LINQ to Entities does not recognize the method 'System.String ToString()' method, and this method cannot be translated into a store expression

Question

I\'m migrating some stuff from one mysql server to a sql server but i can\'t figure out how to make this code work:

using (var context = new Context())
{
            


        

Answer 1

As others have answered, this breaks because .ToString fails to translate to relevant SQL on the way into the database.

However, Microsoft provides the SqlFunctions class that is a collection of methods that can be used in situations like this.

For this case, what you are looking for here is SqlFunctions.StringConvert:

from p in context.pages
where  p.Serial == SqlFunctions.StringConvert((double)item.Key.Id)
select p;

Good when the solution with temporary variables is not desirable for whatever reasons.

Similar to SqlFunctions you also have the EntityFunctions (with EF6 obsoleted by DbFunctions) that provides a different set of functions that also are data source agnostic (not limited to e.g. SQL).