CODEWITHSUNDEEP
linqentity-frameworklinq-to-entities
tschmit007
tschmit007

Reputation: 7800

EF dynamic query with enum

I'm trying to build a dynamic query whit a condition on an emum

enumField & enumValue == enumValue

for this, during the analysis the following is called

Expression GenerateBitWiseAnd(Expression left, Expression right) {
    return Expression.And(left, right);
}

this throws an exception

And binary operator is not defined for `EnumType` and `EnumType`.

The equality operator runs well

Expression GenerateEqual(Expression left, Expression right) {
    return Expression.Equal(left, right);
}

But I can't figure how to handle a [Flags] without the And bits operator.

The question is: from here how to dynamically forge my query to check my enum.

My application is targeting .Net 4

Upvotes: 2

Views: 415

Answers (1)

Richard Deeming
Richard Deeming

Reputation: 31198

You'll need to convert the Enum to its underlying type before you can operate on it:

Expression GenerateBitWiseAnd(Expression left, Expression right) 
{
   if (left.Type.IsEnum)
   {
      var enumType = left.Type;
      var compareType = Enum.GetUnderlyingType(enumType);
      var enumField = Expression.Convert(left, compareType);
      var enumValue = Expression.Convert(right, compareType);
      var and = Expression.And(enumField, enumValue);
      return Expression.Convert(and, enumType);
   }

   return Expression.And(left, right);
}

Upvotes: 1

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