This is the information from the expired link in this answer: https://stackoverflow.com/a/8923063/2005596
When using AutoMapper (http://automapper.codeplex.com ) I often have a scenario where I need to map several entities into one entity. Commonly this occurs when mapping from a number domain entities into a single view model (ASP.NET MVC). Unfortunately the AutoMapper API does not expose functionality to map several entities into one entity; however it is relatively simple to create some helper method to do this. Below I will illustrate the approach that I have taken.
In this example I have the following entities in my domain model
public class Person
{
public int Id { get; set; }
public string Firstname { get; set; }
public string Surname { get; set; }
}
public class Address
{
public int Id { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string Country { get; set; }
}
public class Comment
{
public string Text { get; set; }
public DateTime Created { get; set; }
}
In addition to this I have a requirement to render the person details the person’s address and any related comment on a single page (using ASP.NET MVC). To implement this I have created the view model shown below, which includes data from all three of the domain entities shown above
public class PersonViewModel
{
public int Id { get; set; }
[DisplayName("Firstname")]
public string Firstname { get; set; }
[DisplayName("Surname")]
public string Surname { get; set; }
[DisplayName("Address Line 1")]
public string AddressLine1 { get; set; }
[DisplayName("Address Line 2")]
public string AddressLine2 { get; set; }
[DisplayName("Country Of Residence")]
public string Country { get; set; }
[DisplayName("Admin Comment")]
public string Comment { get; set; }
}
In the controller action method I make three separate calls into the domain layer to retrieve the required entities but this still leaves the issue that I need to map several source entities onto a single destination entity. To perform this mapping I created a helper class which encapsulates AutoMapper and exposes functionality which enables the mapping of several source objects onto one destination object. This class is shown below
public static class EntityMapper
{
public static T Map<T>(params object[] sources) where T : class
{
if (!sources.Any())
{
return default(T);
}
var initialSource = sources[0];
var mappingResult = Map<T>(initialSource);
// Now map the remaining source objects
if (sources.Count() > 1)
{
Map(mappingResult, sources.Skip(1).ToArray());
}
return mappingResult;
}
private static void Map(object destination, params object[] sources)
{
if (!sources.Any())
{
return;
}
var destinationType = destination.GetType();
foreach (var source in sources)
{
var sourceType = source.GetType();
Mapper.Map(source, destination, sourceType, destinationType);
}
}
private static T Map<T>(object source) where T : class
{
var destinationType = typeof(T);
var sourceType = source.GetType();
var mappingResult = Mapper.Map(source, sourceType, destinationType);
return mappingResult as T;
}
}
To map several source objects onto one destination I have made use of the functionality provided by AutoMapper which allows you to perform a mapping between a source object and a destination object that already exists.
Finally below is the code from the controller that retrieves the three entities and performs the mapping onto a single view model
public ActionResult Index()
{
// Retrieve the person, address and comment entities and
// map them on to a person view model entity
var personId = 23;
var person = _personTasks.GetPerson(personId);
var address = _personTasks.GetAddress(personId);
var comment = _personTasks.GetComment(personId);
var personViewModel = EntityMapper.Map<PersonViewModel>(person, address, comment);
return this.View(personViewModel);
}
