Question

I can’t seem to figure out how to compare boolean values in a C# lambda expression for EF4. I’ve tried:

cl.Where(c => c.Received == false);

and this:

cl.Where(c => !c.Received);

and this:

cl.Where(c => c.Received.Equals(false));

but I keep getting this error:

Exception Details: System.NotSupportedException: Unable to create a constant value
of type 'System.Object'. Only primitive types ('such as Int32, String, and Guid')
are supported in this context.

After spending a good amount of time researching this I’m still missing something. I’m fairly new to Lambdas so pointers would be appreciated.

Edit2: more code re:comment

int bar = 42;
var cl = db.foo.Where(c => c.baz.Equals(bar));
//codez (just an if statement)
cl.Where(c => c.Received == false).OrderByDescending(c => c.dateAdded);

That’s it. Even if I remove the orderby it still doesn’t work

Edit3:

Solution:

int bar = 42;
var cl = db.foo.Where(c => c.baz == bar);
cl.Where(c => c.Received == false).OrderByDescending(c => c.dateAdded);

Answer 1

The issue is most likely in the c.baz.Equals(bar) line. If you change it to

var cl = db.foo.Where(c => c.baz.Equals(bar)).ToList();

you should see the exception thrown on that line, because you force evaluation of the IQueryable<T>.

Instead of comparing objects, you should compare their IDs, like this:

(edited to reflect the conversation in the comments and changes to the OP)

var cl = db.foo.Where(c => c.baz == bar.id);