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  • What are some arguments AGAINST using EntityFramework?

    - by Rachel
    The application I am currently building has been using Stored procedures and hand-crafted class models to represent database objects. Some people have suggested using Entity Framework and I am considering switching to that since I am not that far into the project. My problem is, I feel the people arguing for EF are only telling me the good side of things, not the bad side :) My main concerns are: We want Client-Side validation using DataAnnotations, and it sounds like I have to create the client-side models anyways so I am not sure that EF would save that much coding time We would like to keep the classes as small as possible when going over the network, and I have read that using EF often includes extra data that is not needed We have a complex database layer which crosses multiple databases, and I am not sure EF can handle this. We have one Common database with things like Users, StatusCodes, Types, etc and multiple instances of our main databases for different instances of the application. SELECT queries can and will query across all instances of the databases, however users can only modify objects that are in the database they are currently working on. They can switch databases without reloading the application. Object modes are very complex and there are often quite a few joins involved Arguments for EF are: Concurrency. I wouldn't have to code in checks to see if the record was updated before each save Code Generation. EF can generate partial class models and POCOs for me, however I am not positive this would really save me that much time since I think we would still need to create the client-side models for validation and some custom parsing methods. Speed of development since we wouldn't need to create the CRUD stored procedures for every database object Our current architecture consists of a WPF Service which handles database calls via parameterized Stored Procedures, POCO objects that go to/from the WCF service and the WPF client, and the WPF client itself which transforms POCOs into class Models for the purpose of Validation and DataBinding.

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  • Doing powerups in a component-based system

    - by deft_code
    I'm just starting really getting my head around component based design. I don't know what the "right" way to do this is. Here's the scenario. The player can equip a shield. The the shield is drawn as bubble around the player, it has a separate collision shape, and reduces the damage the player receives from area effects. How is such a shield architected in a component based game? Where I get confused is that the shield obviously has three components associated with it. Damage reduction / filtering A sprite A collider. To make it worse different shield variations could have even more behaviors, all of which could be components: boost player maximum health health regen projectile deflection etc Am I overthinking this? Should the shield just be a super component? I really think this is wrong answer. So if you think this is the way to go please explain. Should the shield be its own entity that tracks the location of the player? That might make it hard to implement the damage filtering. It also kinda blurs the lines between attached components and entities. Should the shield be a component that houses other components? I've never seen or heard of anything like this, but maybe it's common and I'm just not deep enough yet. Should the shield just be a set of components that get added to the player? Possibly with an extra component to manage the others, e.g. so they can all be removed as a group. (accidentally leave behind the damage reduction component, now that would be fun). Something else that's obvious to someone with more component experience?

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  • Doing powerups in a component-based system

    - by deft_code
    I'm just starting really getting my head around component based design. I don't know what the "right" way to do this is. Here's the scenario. The player can equip a shield. The the shield is drawn as bubble around the player, it has a separate collision shape, and reduces the damage the player receives from area effects. How is such a shield architected in a component based game? Where I get confused is that the shield obviously has three components associated with it. Damage reduction / filtering A sprite A collider. To make it worse different shield variations could have even more behaviors, all of which could be components: boost player maximum health health regen projectile deflection etc Am I overthinking this? Should the shield just be a super component? I really think this is wrong answer. So if you think this is the way to go please explain. Should the shield be its own entity that tracks the location of the player? That might make it hard to implement the damage filtering. It also kinda blurs the lines between attached components and entities. Should the shield be a component that houses other components? I've never seen or heard of anything like this, but maybe it's common and I'm just not deep enough yet. Should the shield just be a set of components that get added to the player? Possibly with an extra component to manage the others, e.g. so they can all be removed as a group. (accidentally leave behind the damage reduction component, now that would be fun). Something else that's obvious to someone with more component experience?

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  • Proper method to update and draw from game loop?

    - by Lost_Soul
    Recently I've took up the challenge for myself to create a basic 2d side scrolling monster truck game for my little brother. Which seems easy enough in theory. After working with XNA it seems strange jumping into Java (which is what I plan to program it in). Inside my game class I created a private class called GameLoop that extends from Runnable, then in the overridden run() method I made a while loop that handles time and such and I implemented a targetFPS for drawing as well. The loop looks like this: @Override public void run() { long fpsTime = 0; gameStart = System.currentTimeMillis(); lastTime = System.currentTimeMillis(); while(game.isGameRunning()) { currentTime = System.currentTimeMillis(); long ellapsedTime = currentTime - lastTime; if(mouseState.leftIsDown) { que.add(new Dot(mouseState.getPosition())); } entities.addAll(que); game.updateGame(ellapsedTime); fpsTime += ellapsedTime; if(fpsTime >= (1000 / targetedFPS)) { game.drawGame(ellapsedTime); } lastTime = currentTime; } The problem I've ran into is adding of entities after a click. I made a class that has another private class that extends MouseListener and MouseMotionListener then on changes I have it set a few booleans to tell me if the mouse is pressed or not which seems to work great but when I add the entity it throws a CME (Concurrent Modification Exception) sometimes. I have all the entities stored in a LinkedList so later I tried adding a que linkedlist where I later add the que to the normal list in the update loop. I think this would work fine if it was just the update method in the gameloop but with the repaint() method (called inside game.drawGame() method) it throws the CME. The only other thing is that I'm currently drawing directly from the overridden paintComponent() method in a custom class that extends JPanel. Maybe there is a better way to go about this? As well as fix my CME? Thanks in advance!!!

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  • Architecture : am I doing things right?

    - by Jeremy D
    I'm trying to use a '~classic' layered arch using .NET and Entity Framework. We are starting from a legacy database which is a little bit crappy: Inconsistent naming Unneeded views (view referencing other views, select * views etc...) Aggregated columns Potatoes and Carrots in the same table etc... So I ended with fully isolating my database structure from my domain model. To do so EF entities are hidden from presentation layer. The goal is to permit an easier database refactoring while lowering the impact of it on applications. I'm now facing a lot of challenges and I'm starting to ask myself if I'm doing things right. My Domain Model is highly volatile, it keeps evolving with apps as new fields needs are arising. Complexity of it keeps raising and class it contains start to get a lot of properties. Creating include strategy and reprojecting to EF is very tricky (my domain objects don't have any kind of lazy/eager loading relationship properties): DomainInclude<Domain.Model.Bar>.Include("Customers").Include("Customers.Friends") // To... IFooContext.Bars.Include(...).Include(...).Where(...) Some framework are raping the isolation levels (Devexpress Grids which needs either XPO or IQueryable for filtering and paging large data sets) I'm starting to ask myself if : the isolation of EF auto-generated entities is an unneeded cost. I should allow frameworks to hit IQueryable? Slow slope to hell? (it's really hard to isolate DevExpress framework, any successful experience?) the high volatility of my domain model is normal? Did you have similar difficulties? Any advice based on experience?

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  • Silverlight Developer needs ASP.NET MVC Training [on hold]

    - by Peet Brits
    With Silverlight on the way out, our company wants to embrace HTML5 and related technologies. Background: Our Silverlight project did everything from generating its own models (or data contracts), sending it over WCF, tracking changes, with a whole deal of back-end code to make the ride smoother, but often also cluttered and more complex. Most of the original developers for this project are gone, and we want to embrace something new for future projects. Having done this very useful MVC Jump Start course at Microsoft Virtual Academy, we are all fired up for the next project. The problem is that we have very little in-depth knowledge of all the many different components. The most important hereof is probably Entity Framework, and (for later) Web API. I suppose the best place to start is at the Microsoft ASP.NET websites. Are there any other suggestions for learning from more experienced developers? I am a senior developer, but my knowledge of ASP.NET MVC (and related) is very limited. PS: We have a project deadline at the end of this month.

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  • Correct way to inject dependencies in Business logic service?

    - by Sri Harsha Velicheti
    Currently the structure of my application is as below Web App -- WCF Service (just a facade) -- Business Logic Services -- Repository - Entity Framework Datacontext Now each of my Business logic service is dependent on more than 5 repositories ( I have interfaces defined for all the repos) and I am doing a Constructor injection right now(poor mans DI instead of using a proper IOC as it was determined that it would be a overkill for our project). Repositories have references to EF datacontexts. Now some of the methods in the Business logic service require only one of the 5 repositories, so If I need to call that method I would end up instantiating a Service which will instatiate all 5 repositories which is a waste. An example: public class SomeService : ISomeService { public(IFirstRepository repo1, ISecondRepository repo2, IThirdRepository repo3) {} // My DoSomething method depends only on repo1 and doesn't use repo2 and repo3 public DoSomething() { //uses repo1 to do some stuff, doesn't use repo2 and repo3 } public DoSomething2() { //uses repo2 and repo3 to do something, doesn't require repo1 } public DoSomething3() { //uses repo3 to do something, doesn't require repo1 and repo2 } } Now if my I have to use DoSomething method on SomeService I end up creating both IFirstRepository,ISecondRepository and IThirdRepository but using only IFirstRepository, now this is bugging me, I can seem to accept that I am un-necessarily creating repositories and not using them. Is this a correct design? Are there any better alternatives? Should I be looking at Lazy instantiation Lazy<T> ?

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  • how can I code a recursive query in an Entity Framework model?

    - by Greg
    Hi, I have a model which includes NODES, and RELATIONSHIPS (that tie the nodes together, via a parent_node, child_node arrangement). Q1 - Is there any way in EF / Linq-to-entities to perform a query on nodes (e.g. context.Nodes..) to find say "all parents" or "or children" in the graph? Q2 - If there's not in Linq-to-entities, is there any other way to do this other than writing a method that manually goes through and doing it? Q3 - If manual is the only way to do it, should I be concerned about the number of database hits that will be going out to the database as the method keeps recursing through the data? Or more specifically, is there any EF caching type feature that might assist here in ensuring the method is performance from a "number of database hits" point of view? thanks thanks

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  • Entity Framework - Using Transactions or SaveChanges(false) and AcceptAllChanges()?

    - by mark smith
    Hi there, I have been investigating transactions and it appears that they take call of them selves in EF as long as i pass false to savechanges.. SaveChanges(false) and if all goes well then AcceptAllChanges() Question is what is something goes bad, don't have to rollback? or as soon as the my method goes out of scope its ended? What happens to any indentiy columns that were assigned half way through the transaction.. i presume if somebody else added a record after mine before mine went bad then this means there will be a missing Identity value. Is there any reason to use standard "transactionScope" in code? ideas? - thanks

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  • Where are the Entity Framework t4 templates for Data Annotations?

    - by JK
    I have been googling this non stop for 2 days now and can't find a single complete, ready to use, fully implemented t4 template that generates DataAnnotations. Do they even exist? I generate POCOs with the standard t4 templates. The actual database table has metadata that describes some of the validation rules, eg not null, nvarchar(25), etc. So all I want is a t4 template that can take my table and generate a POCO with DataAnnotations, eg public class Person { [Required] [StringLength(255)] public FirstName {get;set} } It is a basic and fundamental requirement, surely I can not be the first person in the entire world to have this requirement? I don't want to re-invent the wheel here. Yet I haven't found it after search high and low for days. This must be possible (and hopefully must be available somewhere to just download) - it would be criminally wrong to have to manually type in these annotations when the metadata for them already exists in the database.

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  • How to solve out of memory exception error in Entity FramWork?

    - by programmerist
    Hello; these below codes give whole data of my Rehber datas. But if i want to show web page via Gridview send me out of memory exception error. GenoTip.BAL: public static List<Rehber> GetAllDataOfRehber() { using (GenoTipSatisEntities genSatisCtx = new GenoTipSatisEntities()) { ObjectQuery<Rehber> rehber = genSatisCtx.Rehber; return rehber.ToList(); } } if i bind data directly dummy gridview like that no problem occures every thing is great!!! <asp:GridView ID="gwRehber" runat="server"> </asp:GridView> if above codes send data to Satis.aspx page: using GenoTip.BAL; namespace GenoTip.Web.ContentPages.Satis { public partial class Satis : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { gwRehber.DataSource = SatisServices.GetAllDataOfRehber(); gwRehber.DataBind(); //gwRehber.Columns[0].Visible = false; } } } } but i rearranged my gridview send me out of memory exception!!!! i need this arrangenment to show deta!!! <asp:GridView ID="gwRehber" runat="server"> <Columns> <%-- <asp:TemplateField> <ItemTemplate> <asp:Button runat="server" ID="btnID" CommandName="select" CommandArgument='<%# Eval("ID") %>' Text="Seç" /> </ItemTemplate> </asp:TemplateField>--%> <asp:BoundField DataField="Ad" HeaderText="Ad" /> <asp:BoundField DataField="BireyID" HeaderText="BireyID" Visible="false" /> <asp:BoundField DataField="Degistiren" HeaderText="Degistiren" /> <asp:BoundField DataField="EklemeTarihi" HeaderText="EklemeTarihi" /> <asp:BoundField DataField="DegistirmeTarihi" HeaderText="Degistirme Tarihi" Visible="false" /> <asp:BoundField DataField="Ekleyen" HeaderText="Ekleyen" /> <asp:BoundField DataField="ID" HeaderText="ID" Visible="false" /> <asp:BoundField DataField="Imza" HeaderText="Imza" /> <asp:BoundField DataField="KurumID" HeaderText="KurumID" Visible="false" /> </Columns> </asp:GridView> Error Detail : [OutOfMemoryException: 'System.OutOfMemoryException' türünde özel durum olusturuldu.] System.String.GetStringForStringBuilder(String value, Int32 startIndex, Int32 length, Int32 capacity) +29 System.Convert.ToBase64String(Byte[] inArray, Int32 offset, Int32 length, Base64FormattingOptions options) +146 System.Web.UI.ObjectStateFormatter.Serialize(Object stateGraph) +183 System.Web.UI.ObjectStateFormatter.System.Web.UI.IStateFormatter.Serialize(Object state) +4 System.Web.UI.Util.SerializeWithAssert(IStateFormatter formatter, Object stateGraph) +37 System.Web.UI.HiddenFieldPageStatePersister.Save() +79 System.Web.UI.Page.SavePageStateToPersistenceMedium(Object state) +105 System.Web.UI.Page.SaveAllState() +236 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1099

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  • Help with entity frame work error. Error 0194: All artifacts loaded....

    - by Steve
    This is a c#/asp.net project. The full error message I get is:Error 0194: All artifacts loaded into the item collection must have the same version. Multiple versions were encountered. This project was started as a 3.5 and upgraded to 4.0. When I try to test any of the methods I get the error that I posted in the subject line. I am going to include the actual lines that it throws the exception on. If there is anything in people need to see to try to help let me know and I post it as well. Any help will be appreciated, I am having no luck with this. /// /// Initializes a new SFBExternalPaymentsEntities object using the connection string found in the 'SFBExternalPaymentsEntities' section of the application configuration file. /// public SFBExternalPaymentsEntities() : base("name=SFBExternalPaymentsEntities", "SFBExternalPaymentsEntities") { this.ContextOptions.LazyLoadingEnabled = false; OnContextCreated(); } /// /// Initialize a new SFBExternalPaymentsEntities object. /// public SFBExternalPaymentsEntities(string connectionString) : base(connectionString, "SFBExternalPaymentsEntities") { this.ContextOptions.LazyLoadingEnabled = false; OnContextCreated(); } /// /// Initialize a new SFBExternalPaymentsEntities object. /// public SFBExternalPaymentsEntities(EntityConnection connection) : base(connection, "SFBExternalPaymentsEntities") { this.ContextOptions.LazyLoadingEnabled = false; OnContextCreated(); } endregion

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  • JPA Entity (in multiple persistence-unit) in OSGi (Spring DM) Environnement is confusing me.

    - by Vincent Demeester
    Hi, I'm a bit confused about a strange behavior of my JPA's related objects. I have three bundle : The User bundle does contain some user-related objects, but mainly the User object. The Energy bundle does contain some energy-related objects, and particularly a ConsumptionTerminal which contains a List of User. The Index bundle does contain an Index object that has no dependency at all. My OSGi environment is the following : A DataSource bundle that provide 2 services : dataSource and jpaVendorAdapter. The three bundles. They consume dataSource and jpaVendorAdapter. Their module-context.xml file look like : And they all have a persistence.xml file : User <?xml version="1.0" encoding="UTF-8"?> <persistence> <persistence-unit name="securityPU" transaction-type="JTA"> <jta-data-source>java:/securityDataSourceService</jta-data-source> <class>net.nextep.amundsen.security.domain.User</class> <!-- [...] --> <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <property name="eclipselink.logging.level" value="INFO" /> <property name="eclipselink.ddl-generation" value="create-tables" /> <property name="eclipselink.ddl-generation.output-mode" value="database" /> <property name="eclipselink.orm.throw.exceptions" value="true" /> </properties> </persistence-unit> </persistence> Energy <?xml version="1.0" encoding="UTF-8"?> <persistence> <persistence-unit name="energyPU" transaction-type="JTA"> <jta-data-source>java:/securityDataSourceService</jta-data-source> <class>net.nextep.amundsen.security.domain.User</class> <class>net.nextep.amundsen.energy.domain.User</class> <!-- [...] --> <exclude-unlisted-classes>true</exclude-unlisted-classes> <properties> <property name="eclipselink.logging.level" value="INFO" /> <property name="eclipselink.ddl-generation" value="create-tables" /> <property name="eclipselink.ddl-generation.output-mode" value="database" /> <property name="eclipselink.orm.throw.exceptions" value="true" /> </properties> </persistence-unit> </persistence> Index : This one has the most simple persistence.xml with just the Index class (no shared Class). I'm using named @PersistenceUnit annotation like @PersitenceUnit(name = 'securityPU') (for the User bundle). And finally, I'm using EclipseLink as Jpa provider and Spring DM (+ Spring DM Server in the development process) The problem is the following : When the User bundle is deployed, I'm able to persist User objects. When the User bundle and Energy bundles are both deployed, I'm not able to persist User objects (neither the Energy object). But I don't have any exception at all ! There is no problem at all with the Index bundle. The bug is dataSource independent (I tried with PostgreSQL and MySQL so far). My first conclusion was that the <class>net.nextep.amundsen.security.domain.User</class> in both persistence unit was causing the trouble. I tried without it (and hiding the User dependent object in the Energy bundle) but it failed too. I'm a bit confused about that bug. I'm also not quite sure about the transaction management in this context. I wasn't the one who designed this architecture (but I tell my intern OK without testing it.. shame on me) but if I could understand this bug and maybe fix it without rewrite the bundle (and break my intern work), I would appreciate. Am I doing something wrong ? (it's obvious, but what..) Did I miss something while reading documentation ? By the way, I'm also looking for some best practices or advices when it comes to JPA, EclipseLink (or whatever JPA Provider) and Spring DM (and OSGi in general). I found interesting slides from Mike Keith about this topic (by browsing Stackoverflow).

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  • Error when creating a new entity foo, editing a previously existing foo, then saving. Generic 4004 e

    - by Tarks
    The steps are as simple as that so I imagine there's something else going on here, the problem is I just get back 4004, no exception anywhere etc, making it annoying to debug, I get this from the ie error window Microsoft JScript runtime error: Unhandled Error in Silverlight Application Code: 4004 Category: ManagedRuntimeError Message: System.Windows.Ria.DomainOperationException: Submit operation failed. An error occurred while updating the entries. See the inner exception for details. at System.Windows.Ria.OperationBase.Complete(Exception error) at System.Windows.Ria.SubmitOperation.Complete(Exception error) at System.Windows.Ria.DomainContext.CompleteSubmitChanges(IAsyncResult asyncResult) at System.Windows.Ria.DomainContext.<c_DisplayClassd.b_5(Object ) public void TurnPage(bool forward) { TurnPageForward = forward; // If the pages are already turning then don't try and skip days, just run the animation function so it inreases the speed if (!workBook.IsTransitioning && !IsWaitingForData) { IsWaitingForData = true; workBook.SnapshotPages(); NoteCtx.SubmitChanges().Completed += (s, a) => { workBook.ClearPageContents(); CurrentDate = CurrentDate.AddDays(forward ? 1 : -1); PullNotes(CurrentDate); }; } else { workBook.BeginTurnPages(TurnPageForward); } } public void PullNotes(DateTime? noteTime) { NoteCtx.NoteItems.Clear(); var loadOp = NoteCtx.Load(NoteCtx.GetNoteItemsForDayQuery(CurrentDate)); loadOp.Completed += new EventHandler(NotesReady); }

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  • How to clean-up an Entity Framework object context?

    - by Daniel Brückner
    I am adding several entities to an object context. try { forach (var document in documents) { this.Validate(document); // May throw a ValidationException. this.objectContext.AddToDocuments(document); } this.objectContext.SaveChanges(); } catch { // How to clean-up the object context here? throw; } If some of the documents pass the the validation and one fails, all documents that passed the validation remain added to the object context. I have to clean-up the object context because it may be reused and the following can happen. var documentA = new Document { Id = 1, Data = "ValidData" }; var documentB = new Document { Id = 2, Data = "InvalidData" }; var documentC = new Document { Id = 3, Data = "ValidData" }; try { // Adding document B will cause a ValidationException but only // after document A is added to the object context. this.DocumentStore.AddDocuments(new[] { documentA, documentB, documentC }); } catch (ValidationException) { } // Try again without the invalid document B. this.DocumentStore.AddDocuments(new[] { documentA, documentC }); This will again add document A to the object context and in consequence SaveChanges() will throw an exception because of a duplicate primary key. So I have to remove all already added documents in the case of an validation error. I could of course perform the validation first and only add all documents after they have been successfully validated. But sadly this does not solve the whole problem - if SaveChanges() fails all documents still remain add but unsaved. I tried to detach all objects returned by this.objectContext.ObjectStateManager.GetObjectStateEntries(EntityState.Added) but I am getting a exception stating that the object is not attached. So how do I get rid of all added but unsaved objects?

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  • How can i Write list type returning value in Linq with Entity FrameWork?

    - by programmerist
    How can i return List<personel> data type from below procedure. if i press F5 it throw me this error: Error 1 Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.List'. An explicit conversion exists (are you missing a cast?) C:\Documents and Settings\yusufk\Desktop\EFTestSolutions\WebApplicationTest1\WebApplicationTest1\Default.aspx.cs 101 61 WebApplicationTest1 i think that: i should rearrange or recode "select new {. . . . " ? protected List<personel> GetPersonalsData2() { List<personel> personeller; using (FirmaEntities firmactx = new FirmaEntities()) { personeller = (from p in firmactx.Personals select new { p.ID, p.Name, p.SurName }); return personeller.ToList(); } } } public class personel { public int ID { get; set; } public string Name { get; set; } public string SurName { get; set; } }

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  • Entity Framework in n-layered application - Lazy loading vs. Eager loading patterns

    - by Marconline
    Hi all. This questions doesn't let me sleep as it's since one year I'm trying to find a solution but... still nothing happened in my mind. Probably you can help me, because I think this is a very common issue. I've a n-layered application: presentation layer, business logic layer, model layer. Suppose for simplicity that my application contains, in the presentation layer, a form that allows a user to search for a customer. Now the user fills the filters through the UI and clicks a button. Something happens and the request arrives to presentation layer to a method like CustomerSearch(CustomerFilter myFilter). This business logic layer now keeps it simple: creates a query on the model and gets back results. Now the question: how do you face the problem of loading data? I mean business logic layer doesn't know that that particular method will be invoked just by that form. So I think that it doesn't know if the requesting form needs just the Customer objects back or the Customer objects with the linked Order entities. I try to explain better: our form just wants to list Customers searching by surname. It has nothing to do with orders. So the business logic query will be something like: (from c in ctx.CustomerSet where c.Name.Contains(strQry) select c).ToList(); now this is working correctly. Two days later your boss asks you to add a form that let you search for customers like the other and you need to show the total count of orders created by each customer. Now I'd like to reuse that query and add the piece of logic that attach (includes) orders and gets back that. How would you front this request? Here is the best (I think) idea I had since now. I'd like to hear from you: my CustomerSearch method in BLL doesn't create the query directly but passes through private extension methods that compose the ObjectQuery like: private ObjectQuery<Customer> SearchCustomers(this ObjectQuery<Customer> qry, CustomerFilter myFilter) and private ObjectQuery<Customer> IncludeOrders(this ObjectQuery<Customer> qry) but this doesn't convince me as it seems too complex. Thanks, Marco

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  • How to implement a left outer join in the Entity Framework.

    - by user206736
    I have the following SQL query:- select distinct * from dbo.Profiles profiles left join ProfileSettings pSet on pSet.ProfileKey = profiles.ProfileKey left join PlatformIdentities pId on pId.ProfileKey = profiles.Profilekey I need to convert it to a LinqToEntities expression. I have tried the following:- from profiles in _dbContext.ProfileSet let leftOuter = (from pSet in _dbContext.ProfileSettingSet select new { pSet.isInternal }).FirstOrDefault() select new { profiles.ProfileKey, Internal = leftOuter.isInternal, profiles.FirstName, profiles.LastName, profiles.EmailAddress, profiles.DateCreated, profiles.LastLoggedIn, }; The above query works fine because I haven't considered the third table "PlatformIdentities". Single left outer join works with what I have done above. How do I include PlatformIdentities (the 3rd table) ? I basically want to translate the SQL query I specified at the beginning of this post (which gives me exactly what I need) in to LinqToEntities. Thanks

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  • How can i return IEnumarable data from function in GridView with Entity FrameWork?

    - by programmerist
    protected IEnumerable GetPersonalsData() { // List personel; using (FirmaEntities firmactx = new FirmaEntities()) { var personeldata = (from p in firmactx.Personals select new { p.ID, p.Name, p.SurName }); return personeldata.AsEnumerable(); } } i wan to send GetPersonelData() into GridView DataSource. Like That: gwPersonel.DataSource = GetPersonelData(); gwPersonel.DataBind(); it monitored to me on : gwPersonel.DataBind(); this error: "The ObjectContext instance has been disposed and can no longer be used for operations that require a connection."

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  • Entity Framework - in model first, how do I get my EF classes to be based on the existing domain cla

    - by Greg
    Hi, If I already have domain classes, and I want to be able persist them using EF via a model first approach how do I do this? For example do I go to the EF designer (in VS2010) and create the model and generate the classes, then go to these EF classes and somehow manually modify them? But then would there be an issue if I needed to change the model and re-create database TSQL from the model for updates? What's the easiest approach?

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  • Unidirectional One-to-Many Associations in Entity Framework 4?

    - by Eric J.
    Does EF 4 support unidirectional one-to-many associations, as in: public class Parent { public int Id { get; set; } public string Something { get; set; } public List<Child> AllMyChildren { get; set; } } public class Child { public int Id { get; set; } public string Anotherthing { get; set; } // I don't want a back-reference to the Parent! // public int ParentId { get; set; } } When I try to compile my project with an association between Parent and Child where End2 Navigation is blank (because I unchecked the End2 Navigation Property checkbox in the Add Association dialog), I get Error 2027: No mapping specified for the following EntitySet/AssociationSet - Child.

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  • Entity Framework VS LINQ to SQL VS ADO.NET with stored procedures?

    - by BritishDeveloper
    How would you rate each of them in terms of: Performance Speed of development Neat, intuitive, maintainable code Flexibility Overall I like my SQL and so have always been a die-hard fan of ADO.NET and stored procedures but I recently had a play with Linq to SQL and was blown away by how quickly I was writing out my DataAccess layer and have decided to spend some time really understanding either Linq to SQL or EF... or neither? I just want to check, that there isn't a great flaw in any of these technologies that would render my research time useless. E.g. performance is terrible, it's cool for simple apps but can only take you so far

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  • How to get dynamic SQL result from SP in entity framework?

    - by KentZhou
    Suppose I have following SP to run a dynamic sql ALTER PROCEDURE [dbo].[MySP] AS BEGIN declare @sql varchar(4000) select @sql = 'select cnt = count(*) from Mytable ..... '; exec (@sql) END then in edmx, I add the sp and import function for this sp. the return type is scalars int32. then I want to use this function in code like: int? result = context.MySP(); I got error said "cannot implicitly convert type System.Data.Objects.ObjectResults to int?" If use var result = context.MySP(); then Single() cann't be applied to context.MySP(). How to get the result for this case?

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  • Add child to existing parent record in entity framework.

    - by Shawn Mclean
    My relationship between the parent and child is that they are connected by an edge. It is similiar to a directed graph structure. DAL: public void SaveResource(Resource resource) { context.AddToResources(resource); //Should also add children. context.SaveChanges(); } public Resource GetResource(int resourceId) { var resource = (from r in context.Resources .Include("ToEdges").Include("FromEdges") where r.ResourceId == resourceId select r).SingleOrDefault(); return resource; } Service: public void AddChildResource(int parentResourceId, Resource childResource) { Resource parentResource = repository.GetResource(parentResourceId); ResourceEdge inEdge = new ResourceEdge(); inEdge.ToResource = childResource; parentResource.ToEdges.Add(inEdge); repository.SaveResource(parentResource); } Error: An object with the same key already exists in the ObjectStateManager. The existing object is in the Unchanged state. An object can only be added to the ObjectStateManager again if it is in the added state. Image: I have been told this is the sequence in submitting a child to an already existing parent: Get parent - Attach Child to parent - submit parent. That is the sequence I used. The code above is extracted from an ASP.NET MVC 2 application using the repository pattern.

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