Using AutoMapper to map unknown types

Question

I'm using AutoMapper to copy the properties of one object to another: This is my code:

// Get type and create first object
Type itemType = Type.GetType(itemTypeName);
var item = Activator.CreateInstance(itemType);

// Set item properties
.. Code removed for clarity ..

// Get item from Entity Framework DbContext
var set = dataContext.Set(itemType);
var itemInDatabase = set.Find(id);
if (itemInDatabase == null)
{
    itemInDatabase = Activator.CreateInstance(itemType);
    set.Add(itemInDatabase);
}

// Copy item to itemInDatabase
Mapper.CreateMap(itemType, itemType);
Mapper.Map(item, itemInDatabase);

// Save changes
dataContext.SaveChanges();

The problem is that Mapper.Map() throws an AutoMapperMappingException:

Missing type map configuration or unsupported mapping.

Mapping types:
Object -> MachineDataModel
System.Object -> MyProject.DataModels.MachineDataModel

Destination path:
MachineDataModel

Source value:
MyProject.DataModels.MachineDataModel

I don't really understand what the problem is, and what can I do to fix it?

Daniel Hilgarth · Accepted Answer · 2013-02-18 15:28:00Z

17

You need to use the non-generic overload of Map:

Mapper.Map(item, itemInDatabase, item.GetType(), itemInDatabase.GetType());

The reason is that the generic version you are currently using doesn't use the runtime type of the instances you pass. Rather it uses the compile time type - and the compile time type of item is object because that's the return value of Activator.CreateInstance.

answered Feb 18, 2013 at 15:28

Daniel Hilgarth

175k41 gold badges346 silver badges450 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Joel Over a year ago

Haha, I was gonna tell you to switch the order of the parameters, but you were too fast. But it works like a charm! I'll accept your answer as soon as I can.

Daniel Hilgarth Over a year ago

@Joel: Yeah, I first wrote down the relevant parts and then looked up the correct ordering :)

Collectives™ on Stack Overflow

Using AutoMapper to map unknown types

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related