np (NullPropagation) throws NullReferenceException with methods

[NetMage]

If I have something like
np(Element(@0).Value)
or
np(qList.FirstOrDefault(Tag = "NAME").Value)

I get a NullReferenceException in ExpressionParser.GenerateConditional in /Parser/ExpressionParser.cs line 1207.

It works if I manually expand np to == null ? : null - is there a limitation to what np understands?

[StefH]

For now it can only work on properties. (Updated the info on https://github.com/StefH/System.Linq.Dynamic.Core/wiki/NullPropagation)

I'll take a look if it can be updated for methods...

[StefH]

@NetMage

Please try MyGet preview version : System.Linq.Dynamic.Core.1.0.19-ci-11874

[NetMage]

I am attempting to add the feed to LINQPad and test. I see v1.0.18 in MyGet and 1.0.19 in Nuget. Either one seems to give me the same error.

[StefH]

Did you try that exact version?

[StefH]

It should work.

See https://github.com/StefH/System.Linq.Dynamic.Core/pull/309/files#diff-26864b997e03a24c9676bd97c489ac76R1308

[StefH]

@NetMage Did you have time to test?

[StefH]

@NetMage Can you please verify ?

[StefH]

@NetMage can you please test if this version does fix your issue?

[NetMage]

So I figured out how to get it in LINQPad and tried it. Instead of a null reference exception I now get a ParseException:

The 'np' (null-propagation) function requires the first argument to be a MemberExpression

Is that what should happen?

[StefH]

Can you provide a full working example?

Because when I run these tests"https://github.com/StefH/System.Linq.Dynamic.Core/pull/309/files#diff-26864b997e03a24c9676bd97c489ac76R1308

It works as expected.

[NetMage]

When I execute the following in LINQPad, or in a VS2019 Console Program using ci-12228 installed, I get a Null Reference Exception on the Select:

    void Main() {
        var defaultRoleName = "x";
        var users = new[] { new User { Roles = new List<Role>() } }.AsQueryable();
    
        // Act
        var resultDynamic = users.Select("np(Roles.FirstOrDefault(false).Name, @0)", defaultRoleName).ToDynamicArray();
        resultDynamic.Dump();
    }
    
    // Define other methods, classes and namespaces here
    public interface IEntity {
        long Id { get; set; }
    }
    
    public abstract class Entity : IEntity {
        public long Id { get; set; }
    }
    
    public class User : Entity {
        public string IdentityName { get; set; }
        public string DisplayName { get; set; }
        public string EmailAddress { get; set; }
        public ICollection<Role> Roles { get; set; }
    
        public bool HasRole(string role) {
            return Roles.Any(r => r.Name == role);
        }
    }
    
    public class Role : Entity {
        public string Name { get; set; }
        public string Description { get; set; }
        public ICollection<User> Users { get; set; }
    }

[StefH]

Please try version System.Linq.Dynamic.Core.1.0.20-ci-12230, that one works for me:

[NetMage]

It is working with ci-12230. Note I am getting an error with the latest, ci-12237, Index out of range exception.

[StefH]

Ok. Thanks for testing.

Note that I have several branches running in parallel, that's the reason a later version can be a different/older branch.

[StefH]

#309