NestedMappings don't work properly when nested type is Array(or Collection)


Nested mappings are not taken into consideration when they are arrays or collections.
See attached modified your unit test.

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Closed Sep 2, 2011 at 11:47 PM by jbogard
All issues moved to GitHub https://github.com/AutoMapper/AutoMapper/issues


BPierzchlewicz wrote Jul 23, 2009 at 9:27 AM

The problem appears only when source maping type equals destination type.
As you can see in attached test, I used:
var dest = Mapper.Map<OuterSource, OuterSource>(source);

This behavior is due to condition in class EnumerableMapperBase:

if (context.DestinationType.IsAssignableFrom(context.SourceType) && context.SourceValue != null)
return context.SourceValue;

jbogard wrote Aug 16, 2009 at 1:47 AM

I'm not sure I understand the failing test - you're mapping something to itself, so it just returns the object. Do you have one that highlights the collection issue?

BPierzchlewicz wrote Aug 17, 2009 at 7:34 AM

Yes, I am mapping object with the same source and destination type.
OuterSource.InnerArray is an array, and despite of I ignore some fields (Mapper.CreateMap<InnerSource, InnerDest>().ForMember(a => a.IgnoreValue, act => act.Ignore());)
in result set I get InnerArray with all fields.
Maybe I should write:
Mapper.CreateMap<InnerSource, InnerSource>().ForMember(a => a.IgnoreValue, act => act.Ignore());

DomiH wrote Oct 8, 2009 at 11:27 AM


We had a similar problem (see attached class diagram). I initialized the Mapper as followed:

//Client -> Proxy
Mapper.CreateMap<IndexDocument, Proxy.IndexDocument>();
Mapper.CreateMap<IndexField, Proxy.IndexField>();
Mapper.CreateMap<TextField, Proxy.TextField>();
Mapper.CreateMap<BinaryField, Proxy.BinaryField>();
Mapping from IndexDocument to Proxy.IndexDocument:
var proxy = Mapper.Map<IndexDocument, Proxy.IndexDocument>(document);

My IndexDocument contains 3 TextFields. Therefore my Proxy-IndexDocument should contain 3 Proxy.TextFields as well – but it doesn’t. Instead 3 Proxy.IndexFields have been created. I think the problem lies in the Map Method of EnumerableMapperBase<TEnumerable>:

//Do not use the Generic Type of the IEnumerable, because it could be a base type or interface.
// Instead use the type of the item when iterating over the enumerable.
//Type sourceElementType = TypeHelper.GetElementType(context.SourceType, sourceValue);
Type destElementType = TypeHelper.GetElementType(context.DestinationType);

In the foreach for enumerableValue I retrieve Source- and Destination-Type as follows:

//Use the concret type of the list item
var sourcType = item.GetType();
//Retrieve destination type from mapper
var destinationType = (from m in mapper.ConfigurationProvider.GetAllTypeMaps()
                             where m.SourceType.Equals(sourcType)
                             select m.DestinationType).FirstOrDefault();
I know that is not optimal to retrieve the mapped destination-type for each source-type. There should be a kind of caching. I did not find a way to retrieve the destination-type by only specifying the source-type. I think that would be nice, too. E.g.:

var destinationType = mapper.ConfigurationProvider.FindDestinationType(Type sourceType)
// or
var sourceType = mapper.ConfigurationProvider.FindSourceType(Type destinationType)

Best regards,