Unmapped field on destination is set to null

Question

I am using Automapper for mapping two objects.

I have field VehicleModel in the destination which has some default value. I don't have a mapping for this destination field in the source. So I didn't map it. After mapping is done, my default value is set to null value on the destination. The data objects looks like below.

public partial class Source
{

private Car[] cars;

public Car[] Cars
{
    get { return this.cars; }
    set { this.cars = value; }
}
}

public partial class Destination
{
private OutputData output;

public OutputData Output
{            
    get {  return this.output; }
    set {  this.output= value; }
}   
}

public class OutputData
{
private List<Cars> cars;
private string vehicleModel;

public Car[] Cars
{
    get { return this.cars; }
    set { this.cars = value; }
}
public string VehicleModel
{            
    get {  return this.vehicleModel; }
    set {  this.vehicleModel= value; }
}
}

Mapping between Source and OutputData.

Mapper.CreateMap<Source, OutputData>();
Mapper.CreateMap<Source, Destination>().ForMember( dest => dest.Output, input => 
    input.MapFrom(s=>Mapper.Map<Source, OutputData>(s)));

How to avoid this behavior.

Thanks in advance. Sandeep

It would help to see your CreateMap and your class definitions. However, are you providing your destination object when you call Mapper.Map? — PatrickSteele, Jul 26 '12 at 12:33
Please refer to my earlier post for data model http://stackoverflow.com/questions/11633021/automapper-expression-must-resolve-to-top-level-member public class OutputData { private List cars; private string vehicleModel; public Car[] Cars { get{ return this.cars; } set { this.cars = value; } } public String VehicleModel{ get { return this.vehicleModel; } set { this.vehicleModel = value; } } } VehicleModel field has some value before mapping. It doesn't have mapping field in source. After mapping the VehicleModel is set to Null — Sandeep Reddy Pinniti, Jul 26 '12 at 14:03
Please add the code to the question so its readable and others who may be able to help don't have to sift through comments. — PatrickSteele, Jul 26 '12 at 14:30
I have updated the question with the code, please take a look at it. — Sandeep Reddy Pinniti, Jul 27 '12 at 07:12

score 1 · Answer 1 · answered Jul 27 '12 at 23:55

I have modified the code to make it compilable. Correct if something is wrong.

public class Car
{
    public string Brand {get;set;}
}

public partial class Source
{
    private Car[] cars;

    public Car[] Cars
    {
        get { return this.cars; }
        set { this.cars = value; }
    }
}

public partial class Destination
{
    private OutputData output;

    public OutputData Output
    {            
        get {  return this.output; }
        set {  this.output= value; }
    }   
}

public class OutputData
{
    private List<Car> cars;
    private string vehicleModel = "DEFAULTMODEL";

    public Car[] Cars
    {
        get { return cars.ToArray(); }
        set { this.cars = value.ToList(); }
    }
    public string VehicleModel
    {            
        get {  return this.vehicleModel; }
        set {  this.vehicleModel= value; }
    }
}

Note: I added default model.

With you configuration and above code the following mapping works as you expected:

var res = Mapper.Map<Source, Destination>(new Source { Cars = new Car[]{ new Car{ Brand = "BMW" }}});

So looks like you some important piece of code is not provided.

Unmapped field on destination is set to null

1 Answers1