Retrieve an object from entityframework without ONE field

Question

I\'m using entity framework to connect with the database. I\'ve one little problem:

I\'ve one table which have one varbinary(MAX) column(with filestream).

I\

Answer 1

I'd like to share my attempts to workaround this problem in case somebody else is in the same situation.

I started with what Jeremy Danyow suggested, which to me is the less painful option.

// You need to include all fields in the query, just make null the ones you don't want.
var results = context.Database.SqlQuery("SELECT Field1, Field2, Field3, HugeField4 = NULL, Field5 FROM TableName");

In my case, I needed a IQueryable<> result object so I added AsQueryable() at the end. This of course let me add calls to .Where, .Take, and the other commands we all know, and they worked fine. But there's a caveat:

The normal code (basically context.myEntity.AsQueryable()) returned a System.Data.Entity.DbSet, while this approach returned System.Linq.EnumerableQuery.

Apparently this means that my custom query gets executed "as is" as soon as needed and the filtering I added later is done afterwards and not in the database.

Therefore I tried to mimic Entity Framework's object by using the exact query EF creates, even with those [Extent1] aliases, but it didn't work. When analyzing the resulting object, its query ended like

FROM [dbo].[TableName] AS [Extent1].Where(c => ...

instead of the expected

FROM [dbo].[TableName] AS [Extent1] WHERE ([Extent1]...

Anyway, this works, and as long as the table is not huge, this method will be fast enough. Otherwise you have no option than to manually add the conditions by concatenating strings, like classic dynamic SQL. A very basic example in case you don't know what I'm talking about:

string query = "SELECT Field1, Field2, Field3, HugeField4 = NULL, Field5 FROM TableName";
if (parameterId.HasValue)
    query += " WHERE Field1 = " + parameterId.Value.ToString();
var results = context.Database.SqlQuery(query);

In case your method sometimes needs this field, you can add a bool parameter and then do something like this:

IQueryable results;
if (excludeBigData)
    results = context.Database.SqlQuery("SELECT Field1, Field2, Field3, HugeField4 = NULL, Field5 FROM TableName").AsQueryable();
else
    results = context.myEntity.AsQueryable();

If anyone manages to make the Linq extensions work properly like if it was the original EF object, please comment so I can update the answer.