Entity Framework 6 - Knowledge Base (KB)
123 results in tag: dbcontext
How to fix the datetime2 out-of-range conversion error using DbContext and SetInitializer?
I'm using the DbContext and Code First APIs introduced with Entity Framework 4.1....The ...data model... uses basic data types such as ...string... and ...DateTime.... The only data annotation I'm using in some cases is ...[Required]..., but that's not on...
asked by Alex Angas
How do I foreach through my dbcontext entities in EF 4.1?
I'm using ASP.NET Entity Framework 4.1 MVC 3 (C#)...I want to foreach through all the entities in my DbContext. I need to be able to dynamically refer to my entities in order to make dynamic views....I have read Lerman's book, two MVC (2 & 3) books, msdn,...
asked by Benjamin
Entity Framework, Code First, Update "one to many" relationship with independent associations
It took me way too long to find a solution to the scenario described below. What should seemingly be a simple affair proved to be rather difficult. The question is: ...Using Entity Framework 4.1 (Code First approach) and "Independent associations" how do ...
asked by Martin
Entity Framework - How to implement a Repository, using a custom DbContext?
We are starting to develop a small framework in our company, to share code between different applications. For data access we are using EF4. We have a custom DbContext class and a generic Repository:...public class RMDbContext : DbContext { // .... } ...
asked by Rui Jarimba
DbContext SaveChanges() - Detecting updated entities
I have overridden the SaveChanges() method in the Entity Framework 4.1 DbContext class....My override looks like this:...public override int SaveChanges() { IEnumerable<DbEntityEntry> modifiedEntityEntries = ChangeTracker.Entries().Where( e => e.Stat...
asked by FantasticJamieBurns
C# EF 4.1 Create table dynamically within DbContext
I want to add tables to a SQLCe database at runtime, since the tablenames are not static and known at compile time. I try to do this with Entity Framework 4.1 and DbContext as follows:...public class PersonContext : DbContext { public PersonContext() ...
asked by Juergen
ExecuteStoreQuery with Dbcontext
I want to use ...ExecuteStoreQuery... function of Entity Framework and I was wondered that my context variable didn't have ...ExecuteStoreQuery... method....So, I discovered that it's a method of ...ObjectContext... class, but I've already used ...DbConte...
asked by Chuck Norris
Why does Entity Framework automatically use the ObjectContext instead of the DbContext when mapping database tables using ADO.NET Entity datamodel
I am following the database approach first; I have created the tables in my SQL Server 2008 database, then I map those tables to Entity Framework classes using an ADO.NET Entity Data Model. But when I opened the designer.cs file I found the following code...
asked by john Gu
'ObjectContext' vs 'DbContext' in Entity Framework
I'm using the ...DbContext... class within code that I am creating that is based on the Generic Repositories and Unit of Work design patterns. (I am following the guidance ...here....) While working on this project I have encountered the ...ObjectContext....
asked by afr0
Entity Framework Code-First: "The ObjectStateManager cannot track multiple objects with the same key."
I'm running into an issue with Entity Framework code-first in MVC3. I'm hitting this exception:...An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key....This is a...
asked by Josh
DbContext is very slow when adding and deleting
When using DbContext in a database-first scenario I found out that adding and deleting entities is very slow compared to ObjectContext. If adding 2000 entities and saving the changes at the end, DbContext is 3 to 5 times slower than ObjectContext (btw.: I...
asked by Jürgen Bayer
The provider did not return a ProviderManifestToken string error
I am trying to create a web app using ASP.Net MVC3, Entity Framework and MySQL....I have added the following code to my Web.Config file....<connectionStrings> <add name="ContactContext" connectionString="server=localhost;database=contacts;uid=root;pwd...
asked by har
One DbContext per web request... why?
I have been reading a lot of articles explaining how to set up Entity Framework's ...DbContext... so that only one is created and used per HTTP web request using various DI frameworks....Why is this a good idea in the first place? What advantages do you g...
asked by Andrew
Entity Framework DbContext Connection string in app.config/web.config not being seen
So, I have followed this instruction from ADO.NET team blog to try to make a small test project. I have double-checked everything. It doesn't seem to work and keeps saying connection string is missing....http://blogs.msdn.com/b/adonet/archive/2011/03/15/e...
asked by Tom
dbcontext loading related entities using select(), include() and where() not working
I have the following relationship between the entities. Company 1 ---* Appointments *---1 Employee...I have the .net asp membership in a separate database. Whenever a user is created it can be assigned to companies, employees, or administrators roles....i...
asked by Thupten
DbSet.Find method ridiculously slow compared to .SingleOrDefault on ID
I have the following code (Database is SQL Server Compact 4.0):...Dim competitor=context.Competitors.Find(id) ...When I profile this the Find method takes 300+ms to retrieve the competitor from a table of just 60 records....When I change the code to:...Di...
asked by Dabblernl
Multithreading Entity Framework: The connection was not closed. The connection's current state is connecting
So I have a windows service process that performs a workflow process. The back end uses Repository and UnitofWork Pattern and Unity on top of Entity Framework with the entities class generated from the edmx. I won't go into a whole lot of detail as its no...
asked by Brandon
Why is EF code first throwing model backing context exception? Using 4.0.3
Heres the exception:...The model backing the 'ScannerContext' context has changed since the database was created. Consider using Code First Migrations to update the database (...http://go.microsoft.com/fwlink/?LinkId=238269...)....I get this every...
asked by jwrightmail
Manage the lifetime of dbContext
I would like to tie the lifetime of a dbContext to the lifetime of a session, to - for example - be able to commit or abandon changes on a group of mutations on the dbcontext over multiple requests....Are there any other (better?) ways to accomplish this?...
asked by Martijn
How do I stop Entity Framework from generating BOTH ObjectContext and dbContext
Background...Visual Studio 2012...NEW Model.EDMX file created in VS2012...Copied some of the EDMX xml from a previously created EDMX into the new one...Problem / Question...Now. The EDMX (TT transform, custom tool, whatever, etc.) is generating BOTH DbCo...
asked by Jay Stevens
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