Entity Framework 6 Code First function mapping

Question

I want integrate Entity Framework 6 to our system, but have problem.

1. I want to use Code First. I don’t want to use Database First *.edmx file for other reasons

Answer 1

now Entity Framework is not beta, so maybe you solved your problem, but this one solved my problem How to use scalar-valued function with linq to entity?

Answer 2

Haven't tried this yet, but Entity Framework 6.1 includes public mapping API. Moozzyk has implemented Store Functions for EntityFramework CodeFirst using this new functionality.

Here's what the code looks like:

public class MyContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Add(new FunctionsConvention<MyContext>("dbo"));
    }

    [DbFunction("MyContext", "CustomersByZipCode")]
    public IQueryable<Customer> CustomersByZipCode(string zipCode)
    {
        var zipCodeParameter = zipCode != null ?
            new ObjectParameter("ZipCode", zipCode) :
            new ObjectParameter("ZipCode", typeof(string));

        return ((IObjectContextAdapter)this).ObjectContext
            .CreateQuery<Customer>(
                string.Format("[{0}].{1}", GetType().Name, 
                    "[CustomersByZipCode](@ZipCode)"), zipCodeParameter);
    }

    public ObjectResult<Customer> GetCustomersByName(string name)
    {
        var nameParameter = name != null ?
            new ObjectParameter("Name", name) :
            new ObjectParameter("Name", typeof(string));

        return ((IObjectContextAdapter)this).ObjectContext.
            ExecuteFunction("GetCustomersByName", nameParameter);
    }
}

Answer 3

You can get the Store type from the primitive type with a helper method:

    public static EdmType GetStorePrimitiveType(DbModel model, PrimitiveTypeKind typeKind)
    {
        return model.ProviderManifest.GetStoreType(TypeUsage.CreateDefaultTypeUsage(
            PrimitiveType.GetEdmPrimitiveType(typeKind))).EdmType;
    }

In your example, you'd have to change the return parameter's type:

var edmType = GetStorePrimitiveType(model, PrimitiveTypeKind.String);

I found the help I needed here: http://entityframework.codeplex.com/discussions/466706

Answer 4

Here are all the steps needed [Tested] :

Install-Package EntityFramework.CodeFirstStoreFunctions

Declare a class for output result:

public class MyCustomObject
{
   [Key]
   public int Id { get; set; }
   public int Rank { get; set; }
}

Create a method in your DbContext class

[DbFunction("MyContextType", "SearchSomething")]
public virtual IQueryable<MyCustomObject> SearchSomething(string keywords)
{
   var keywordsParam = new ObjectParameter("keywords", typeof(string)) 
                           { 
                              Value = keywords 
                            };
    return (this as IObjectContextAdapter).ObjectContext
    .CreateQuery<MyCustomObject>(
     "MyContextType.SearchSomething(@keywords)", keywordsParam);
}

Add

public DbSet<MyCustomObject> SearchResults { get; set; }

to your DbContext class

Add in the overriden OnModelCreating method:

modelBuilder.Conventions
.Add(new CodeFirstStoreFunctions.FunctionsConvention<MyContextType>("dbo"));

And now you can call/join with a table values function like this:

CREATE FUNCTION SearchSomething
(   
    @keywords nvarchar(4000)
)
RETURNS TABLE 
AS
RETURN 
(SELECT KEY_TBL.RANK AS Rank, Id
FROM MyTable 
LEFT JOIN freetexttable(MyTable , ([MyColumn1],[MyColumn2]), @keywords) AS KEY_TBL      
ON MyTable.Id = KEY_TBL.[KEY]  
WHERE KEY_TBL.RANK > 0   
)
GO