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  • Entity Framework Model with inheritance and RIA Services

    - by TimothyP
    Hi, We have an entity framework model with has some inheritance in it. The following example is not the actuall model, but just to make my point... Let's say Base class: Person Child classes: Employee, Customer The database has been generated, the DomainService has been created and we can get to the data: lstCustomers.ItemsSource = context.Persons; EntityQuery<Person> query = context.GetPeopleQuery().Take(4); context.Load(query); But how can I modify the query to only return Customers ?

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  • Changing database structure at runtime with Entity Framework?

    - by Teddy
    Hi. I have to write a solution that uses different databases with different structure from the same code. So, when a user logs to the application I determine to which database he/she is connected to at runtime. The user can create tables and columns at any time and they have to see the change on the fly. The reason that I use one and the same code the information is manipulates the same way for the different databases. How can I accomplish this at runtime? Actually is the Entity Framework a good solution for my problem? Thanks in advance.

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  • Entity Framework - Using a lookup (picklist) table with a lookup key

    - by Dave
    I'm working on a WPF application that is working well using the Entity Framework (3.5 SP1) for complicated table structures. The problem now is I want to get a list from the EF that includes lookups into a picklist table that has multiple picklists in it. In SQL I would write a sub select as such: SELECT Name, (Select typeName from PickLists where type_id = items.type_id and picklist_key=333) as Type_desc FROM Items There are no Foreign keys for this, and the picklists table is never updated using the EF, so it is read only as far as the EF is concerned. I'm not sure the best method to put this into the model if at all. I'm displaying in a read-only datagrid on a dashboard. Thanks!

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  • implement N-Tier Entity Framework 4.0 with DTOs

    - by kathy
    Hi, I'm currently building a web based system and trying to implement N-Tier Entity Framework 4.0 with DTOs in a SOA Architecture. I am having a problem understanding how I should implement the Data Access Layer (DAL) , the Business Logic Layer (BLL) and the Presentation Layer. Let’s suppose that I have a “useraccount” entity has the following : Id FirstName LastName AuditFields_InsertDate AuditFields_UpdateDate In the DAL I created a class “UserAccountsData.cs” as the following : using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace OrderSystemDAL { public static class UserAccountsData { public static int Insert(string firstName, string lastName, DateTime insertDate) { using (OrderSystemEntities db = new OrderSystemEntities()) { return Insert(db, firstName, lastName, insertDate); } } public static int Insert(OrderSystemEntities db, string firstName, string lastName, DateTime insertDate) { return db.UserAccounts_Insert(firstName, lastName, insertDate, insertDate).ElementAt(0).Value; } public static void Update(int id, string firstName, string lastName, DateTime updateDate) { using (OrderSystemEntities db = new OrderSystemEntities()) { Update(db, id, firstName, lastName, updateDate); } } public static void Update(OrderSystemEntities db, int id, string firstName, string lastName, DateTime updateDate) { db.UserAccounts_Update(id, firstName, lastName, updateDate); } public static void Delete(int id) { using (OrderSystemEntities db = new OrderSystemEntities()) { Delete(db, id); } } public static void Delete(OrderSystemEntities db, int id) { db.UserAccounts_Delete(id); } public static UserAccount SelectById(int id) { using (OrderSystemEntities db = new OrderSystemEntities()) { return SelectById(db, id); } } public static UserAccount SelectById(OrderSystemEntities db, int id) { return db.UserAccounts_SelectById(id).ElementAtOrDefault(0); } public static List<UserAccount> SelectAll() { using (OrderSystemEntities db = new OrderSystemEntities()) { return SelectAll(db); } } public static List<UserAccount> SelectAll(OrderSystemEntities db) { return db.UserAccounts_SelectAll().ToList(); } } } And in the BLL I created a class “UserAccountEO.cs” as the following : using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Collections; using OrderSystemDAL; namespace OrderSystemBLL { public class UserAccountEO { public int Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public DateTime InsertDate { get; set; } public DateTime UpdateDate { get; set; } public string FullName { get { return LastName + ", " + FirstName; } } public bool Save(ref ArrayList validationErrors) { ValidateSave(ref validationErrors); if (validationErrors.Count == 0) { if (Id == 0) { Id = UserAccountsData.Insert(FirstName, LastName, DateTime.Now); } else { UserAccountsData.Update(Id, FirstName, LastName, DateTime.Now); } return true; } else { return false; } } private void ValidateSave(ref ArrayList validationErrors) { if (FirstName.Trim() == "") { validationErrors.Add("The First Name is required."); } if (LastName.Trim() == "") { validationErrors.Add("The Last Name is required."); } } public void Delete(ref ArrayList validationErrors) { ValidateDelete(ref validationErrors); if (validationErrors.Count == 0) { UserAccountsData.Delete(Id); } } private void ValidateDelete(ref ArrayList validationErrors) { //Check for referential integrity. } public bool Select(int id) { UserAccount userAccount = UserAccountsData.SelectById(id); if (userAccount != null) { MapData(userAccount); return true; } else { return false; } } internal void MapData(UserAccount userAccount) { Id = userAccount.Id; FirstName = userAccount.FristName; LastName = userAccount.LastName; InsertDate = userAccount.AuditFields_InsertDate; UpdateDate = userAccount.AuditFields_UpdateDate; } public static List<UserAccountEO> SelectAll() { List<UserAccountEO> userAccounts = new List<UserAccountEO>(); List<UserAccount> userAccountDTOs = UserAccountsData.SelectAll(); foreach (UserAccount userAccountDTO in userAccountDTOs) { UserAccountEO userAccountEO = new UserAccountEO(); userAccountEO.MapData(userAccountDTO); userAccounts.Add(userAccountEO); } return userAccounts; } } } And in the PL I created a webpage as the following : using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.UI; using System.Web.UI.WebControls; using OrderSystemBLL; using System.Collections; namespace OrderSystemUI { public partial class Users : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { LoadUserDropDownList(); } } private void LoadUserDropDownList() { ddlUsers.DataSource = UserAccountEO.SelectAll(); ddlUsers.DataTextField = "FullName"; ddlUsers.DataValueField = "Id"; ddlUsers.DataBind(); } } } Is the above way the right way to Implement the DTOs pattern in n-tier Architecture using EF4 ??? I would appreciate your help Thanks.

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  • LINQ to SQL vs Entity Framework for an app with a future SQL Azure version

    - by Craig L
    I've got a vertical market Dot Net Framework 1.1 C#/WinForms/SQL Server 2000 application. Currently it uses ADO.Net and Microsoft's SQLHelper for CRUD operations. I've successfully converted it to Dot Net Framework 4 C#/WinForms/ SQL Server 2008. What I'd like to do is also offer my customers the ability to use SQL Azure as a backend storage for their data instead of local/LAN SQL Server. If I know SQL Azure is in my application's future, should I: A. Switch to LINQ to SQL B. Swith to Entity Framework C. Stick with ADO.Net and SQLHelper Thanks !

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  • Entity framework and many to many queries unusable?

    - by John Landheer
    I'm trying EF out and I do a lot of filtering based on many to many relationships. For instance I have persons, locations and a personlocation table to link the two. I also have a role and personrole table. EDIT: Tables: Person (personid, name) Personlocation (personid, locationid) Location (locationid, description) Personrole (personid, roleid) Role (roleid, description) EF will give me persons, roles and location entities. EDIT: Since EF will NOT generate the personlocation and personrole entity types, they cannot be used in the query. How do I create a query to give me all the persons of a given location with a given role? In SQL the query would be select p.* from persons as p join personlocations as pl on p.personid=pl.personid join locations as l on pl.locationid=l.locationid join personroles as pr on p.personid=pr.personid join roles as r on pr.roleid=r.roleid where r.description='Student' and l.description='Amsterdam' I've looked, but I can't seem to find a simple solution.

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  • !(ReferenceEquals()) vs != in Entity Framework 4

    - by Eric J.
    Unless a class specifically overrides the behavior defined for Object, ReferenceEquals and == do the same thing... compare references. In property setters, I have commonly used the pattern private MyType myProperty; public MyType MyProperty { set { if (myProperty != value) { myProperty = value; // Do stuff like NotifyPropertyChanged } } } However, in code generated by Entity Framework, the if statement is replaced by if (!ReferenceEquals(myProperty, value)) Using ReferenceEquals is more explicit (as I guess not all C# programmers know that == does the same thing if not overridden). Is there any difference that's escaping me between the two if-variants? Are they perhaps accounting for the possibility that POCO designers may have overridden ==? In short, if I have not overridden ==, am I save using != instead of ReferencEquals()?

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  • Entity Framework and the XmlIgnoreAttribute

    - by Mikey Cee
    Say you have a one to one relationship in your entity model. The code generator will decorate it with the following attributes: [global::System.Xml.Serialization.XmlIgnoreAttribute()] [global::System.Xml.Serialization.SoapIgnoreAttribute()] public RelatedObject Relationship { get {...} set {...} } I want to serialize my parent object together with all its properties for which data has been loaded through an XML web service. Obviously, these related properties do not get serialized because of these attributes. So for my purposes I just want to remove these "don't serialize me" attributes. I can do a find and replace in the designer code, but any modifications I make in the designer will put these attributes back in. How do I permanently get rid of these attributes? VS 2008 / EF 3.5.

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  • Changing an extention method from linq-to-sql to entity framework

    - by Jova
    I'm changing my project from working with Linq-to-SQL to working with Entity Framework. I have some extention methods that extend the classes created by LINQ and I'm wondering how to change them to work with the entities instead Here's an example. public static int GetPublishedArticlesCount(this Table<Article> source) { return GetPublishedArticles(source.Context as DataContext, null).Count(); } This method gets the number of published articles. Instead of using this Table<Article>, what should I use instead?

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  • Entity Framework 5 vs Telerik OpenAccess ORM (specifically)

    - by dimoss
    I am starting a new project and want advice on choosing an ORM. I know this topic has been brought up before, but this topic is specific to either Entity Framework 5 (not 4) or Telerik OpenAccess ORM. The project will reside on Windows Azure and use Windows Azure SQL Database. I will migrate it to .NET 4.5 once 4.5 is live on Azure. I am currently a Telerik Ultimate Collection subscriber. Does anyone in the know have any pros/cons for this scenario? I am slightly leaning towards Telerik OpenAccess at the moment. Thanks

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  • Entity Framework Performance Inconsistency Compared to Sql Management Studio

    - by AndyV
    I'm getting timeouts with a very basic EF statement. I'm simply doing a select from a single table with a Entity.Title.StartsWith("test") and a .Take(25). When I run this for a search that returns no results I get a timeout. If I profile and grab the sql statement it looks fine, and if I run that sql in Management Studio it runs in a fraction of a second! Why would the same query run sub-second in Management Studio and timeout when generated by EF and called from an Asp.Net app?

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  • EF Code First - Include(x => x.Properties.Entity) a 1 : Many association

    - by VulgarBinary
    Given a EF-Code First CTP5 entity layout like: public class Person { ... } which has a collection of: public class Address { ... } which has a single association of: public class Mailbox { ... } I want to do: PersonQuery.Include(x => x.Addresses).Include("Addresses.Mailbox") WITHOUT using a magic string. I want to do it using a lambda expression. I am aware what I typed above will compile and will bring back all Persons matching the search criteria with their addresses and each addresses' mailbox eager loaded, but it's in a string which irritates me. How do I do it without a string? Thanks Stack!

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  • Entity framework error: The conversion of a datetime2 data type to a datetime data

    - by EdenMachine
    I know there are a ton of posts about this issue but none of them seem to solve my problem. Here's the scenario: I have a CreateDate DateTime column in my MS SQL Server database User table that is non-nullable and is automatically set using GetDate() method in "Default Value or Binding" setting. I am able to create a User just fine with the standard EF Insert but when I try to update the user, I get this error: The conversion of a datetime2 data type to a datetime data type resulted in an out-of-range value. What is the trick to not having the EF worry about the CreateDate column for updates? I have the StoreGenerationPattern = Identity but that isn't helping. Here are the EF properties for my Entity Property: http://screencast.com/t/8ndQRn9N And here is my Update method: http://screencast.com/t/UXIzhkhR

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  • EF problem with entity re-ordering and uniqueness constraint

    - by wpfwannabe
    I am using Entity Framework and I've come to an interesting stumbling block. Let's say there is a db table "Item" with "sequence" column of type int (and others of course). Column "sequence" must be unique and it is used for (re)ordering of items. EF maps this table to "Item" class with "sequence" int property. Now let's say I want to swap position of two items by mutually exchanging each other's sequence number. Upon calling SaveChanges() EF throws an exception complaining about "sequence" uniqueness. It probably generates two UPDATEs and the first one probably fails. I assume that plain SQL solution to this issue is using a third UPDATE to introduce a unique sequence value in the process but I am stuck with EF. Any thoughts?

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  • Entity Framework does not display the last change from the database

    - by Jack
    Entity Framework does not display the last change from the database, but after sometime it show the updated content. I don't any special change on the server or on the page. Thank in advance. Jack Here is the code i use to get the list: var m = from r in ett.Article_Relations from i in ett.Article_Articles from a in ett.Article_Contents where r.MenuItemID == id && r.Article_Articles.ArticleID == i.ArticleID && a.LanguageID == LanguageID && i.ArticleID == a.Article_Articles.ArticleID select new ArticleViewModel { ArticleID = i.ArticleID, IsActive = i.IsActive, Author = i.ArticleAuthor, Content = a, DateCreated = i.DateCreated };

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  • Stored Procedure in Entity Framework

    - by kamal
    Hi I had added the Stored procedure in my Entity framework and i also imported the functions in the edmx. Is it must to add all the three functions insert, update, and delete functions to a table. I had tried with insert alone and also with all, but why can't i get the name of the stored procedure in the connection string. Let me know what i done clearly. I had added the sp i had imported the functions in the model browser. i had also mapped the insert, update and delete function to the table with return type only for insert and update. Still i can't get the name of SP in the connection string. Please let me know how could i resolve this issue. Thanks in Advance, Kamal.

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  • Entity Framework doesn't like 0..1 to * relationships.

    - by Orion Adrian
    I have a database framework where I have two tables. The first table has a single column that is an identity and primary key. The second table contains two columns. One is a nvarchar primary key and the other is a nullable foreign key to the first table. On the default import of the database I get the following error: Condition cannot be specified for Column member 'ForeignKeyId' because it is marked with a 'Computed' or 'Identity' StoreGeneratedPattern. where ForeignKeyId is the second foreign key reference in the second table. Is this just something the entity model doesn't do? Or am I missing something?

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  • Advanced Where Statements in Linq to Entity Framework

    - by JimJams
    Hi, I am wanting to create a Where statement within my Linq statement, but have hit a bit of a stumbling block. I would like to split a string value, and then search using each array item in the Where clause. In my normal Sql statement I would simply loop through the string array, and build up there Where clause then either pass this to a stored procedure, or just execute the sql string. But am not sure how to do this with Linq to Entity? ( From o In db.TableName Where o.Field LIKE Stringvalue Select o ).ToList() Hope you can help. Thanks in advance!

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  • Entity Framework with File-Based Database

    - by Dave Swersky
    I am in the process of developing a desktop application that needs a database. The application is currently targeted to SQL Express 2005 and works wonderfully. However, I'm not crazy about having this dependency on SQL Express and would prefer to use a small file-based database. My problem is that I am using Entity Framework. I have tried both SQL Compact and SQLite, and they both have bizarre problems with EF v1. I get errors creating the Model, invalid models when it does get created... it's a nightmare. I'm about ready to give up and write a data layer and repository in the good-old-school Connection/Command pattern. Not my favorite plan... Is there a lightweight, file-based database out there that plays well with EF? OR Is there a better ORM tool that I should use instead of EF with my lightweight DB?

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  • where should I put the EF entity and data annotations in asp.net mvc + entity framework project

    - by giddy
    So I have a DataEntity class generated by EntityFramework4 for my sqlexpress08 database. This data context is exposed via a WCF Data Service/Odata to silverlight and win forms clients. Should the data entities + edmx file (generated by EF4) go in a separate class library? The problem here then is I would specify data annotations for a few entities and then some of them would require specific MVC attributes (like CompareAttribute) so the class library would also reference mvc dlls. There also happen to be entity users which will be encapsulated or wrapped into an IIdentity in the website. So its pretty tied to the mvc website. Or Should it maybe go in a Base folder in the mvc project itself? Mostly the website is data driven around the database, like approve users, change global settings etc. The real business happens in the silverlight and win forms apps. Im using mvc3 rc2 with Razor. Thanks

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  • Automapping to EntityKeys in Entity Framework

    - by CodeGrue
    Does anyone have a technique to automap (using Automapper) references to child entities. So say I have a ViewModel: class AddressModel { int Id; string Street; StateModel State; } class StateModel { int Id; string Name; } And I pass this into a repository to map to equivalent entities in Entity Framework. When Automapping, I want it to automap AddressModel.State.ID to the EntityKey of AddressEntity.StateReference. So hand crafted code would look like this: addressEntity.Id = AddressModel.Id; addressEntity.Street = AddressModel.Street addressEntity.StateReference.EntityKey = new EntityKey("MyDB.States", "Id", AddressModel.State.Id); Obviously, when automapper tries to assign an Address.State.Id to the equivalent in EF, an exception is thrown.

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  • Call function in query in Entity framework 3.5

    - by Ashwani K
    Hello All: I am trying to run following query in entity framework 3.5 var test = from e in customers where IsValid(e) select e; Here IsValid function takes current customer and validate against some conditions and returns false or true. But when I am trying to run the query it is giving error "LINQ Method cannot be translated into a store expression." Can any body tell me any other approach? One approach I can think of is to write all validation conditions here, but that will make the code difficult to read. Thanks Ashwani

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  • Using entity framework to detect changes in related table and action appropriate inserts and deletes

    - by Kohan
    Lets say i have a Person table, a Role table with a trel table PersonRoles linking them as many to many. I create a new person and assign them to 2 roles (role 1, role 3). I then want to edit this person; so i retrieve their data and bind their roles to a checkboxes. I change the values (Deselect role 1 and select role 2 instead) I then post this data back through a viewmodel. Can i then get Entity Framework to update these roles for me, as in delete the entry in PersonRoles to role 1 and then add a new entry as role 2? Or do i have to do the logic for this myself? Cheers, Kohan

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  • Entity Framework 4: C# !(ReferenceEquals()) vs !=

    - by Eric J.
    Unless a class specifically overrides the behavior defined for Object, ReferenceEquals and == do the same thing... compare references. In property setters, I have commonly used the pattern private MyType myProperty; public MyType MyProperty { set { if (myProperty != value) { myProperty = value; // Do stuff like NotifyPropertyChanged } } } However, in code generated by Entity Framework, the if statement is replaced by if (!ReferenceEquals(myProperty, value)) Using ReferenceEquals is more explicit (as I guess not all C# programmers know that == does the same thing if not overridden). Is there any difference that's escaping me between the two if-variants? Are they perhaps accounting for the possibility that POCO designers may have overridden ==? In short, if I have not overridden ==, am I save using != instead of ReferencEquals()?

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  • Problem calling stored procedure with a fixed length binary parameter using Entity Framework

    - by Dave
    I have a problem calling stored procedures with a fixed length binary parameter using Entity Framework. The stored procedure ends up being called with 8000 bytes of data no matter what size byte array I use to call the function import. To give some example, this is the code I am using. byte[] cookie = new byte[32]; byte[] data = new byte[2]; entities.Insert("param1", "param2", cookie, data); The parameters are nvarchar(50), nvarchar(50), binary(32), varbinary(2000) When I run the code through SQL profiler, I get this result. exec [dbo].[Insert] @param1=N'param1',@param2=N'param2',@cookie=0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 [SNIP because of 16000 zeros] ,@data=0x0000 All parameters went through ok other than the binary(32) cookie. The varbinary(2000) seemed to work fine and the correct length was maintained. Is there a way to prevent the extra data being sent to SQL server? This seems like a big waste of network resource.

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