Automapper complex object mapping NullReference exception

Asked May 06 '14 at 14:46

Active May 07 '14 at 13:57

Viewed 657 times

I have the following classes

public class Group 
{
    public int Id { get; set; }
    public string Name { get; set; }

    public virtual ICollection<GroupTier> Tiers { get; set; }
}

public class GroupTier : IEntity
{
    public int Id { get; set; }
    public int GroupId { get; set; }
    public int Tier { get; set; }
    public decimal Amount { get; set; }

    public virtual Group Group { get; set; }
}

I am trying to map to the following ViewModel

public class GroupViewModel 
{
    public int Id { get; set; }
    public string Name { get; set; }
    public IEnumerable<decimal> Tiers { get; set; }
}

using the configuration

configuration.CreateMap<Group, GroupViewModel>()
   .ForMember(m => m.Tiers, opt => opt.MapFrom(u => u.Tiers.OrderBy(q => q.Tier).Select(q => q.Amount)));

I am using EF6 to query from the database. I am having trouble when the Group.Tiers is null. How can I handle the null value?

When I use the this configuration

configuration.CreateMap<Group, GroupViewModel>()
    .ForMember(m => m.Tiers, opt => opt.MapFrom(u => u.Tiers == null ? new List<decimal>() : u.Tiers.OrderBy(q => q.Tier).Select(q => q.Amount)));

I am getting this error

Cannot compare elements of type 'System.Collections.Generic.ICollection'

edited May 07 '14 at 13:57

asked May 06 '14 at 14:46

Saanch

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Try use [link](http://automapper.org/) – Daniel Melo May 06 '14 at 14:48
what do you mean by use link? – Saanch May 06 '14 at 14:49
You may want to try this question/answer: http://stackoverflow.com/questions/11555721/automapper-map-if-not-null-otherwise-custom-convert – Chris L May 06 '14 at 14:56
@Saanch you clicked on link? it's a framework to map your objects to objects(AutoMaper) – Daniel Melo May 06 '14 at 17:39
What version of AutoMapper are you using? And are you using the LINQ projection? – Jimmy Bogard May 06 '14 at 17:47
Why not just initialize `Tiers` as an empty collection (e.g. HashSet) in `Group`'s constructor? That's a pretty common approach. – Gert Arnold May 06 '14 at 21:07
@JimmyBogard I am using `Projection` to fetch the data. – Saanch May 07 '14 at 01:23
@DanielMelo I know what is `AutoMapper` @Jimmy Bogard is the author of this framework. Read my question properly before polluting the comment section with unconstructive comments. – Saanch May 07 '14 at 01:25
@JimmyBogard I am using version `3.2.1` – Saanch May 07 '14 at 02:26
@Saanch, sorry dude I thought you were using another form of mapping. I noticed that the object names are incorrect. Can not be? (GroupModel to GroupViewModel) – Daniel Melo May 07 '14 at 13:17
@DanielMelo ggod catch :) – Saanch May 07 '14 at 13:41
What is the `Tier` type that you reference in your `OrderBy` on the `Tiers` property of the group? You didn't include it in your question and i think that the problem lives here – samy May 07 '14 at 13:54
@samy Check the `GroupTier` class `Tier` is an `int` field – Saanch May 07 '14 at 13:57
Indeed, i must have missed it while copy/pasting the problem – samy May 07 '14 at 14:06
I cannot replicate the error using the code you posted (albeit i remove the EF IEntity interface). Could you post the whole stack trace of the error? – samy May 07 '14 at 14:15

Automapper complex object mapping NullReference exception

0 Answers0