Use automapper to update an Entity Framework Entity

Question

I am trying to use Entity Framework and have Automapper update my entity from my contract.

My code looks like this:

var temp = OrderContract;
Order order = dataAccess.FindOne<Order>(x => x.OrderId == temp.OrderId) 
              ?? new Order();

Mapper.Map(OrderContract, order);

if (order.OrderId <= 0)
   dataAccess.Add(order);

(Note: I am using the Repository Pattern. dataAccess.FindOne calls CreateQuery to return one entity.)

The problem I am having is with the relationships. I get this error when I do an update (inserts work just fine):

The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value. If the foreign-key does not support null values, a new relationship must be defined, the foreign-key property must be assigned another non-null value, or the unrelated object must be deleted.

I am guessing that automapper is not updating the way I want it to. From the error message and googling around I have surmised that my relationships that are collections (and maybe even the ones that are not collections) are being recreated by Automapper.

How can I tell Automapper to just update and not remake any objects or collections?

Guesses:

I read that maybe I need to use the UseDestinationValue option for automapper. I went back and put that on all my collections But when I do that then my inserts fail with a foreign key violation.

Code Mappings:

Using UseDestinationValue only on one collection (this one inserts but will not update):

//+ Source
Mapper.CreateMap<SourceContract, Source>()
    .IgnoreAllNonExisting();

//+ SelectedRequirement
Mapper.CreateMap<SelectedRequirementContract, SelectedRequirement>()
    .ForMember(x => x.SelectedRequirementId, opt => opt.MapFrom(src => src.RequirementId))
    .IgnoreAllNonExisting();

//+ Comment Contract
Mapper.CreateMap<CommentContract, Comment>()
    .ForMember(x => x.CommentText, opt => opt.MapFrom(src => src.Comment))
    .IgnoreAllNonExisting();

//+ Order Automapper setup
Mapper.CreateMap<OrderContract, Order>()
    .ForMember(x => x.Source, opt => opt.MapFrom(src => src.Source))
    .ForMember(x => x.Comment, opt => opt.MapFrom(src => src.Comment))
    //Although a mapping was created for Comment entity,
    //we still need to map the CommentId of the Order entity otherwise it will remain null during an update.
    //Another way to handle this would be to Delete CommentId from the Order entity.
    //However, if anyone updates (Update from model) OrderDataModel.edmx that property would show up again thus causing
    //a null value to be inserted during an update.
    .ForMember(x => x.CommentId, opt => opt.MapFrom(src => src.Comment.CommentId))
    .ForMember(x => x.SelectedRequirements, opt => {opt.UseDestinationValue(); opt.MapFrom(src => src.Requirements);})
    .ForMember(x => x.OrderStateId, opt => opt.MapFrom(src => src.StateId))
    .ForMember(x => x.OrderStateId, opt => opt.MapFrom(src => src.StateId))
    .IgnoreAllNonExisting();

Using UseDestinationValue everywhere (this one does not insert):

//+ Source
Mapper.CreateMap<SourceContract, Source>()
    .IgnoreAllNonExisting();

//+ SelectedRequirement
Mapper.CreateMap<SelectedRequirementContract, SelectedRequirement>()
    .ForMember(x => x.SelectedRequirementId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.RequirementId); })
    .IgnoreAllNonExisting();

//+ Comment Contract
Mapper.CreateMap<CommentContract, Comment>()
    .ForMember(x => x.CommentText, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment); })
    .IgnoreAllNonExisting();

//+ Order Automapper setup
Mapper.CreateMap<OrderContract, Order>()
    .ForMember(x => x.Source, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Source); })
    .ForMember(x => x.Comment, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment); })
    //Although a mapping was created for Comment entity,
    //we still need to map the CommentId of the Order entity otherwise it will remain null during an update.
    //Another way to handle this would be to Delete CommentId from the Order entity.
    //However, if anyone updates (Update from model) OrderDataModel.edmx that property would show up again thus causing
    //a null value to be inserted during an update.
    .ForMember(x => x.CommentId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment.CommentId); })
    .ForMember(x => x.SelectedRequirements, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Requirements); })
    .ForMember(x => x.OrderStateId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.StateId); })
    .ForMember(x => x.OrderStateId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.StateId); })
    .IgnoreAllNonExisting();

What do I need to so I can insert and update?

@shuniar - my contract can be seen here: raw.github.com/gist/1296415/…. The Order class is an entity object and is very large. I would rather not make it presentable unless there is a clear reason how it would be helpful. — Vaccano
AutoMapper does not merge, it creates new. If you want to merge, then don't use AutoMapper and write your own a -> b mapping method. — O.O
@O.O - AutoMapper can do both. Mapper.Map(sourceObject, destObject) — Vaccano

np-hard np-hard · Accepted Answer · 2011-11-15T20:02:58

I think what you want is for AutoMapper to not create your EF entity and take the one you sent it. In version2.0 of auto mapper there is an overload to map method where you can basically pass your datacontext delegate and let EF create your object.

Please look at this article.

Use automapper to update an Entity Framework Entity

1 Answers