Operator '&&' cannot be applied to operands of type 'bool' and 'bool?' [duplicate]

Answer 1

You can try like this.

 foreach (var user in dataContext.Users
          .Where(u => roles.Contains(u.RoleID.Value) 
             && (u.isValid ?? false))) // note the bracket around (u.isValid ?? false)

Or

foreach (var user in dataContext.Users
       .Where(u => roles.Contains(u.RoleID.Value) 
        && (u.isValid.HasValue && u.isValid))) //you can use HasValue to check for null

Answer 2

You have to wrap it in parentheses:

roles.Contains(u.RoleID.Value) && (u.isValid ?? false)

bit of confused with (u.isValid ?? false), does this not mean that if u.isValid == null then make it false and look for users where u.isValid is false, this is not what I want.

No, it just means that nulls are treated as false and that all users are taken which isValid is neither null nor false. It works because the ??-operator converts the Nullable<bool> to a bool, so you can use it with &&. I don't like it, i prefer explicit code that i understand later:

roles.Contains(u.RoleID.Value) && u.isValid.HasValue && u.isValid.Value

or simpler by using the ==-operator with the bool?:

roles.Contains(u.RoleID.Value) && u.isValid == true

Answer 3

Given bool will default to false anyway you could use GetValueOrDefault

roles.Contains(u.RoleID.Value) && u.isValid.GetValueOrDefault()

Note - GetValueOrDefault does not appear to be supported by EF - see ticket