uqsModel.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=aemloviji\sqlexpress;Initial Catalog=uqs;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient" /></connectionStrings> Then I had to generate classes by the instrument edmgen tool(full generation mode). Generated new files with names: uqsModel.cs uqsModel.csdl uqsModel.msl uqsModel.ssdl uqsViews.cs it save new classed to the folder where edmx files located before, and remove existing edmx files. And when page redirrects to any web page server side code fails. And problem: Unable to load the specified metadata resource. Some idea, please.

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  • Entity Framework - Optimistic Concurrency Issue

    - by Cranialsurge
    I have a windows service that runs every 10 seconds ... each time it runs, it takes some test data, modifies it and persists it to the database using the EntityFramework. However, on every second run, when I try to persist the change I get the following Optimistic Concurrency Exception:- Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries I know for a fact that there is nothing else writing to that DB but my service which updates records every 10 seconds. What could be causing the concurrency exception here ?

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  • Entity Framework - MySQL - Datetime format issue

    - by effkay
    Hello; I have a simple table with few date fields. Whenever I run following query: var docs = ( from d in base.EntityDataContext.document_reviews select d ).ToList(); I get following exception: Unable to convert MySQL date/time value to System.DateTime. MySql.Data.Types.MySqlConversionException: Unable to convert MySQL date/time value to System.DateTime The document reviews table has two date/time fields. One of them is nullable. I have tried placing following in connection string: Allow Zero Datetime=true; But I am still getting exception. Anyone with a solution?

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  • Unable to specify abstract classes in TPH hierarchy in Entity Framework 4

    - by Lee Atkinson
    Hi I have a TPH heirachy along the lines of: A-B-C-D A-B-C-E A-F-G-H A-F-G-I I have A as Abstract, and all the other classes are concrete with a single discriminator column. This works fine, but I want C and G to be abstract also. If I do that, and remove their discriminators from the mapping, I get error 3034 'Two entities with different keys are mapped to the same row'. I cannot see how this statement can be correct, so I assume it's a bug in some way. Is it possible to do the above? Lee

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  • Entity Relationship Multiple 1:1's

    - by Evan
    I have an application where I have a generic object (table) called Hull. Each hull in the table is unique. I have another object that has three hulls, but they are specifically the Port_Hull, Center_Hull and Starboard_Hull. Rather than create a One to Many relationship, I was trying to create a one to one relationship for each one, but this results in numerous errors unless I make the relationship from Hull to Vessel one to many (which it is not). Any idea how I go about this, or should I abandon the concept and make the vessel to hull relationship one to many and deal with lists that always have three entries? p.s. Using uniqueidentifiers as many users can be adding records while disconnected. Hull Table HullID uniqueidentifier (primary key) plus bunch of hull data fields Vessel Table VesselID uniqueidentifier (primary key) MainHullID uniqueidentifier (tried as key and non-key) PortHullID uniqueidentifier StarboardHullID uniqueidentifier plus bunch of Vessel data fields

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  • override delete function in entity framework

    - by k0ni
    How can i make my own delete method to prevent that the data really gets deleted? i want to set a datetime field when it gets deleted insted of a normal delete. i read about overriding the submitchanges function, but i don't get it to work thanks

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  • How to create relationship between two tables with revisions using Entity Framework

    - by Chris Ridenour
    So I am in the process of redesigning a small database (and potentially a much larger one) but want to show the value of using revisions / history of the business objects. I am switching the data from Access to MSSQL 2008. I am having a lot of internal debate on what version of "revision history" to use in the design itself - and thought I had decided to add a "RevisionId" to all tables. With this design - adding a RevisionId to all tables we would like tracked - what would be the best way to create Navigational Properties and Relationships between two tables such as | Vendor | VendorContact | where a Vendor can have multiple contacts. The Contacts themselves will be under revision. Will it require custom extensions or am I over thinking this? Thanks in advance.

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  • DeleteObject method is missing in Entity Framework 4.1

    - by bobetko
    This is driving me crazy. I am getting error that object doesn't contain definition for DeleteObject. Here is my line of code that produces an error: ctx.Tanks.DeleteObject(Tank); I tried to reference another object from another edmx file that my friend has created and then everything is fine, DeleteObject exists. I don't think I miss any references in my project. And project itself contains edmx file and I used DBContext to create POCOs. Any ideas?

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  • Missing something with Entity Framework for .NET 3.5?

    - by AC
    Is it not possible to have EF create the necessary entities when I have two related tables linked with a FK in .NET3.5SP1? I see where the checkbox to support this is disabled but it is available in .NET4. I've got a DB that has only tables with relationships in it. I need to build a Silverlight app (SL4) that allows management of the data within this app. I can't use .NET4 on the server... only .NET3.5SP1 so FK relationship bit in EF4 isn't available to me. Looking to avoid building as much of the plumbing to get back to the DB from the SL4 app as possible...

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  • Entity Framework 4 - Delete Object

    - by GibboK
    I have 3 Tables in my DataBase CmsMasterPages CmsMasterPagesAdvSlots (Pure Juction Table) CmsAdvSlots Here a Picture of my EDM: I need find out all objects CmsAdvSlot connected with a CmsMasterPage (it is working in my code posted belove), and DELETE the result (CmsAdvSlot) from the DataBase. My Problem is I am not able to DELETE this Objects when I found theme. Error: The object cannot be deleted because it was not found in the ObjectStateManager. int findMasterPageId = Convert.ToInt32(uxMasterPagesListSelector.SelectedValue); CmsMasterPage myMasterPage = context.CmsMasterPages.FirstOrDefault(x => x.MasterPageId == findMasterPageId); var resultAdvSlots = myMasterPage.CmsAdvSlots; // It is working until here foreach (var toDeleteAdv in resultAdvSlots) { context.DeleteObject(myMasterPage.CmsAdvSlots.Any()); // ERORR HERE!! context.SaveChanges(); } Any idea how to solve it? Thanks for your time! :-)

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  • Entity Framework 5 upgrade from 4

    - by user1714591
    I'm having an issue with the Where clause in a search, in my original version EF4 I could add a Where clause with 2 parameters, the where clause (string predicate) and a ObjectParameter list such as var query = context.entities.Where(WhereClause.ToString(), Params.ToArray()); since my upgrade to EF5 I don't seem to have that option am I missing something? This was originally used to build dynamic where clause such as "it.entity_id = @entity_id" then holding the variable value in the ObjectParameter. I'm hoping I don't have to rewrite all the searches that have been built out this way, so any assistance would be greatly appreciated. Cheers

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  • Entity Framework 4.0 GetChanges() equivalent

    - by Jonathan
    Hi In LINQ to SQL, you can override SubmitChanges and use the method this.GetChangeSet() to get all the inserts, updates and deletes so that you can make last minute changes before it is committed to the database. Can this be done in EF 4.0? I see there is a override for SaveChanges but I need to know the equivalent for GetChangeSet()

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  • How to get around the Circular Reference issue with JSON and Entity

    - by DanScan
    I have been experimenting with creating a website that leverages MVC with JSON for my presentation layer and Entity framework for data model/database. My Issue comes into play with serializing my Model objects into JSON. I am using the code first method to create my database. When doing the code first method a one to many relationship (parent/child) requires the child to have a reference back to the parent. (Example code my be a typo but you get the picture) class parent { public List<child> Children{get;set;} public int Id{get;set;} } class child { public int ParentId{get;set;} [ForeignKey("ParentId")] public parent MyParent{get;set;} public string name{get;set;} } When returning a "parent" object via a JsonResult a circular reference error is thrown because "child" has a property of class parent. I have tried the ScriptIgnore attribute but I lose the ability to look at the child objects. I will need to display information in a parent child view at some point. I have tried to make base classes for both parent and child that do not have a circular reference. Unfortunately when I attempt to send the baseParent and baseChild these are read by the JSON Parser as their derived classes (I am pretty sure this concept is escaping me). Base.baseParent basep = (Base.baseParent)parent; return Json(basep, JsonRequestBehavior.AllowGet); The one solution I have come up with is to create "View" Models. I create simple versions of the database models that do not include the reference to the parent class. These view models each have method to return the Database Version and a constructor that takes the database model as a parameter (viewmodel.name = databasemodel.name). This method seems forced although it works. NOTE:I am posting here because I think this is more discussion worthy. I could leverage a different design pattern to over come this issue or it could be as simple as using a different attribute on my model. In my searching I have not seen a good method to overcome this problem. My end goal would be to have a nice MVC application that heavily leverages JSON for communicating with the server and displaying data. While maintaining a consistant model across layers (or as best as I can come up with).

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  • Entity Framework - Self Tracking Objects - how to reset client side?

    - by David
    I am using wcf with self tracking entity framework objects. On the client side i have bound an entity to an edit form (which has multiple textboxes and comboboxes). After the user hits Save, the entity is sent through wcf to the server wcf service which will attempt to save the entity. If there is a failure (say a network failure), I need to reset the current entity back to original values. How best can I do this client side? (I recognize with Self Tracking objects there is a property OriginalValues however that collection seems to have count=0) so not sure how to get the original values? Thanks-

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  • Extracting the Date from a DateTime in Entity Framework 4 and LINQ

    - by Ken Cox [MVP]
    In my current ASP.NET 4 project, I’m displaying dates in a GridDateTimeColumn of Telerik’s ASP.NET Radgrid control. I don’t care about the time stuff, so my DataFormatString shows only the date bits: <telerik:GridDateTimeColumn FilterControlWidth="100px"   DataField="DateCreated" HeaderText="Created"    SortExpression="DateCreated" ReadOnly="True"    UniqueName="DateCreated" PickerType="DatePicker"    DataFormatString="{0:dd MMM yy}"> My problem was that I couldn’t get the built-in column filtering (it uses Telerik’s DatePicker control) to behave.  The DatePicker assumes that the time is 00:00:00 but the data would have times like 09:22:21. So, when you select a date and apply the EqualTo filter, you get no results. You would get results if all the time portions were 00:00:00. In essence, I wanted my Entity Framework query to give the DatePicker what it wanted… a Date without the Time portion. Fortunately, EF4 provides the TruncateTime  function. After you include Imports System.Data.Objects.EntityFunctions You’ll find that your EF queries will accept the TruncateTime function. Here’s my routine: Protected Sub RadGrid1_NeedDataSource _     (ByVal source As Object, _      ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) _     Handles RadGrid1.NeedDataSource     Dim ent As New OfficeBookDBEntities1     Dim TopBOMs = From t In ent.TopBom, i In ent.Items _                   Where t.BusActivityID = busActivityID _       And i.BusActivityID And t.ItemID = i.RecordID _       Order By t.DateUpdated Descending _       Select New With {.TopBomID = t.TopBomID, .ItemID = t.ItemID, _                        .PartNumber = i.PartNumber, _                        .Description = i.Description, .Notes = t.Notes, _                        .DateCreated = TruncateTime(t.DateCreated), _                        .DateUpdated = TruncateTime(t.DateUpdated)}     RadGrid1.DataSource = TopBOMs End Sub Now when I select March 14, 2011 on the DatePicker, the filter doesn’t stumble on time values that don’t make sense. Full Disclosure: Telerik gives me (and other developer MVPs) free copies of their suite.

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  • Entity Framework 4.0: Creating objects of correct type when using lazy loading

    - by DigiMortal
    In my posting about Entity Framework 4.0 and POCOs I introduced lazy loading in EF applications. EF uses proxy classes for lazy loading and this means we have new types in that come and go dynamically in runtime. We don’t have these types available when we write code but we cannot forget that EF may expect us to use dynamically generated types. In this posting I will give you simple hint how to use correct types in your code. The background of lazy loading and proxy classes As a first thing I will explain you in short what is proxy class. Business classes when designed correctly have no knowledge about their birth and death – they don’t know how they are created and they don’t know how their data is persisted. This is the responsibility of object runtime. When we use lazy loading we need a little bit different classes that know how to load data for properties when code accesses the property first time. As we cannot add this functionality to our business classes (they may be stored through more than one data access technology or by more than one Data Access Layer (DAL)) we create proxy classes that extend our business classes. If we have class called Product and product has lazy loaded property called Customer then we need proxy class, let’s say ProductProxy, that has same public signature as Product so we can use it INSTEAD OF product in our code. ProductProxy overrides Customer property. If customer is not asked then customer is null. But if we ask for Customer property then overridden property of ProductProxy loads it from database. This is how lazy loading works. Problem – two types for same thing As lazy loading may introduce dynamically generated proxy types we don’t know in our application code which type is returned. We cannot be sure that we have Product not ProductProxy returned. This leads us to the following question: how can we create Product of correct type if we don’t know the correct type? In EF solution is simple. Solution – use factory methods If you are using repositories and you are not using factories (imho it is pretty pointless with mapper) you can add factory methods to your EF based repositories. Take a look at this class. public class Event {     public int ID { get; set; }     public string Title { get; set; }     public string Location { get; set; }     public virtual Party Organizer { get; set; }     public DateTime Date { get; set; } } We have virtual member called Organizer. This property is virtual because we want to use lazy loading on this class so Organizer is loaded only when we ask it. EF provides us with method called CreateObject<T>(). CreateObject<T>() is member of ObjectContext class and it creates the object based on given type. In runtime proxy type for Event is created for us automatically and when we call CreateObject<T>() for Event it returns as object of Event proxy type. The factory method for events repository is as follows. public Event CreateEvent() {     var evt = _context.CreateObject<Event>();     return evt; } And we are done. Instead of creating factory classes we created factory methods that guarantee that created objects are of correct type. Conclusion Although lazy loading introduces some new objects we cannot use at design time because they live only in runtime we can write code without worrying about exact implementation type of object. This holds true until we have clean code and we don’t make any decisions based on object type. EF4.0 provides us with very simple factory method that create and return objects of correct type. All we had to do was adding factory methods to our repositories.

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  • Is it possible to auto update only selected properties on an existent entity object without touching the others

    - by LaserBeak
    Say I have a bunch of boolean properties on my entity class public bool isActive etc. Values which will be manipulated by setting check boxes in a web application. I will ONLY be posting back the one changed name/value pair and the primary key at a time, say { isActive : true , NewsPageID: 34 } and the default model binder will create a NewsPage object with only those two properties set. Now if I run the below code it will not only update the values for the properties that have been set on the NewsPage object created by the model binder but of course also attempt to null all the other non set values for the existent entity object because they are not set on NewsPage object created by the model binder. Is it possible to somehow tell entity framework not to look at the properties that are set to null and attempt to persist those changes back to the retrieved entity object and hence database ? Perhaps there's some code I can write that will only utilize the non-null values and their property names on the NewsPage object created by model binder and only attempt to update those particular properties ? [HttpPost] public PartialViewResult SaveNews(NewsPage Np) { Np.ModifyDate = DateTime.Now; _db.NewsPages.Attach(Np); _db.ObjectStateManager.ChangeObjectState(Np, System.Data.EntityState.Modified); _db.SaveChanges(); _db.Dispose(); return PartialView("MonthNewsData"); } I can of course do something like below, but I have a feeling it's not the optimal solution. Especially considering that I have like 6 boolean properties that I need to set. [HttpPost] public PartialViewResult SaveNews(int NewsPageID, bool isActive, bool isOnFrontPage) { if (isActive != null) { //Get entity and update this property } if (isOnFontPage != null) { //Get entity and update this property } }

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  • How to use batch rendering with an entity component system?

    - by Kiril
    I have an entity component system and a 2D rendering engine. Because I have a lot of repeating sprites (the entities are non-animated, the background is tile based) I would really like to use batch rendering to reduce calls to the drawing routine. What would be the best way to integrate this with an engtity system? I thought about creating and populating the sprite batche every frame update, but that will probably be very slow. A better way would be to add a reference to an entity's quad to the sprite batch at initialization, but that would mean that the entity factory has to be aware of the Rendering System or that the sprite batch has to be a component of some Cache entity. One case violates encapsulation pretty heavily, while the other forces a non-game object entity in the entity system, which I am not sure I like a lot. As for engine, I am using Love2D (Love2D website) and FEZ ( FEZ website) as entity system(so everything is in Lua). I am more interested in a generic pattern of how to properly implement that rather than a language/library specific solution. Thanks in advance!

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