What is Automapper?

Shivprasad koirala

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28 Apr 2015CPOL2 min read

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This post explains the need of Automapper in C# and MVC projects.

What is Automapper ?

Automapper is a simple reusable component which helps you to copy data from object type to other. If you wish to get automapper, read this.

For example, below is a simple employee class loaded with some dummy data.

class Employee 
{
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public decimal Salary { get; set; }
}
// Loaded with some data
Employee emp = new Employee();
emp.FirstName = "Shiv";
emp.LastName = "Koirala";
emp.Salary = 100;

Now let’s say we want to load the above employee data into a “Person” class object.

class Person
{
        public string FirstName { get; set; }
        public string LastName { get; set; }
}

So normally, developers end up writing mapping code as shown in the below snippet.

Person per = new Person();
per.FirstName = emp.FirstName;
per.LastName = emp.LastName;

At first glance, this does not look much of a problem but wait…think, what if you want to use this mapping code again and again.

So as a best practice, you would like to centralize this mapping code and reuse this mapping code again and again. This is where our super hero “AutoMapper” comes to the rescue. “Automapper” sits in between both the objects like a bridge and maps the property data of both objects.

Using Automapper is a two-step process:

Create the Map.
Use the Map so that objects can communicate.

Mapper.CreateMap<Employee, Person>(); // Create Map
Person per =  Mapper.Map<Employee, Person>(emp); // Use the map

I have not specified mapping. How does it work?

In the above example property names of both classes are same so the mapping happens automatically.

How can we map different property names in Automapper?

If the classes have different property names, then we need to use “ForMember” function to specify the mapping.

Mapper.CreateMap<Employee, Person>()
.ForMember(dest => dest.FName , opt => opt.MapFrom(src => src.FirstName))
.ForMember(dest => dest.LName , opt => opt.MapFrom(src => src.LastName));