CODEWITHSUNDEEP
c#.netautomappernullreferenceexception
MatteS
MatteS

Reputation: 1542

AutoMapper catches and ignores NullReferenceException

Maybe this is by design, but we initially did not expect automapper to catch and ignore all NullReferenceExceptions in our mappings. We mostly use the MapFrom and create sometimes complex expressions. We want these mappings to fail if there's any exception, even a NullReferenceException, but we cant get AutoMapper to do that. Is there any way to make automapper not ignore all these exceptions without having to write a custom value resolver for every case? This would mean alot of extra code for us, so much in fact that it probably would be less code without using automapper in the first place.

These are the test that we would expect to all pass:

[TestFixture]
public class Tests
{
    [SetUp]
    public void Setup() { Mapper.Reset(); }

    [Test]
    public void ShouldThrowMappingExceptionUsingMapFromExpression()
    {
        Mapper.CreateMap<Source, Destination>()
            .ForMember(d => d.DestinationMember, o => o.MapFrom(s => s.SourceMember.SourceProperty))
            ;

        Assert.Throws<AutoMapperMappingException>(() => Mapper.Map<Source, Destination>(new Source()));
    }

    [Test]
    public void ShouldThrowMappingExceptionUsingResolveUsingExpression()
    {
        Mapper.CreateMap<Source, Destination>()
            .ForMember(d => d.DestinationMember, o => o.ResolveUsing(s => s.SourceMember.SourceProperty))
            ;

        Assert.Throws<AutoMapperMappingException>(() => Mapper.Map<Source, Destination>(new Source()));
    }

    [Test]
    public void ShouldThrowMappingExceptionUsingResolverInstance()
    {
        Mapper.CreateMap<Source, Destination>()
            .ForMember(d => d.DestinationMember, o => o.ResolveUsing(new TestValueResolver()).FromMember(s => s.SourceMember))
            ;

        Assert.Throws<AutoMapperMappingException>(() => Mapper.Map<Source, Destination>(new Source()));
    }

    [Test]
    public void ShouldThrowMappingExceptionUsingResolverType()
    {
        Mapper.CreateMap<Source, Destination>()
            .ForMember(d => d.DestinationMember, o => o.ResolveUsing<TestValueResolver>().FromMember(s => s.SourceMember))
            ;

        Assert.Throws<AutoMapperMappingException>(() => Mapper.Map<Source, Destination>(new Source()));
    }

}

public class Destination
{
    public string DestinationMember { get; set; }
}

public class Source
{
    public SourceChild SourceMember { get; set; }
}

public class SourceChild
{
    public string SourceProperty { get; set; }
}

public class TestValueResolver : ValueResolver<SourceChild, string>
{
    protected override string ResolveCore(SourceChild source)
    {
        return source.SourceProperty;
    }
}

Upvotes: 2

Views: 3009

Answers (1)

Danny Tuppeny
Danny Tuppeny

Reputation: 42423

This behaviour has now been changed in AutoMapper! :-)

https://github.com/AutoMapper/AutoMapper/issues/122

Upvotes: 2

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