C# Linq: Combine multiple .Where() with an *OR* clause

Question

I have been searching a lot about my current problem but I could not find a real answer to solve that issue.

I am trying to build a LINQ Query that produces the followi

Answer 1

You can use Expression to create in one step like this:

Expression> exp = (model => 
                                    ((model.Field1.HasValue && c.Field1 == X) &&
                                    (model.Field2.HasValue && c.Field2 == X)) ||
                                     model.Field3 == X
                                    )

Once you have your predicates defined, it's very easy to use them in a query.

var result = Query.AsQueryable().Where(exp)

Check the code in this gist: my gist url

UPDATE 1: If You have to use steps to create your expression you can use this:

Expression> exp = c => true;
if (model.Field1.HasValue) 
{
    var prefix = exp.Compile();
    exp = c => prefix(c) && c.Field1 == X;
}

if (model.Field2.HasValue) 
{
    var prefix = exp.Compile();
    exp = c => prefix(c) && c.Field2 == X;
}

[...] like 20 more of these .Where() calls.