entity-framework - w3toppers.com

Forcing code-first to always initialize a non-existent database?

Initializer is executed when you need to access the database so if you want to create database on app start use anything of the following: context.Database.Initialize(true); //If set to true the initializer is run even if it has already been run. context.Database.Create() http://msdn.microsoft.com/en-us/library/system.data.entity.database.initialize(v=vs.103).aspx CreateDatabaseIfNotExists An implementation of IDatabaseInitializer that will recreate and optionally re-seed the … Read more

Why does the entity framework need an ICollection for lazy loading?

I think i found the solution…See here for more details: http://social.msdn.microsoft.com/Forums/en-US/adodotnetentityframework/thread/47296641-0426-49c2-b048-bf890c6d6af2/ Essentially you want to make the ICollection type protected and use this as the backing collection for the public IEnumerable public class Product { // This is a mapped property protected virtual ICollection<Photo> _photos { get; set; } // This is an un-mapped property … Read more

Entity framework code first delete with cascade

You mentioned EF code first which means EF 4.1 but you have shown example of deleting object in EF 4. Correct approach to delete object in EF 4.1 without loading it from database is: var category = new Category() { CategoryId = 1 }; context.Categories.Attach(category); context.Categories.Remove(category); context.SaveChanges(); If you didn’t change anything in configuration of … Read more

Can anyone spot why I keep getting this error testing the EF 5 beta

Looks like you are using the EF5 EntityFramework.dll but then running with .NET 4 installed instead of .NET 4.5. If you are intending to target .NET 4.5, then make sure that .NET 4.5 is installed on the machine on which you are running the code. VS11 installs .NET 4.5 for you, but you can also … Read more

Entity framework 4.3 run migrations at application start

The best way should be using new MigrateDatabaseToLatestVersion initializer. Database.SetInitializer<YourContext>( new MigrateDatabaseToLatestVersion<YourContext, YourMigrationsConfig>()); Database.Initialize(false);

Entity Framework select one of each group by date

If you want to get the whole Posts. You can try this: var query = Posts.GroupBy(p => p.Type) .Select(g => g.OrderByDescending(p => p.Date) .FirstOrDefault() )

Why Entity Framework performs faster than Dapper in direct select statement [closed]

ORM (Object Relational Mapper) is a tool that creates layer between your application and data source and returns you the relational objects instead of (in terms of c# that you are using) ADO.NET objects. This is basic thing that every ORM does. To do this, ORMs generally execute the query and map the returned DataReader … Read more

How to use interface properties with CodeFirst

An imperfect solution is to just merge these interfaces you want to persist into base classes and break down the underlying objects with subclasses. EF does support this, and if you go with Table Per Hierarchy (the default), you can sort all of the underlying subclassed objects by a shared property using a regular LINQ … Read more

Why can’t Entity Framework see my Stored Procedure’s column information?

Try adding this line to the beginning of your stored procedure: SET FMTONLY OFF You can remove this after you have finished importing.

How can set a default value constraint with Entity Framework 6 Code First?

Unfortunately the answer right now is ‘No’. But you can vote for Better support for default values EDIT 30 Mar 2015: It’s coming in EF7… Support database default values in Code First EDIT 30 Jan 2017: General support for default database values is part of EF Core (the new name for EF7)… Default values EDIT … Read more