Linqpad & EF5 Code First

Question

Getting the following error when trying to run a query against a dbcontext assembly in Linqpad.

InvalidOperationException: The model backing the 'UserQuery' context has changed since the database was created. Consider using Code First Migrations to update the database (http://go.microsoft.com/fwlink/?LinkId=238269).

Having done a bit of reading it seems that:

Database.SetInitializer<DiaryAssistantContext>(null);

is needed. However this is already in my derived DbContext class.

Can anybody give me a pointer?

score 10 · Answer 1 · answered Aug 30 '12 at 05:01

10

LINQPad subclasses your typed data context so you can run queries without referencing the instance. Maybe the SetInitializer method needs the subclassed type.

What happens if you replace this code:

Database.SetInitializer<DiaryAssistantContext>(null);

with this:

typeof (Database).GetMethod ("SetInitializer").MakeGenericMethod (GetType()).Invoke (null, new object[] { null });

?

answered Aug 30 '12 at 05:01

Joe Albahari

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I have added your suggested line to the constructor of the dbcontext derived class and it works perfectly. I'm not sure fully understand why though. – dandcg Aug 30 '12 at 09:49
1

GetType() is virtual, so it's equivalent to calling Database.SetInitializer(null); when run in LINQPad – Joe Albahari Aug 31 '12 at 01:37

score 6 · Accepted Answer · answered Feb 19 '13 at 19:56

While an answer has already been accepted, in my case I wanted a solution that was a little more compile-time friendly. The following solution is similar to the example in the accepted answer that uses reflection, but will provide a little extra compile-time checking:

Expression<Action> setInitializerExpression = () => Database.SetInitializer<MyContext>(null);
var setInitializerCall = (MethodCallExpression) setInitializerExpression.Body;
var setInitializerMethodInfo =
    setInitializerCall.Method.GetGenericMethodDefinition().MakeGenericMethod(GetType());
setInitializerMethodInfo.Invoke(null, new object[] {null});

Linqpad & EF5 Code First

2 Answers2