Skip to main content

AutoMapper In Asp.Net Core Applications

AutoMapper:

Automapper is an object-to-object mapper. Object to object mapping works by transforming an input object of one type into an output object of a different type. Manually mapping one object property value to another object property value leads to more lines of code, so all this dirty work can be avoided by using the Automapper. As long as all properties names are the same for 2 different objects that need to map, almost zero configuration is needed to map them. 

When To Use AutoMapper?:

In any kind of architecture, it is always advised to not expose the 'Entity'(Table classes) directly. So we will create replica classes for 'Entity' we called them as 'DTO'(Data Transfer Object) or 'VM'(View Models). So this is the real-time best case to use Automapper for mapping 'Entity'(Table classes) data to DTO or VM's.

Create A Sample Dotnet5 Web API Project:

In this demo, we are going to understand the different mapping techniques that are provided by AutoMapper. So here I'm using Web API to accomplish my demo, but I'm not going to show all the API set up from the scratch, so I'm hoping everyone has a good idea on Web API. Here I'm going to show all the logic with and without auto mapper.

Install AutoMapper NuGet:

Package Manager:
Install-Package AutoMapper.Extensions.Microsoft.DependencyInjection -Version 8.1.1

.NET CLI:
dotnet add package AutoMapper.Extensions.Microsoft.DependencyInjection --version 8.1.1

Initial AutoMapper Setup For Asp.Net Core Application:

In Automapper we have to register our source and destination objects in our application. So the best way to organize them is to create a 'Profile'. So we can create a class that inherits 'Profile' and inside of the constructor, we can register our configuration. We can have multiple profiler classes if we need them. So let's create a folder like 'MapperProfiles' and a class like 'AppProfile.cs'
MapperProfiles/AppProfiles.cs:
using AutoMapper;
namespace AutoMapDemo.API.MapperProfiles
{
    public class AppProfile:Profile
    {
        public AppProfile()
        {
            
        }
    }
}
Now we have to register all the 'Profiles' classes we created. Either we register each individual 'Profile' class or we can register a root class like 'Startup.cs' then the library can load all the 'Profile' classes within that namespace.
Startup.cs:
services.AddAutoMapper(typeof(Startup))
Now inject 'AutoMapper.IMapper' interface in the required controller to use the AutoMapper.
Controllers/TestController.cs:
using AutoMapper;
namespace AutoMapDemo.API.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class TestController : ControllerBase
    {
        public TestController(IMapper mapper)
        {
            _mapper = mapper;
        }
    }
}

Simple Object Mapping:

Let's explore the simple object mapping case using Automapper. Now here will try to map object likes
'Entities/Gadgets.cs' and 'Dto/GadgetsDto.cs'.

Entites/Gadgets.cs:
namespace AutoMapDemo.API.Data.Entities
{
    public class Gadgets
    {
        public int Id { get; set; }
        public string ProductName { get; set; }
        public string Brand { get; set; }
        public decimal Cost { get; set; }
        public string Type { get; set; }
    }
}
DTOs/GadgetsDto.cs: 
namespace AutoMapDemo.API.DTOs
{
    public class GadgetsDto
    {
        public int Id { get; set; }
        public string ProductName { get; set; }
        public string Brand { get; set; }
        public decimal Cost { get; set; }
        public string Type { get; set; }
    }
}
Let's go through the code how it looks without a mapper. 
[HttpGet]
[Route("first-gadget")]
public IActionResult GetFirstGadget()
{
	var result = _myWorldDbContext.Gadgets
		.Select(_ => new GadgetsDto { 
			Brand = _.Brand,
			Cost = _.Cost,
			Id = _.Id,
			ProductName = _.ProductName,
			Type = _.Type
		}).FirstOrDefault();
	return Ok(result);
}
  • Here we can observe properties from 'Gadgets.cs' manually assigned to properties from 'GadgetsDto.cs'.
Now let's configure the mapping between objects like 'Gadgets.cs'(Source Object), 'GadgetsDto.cs'(Destination Object) in the 'Profile'.
MapperProfiles/AppProfile.cs:
public class AppProfile:Profile
{
	public AppProfile()
	{
		CreateMap<Gadgets, GadgetsDto>();
	}
}
  • Here left-hand side type is the source object type(Gadgets) and the right-hand side type is the destination object type(GadgetsDto).
Now let's check the code that uses Automapper. 
[HttpGet]
[Route("first-gadget-with-map")]
public IActionResult GetFirstGadgetWithMapping()
{
	var gadgets = _myWorldDbContext.Gadgets.FirstOrDefault();
	var result = _mapper.Map<Gadgets, GadgetsDto>(gadgets);
	return Ok(result);
}
  • Here '_mapper.Map<S, D>()' method to copy the data from the source object to the destination object.

Collection Mapping:

Now let's explore the object collection mapping using AutoMapper. Here we will try to map objects like a collection of 'Gadgets.cs' and the collection of 'GadgetsDto.cs'.

So coming to the configuration in 'Profile', since we have already mapped 'Gadgets' and 'GadgetsDto' for the simple single object mapping in the previous section, so the same configuration will be used by IMapper for the collection as well.

Now, let's look over the code without AutoMapper implementation.
[HttpGet]
[Route("all-gadgets")]
public IActionResult GetAllGadgets()
{
	var gadgets = _myWorldDbContext.Gadgets.ToList();
	List<GadgetsDto> result = new List<GadgetsDto>();
	foreach (var item in gadgets)
	{
		result.Add(new GadgetsDto
		{
			Brand = item.Brand,
			Cost = item.Cost,
			Id = item.Id,
			ProductName = item.ProductName,
			Type = item.Type
		});

	}
	return Ok(result);
}
  • Here looping the data from the database and then assigning data to the 'DTO' object each property manually.
Now, let's look over the code using AutoMapper for the object collection. 
[HttpGet]
[Route("all-gadgets-with-mapper")]
public IActionResult GetAllGadgetsWithMapper()
{
	var gadgets = _myWorldDbContext.Gadgets.ToList();
	List<GadgetsDto> result = _mapper.Map<List<Gadgets>, List<GadgetsDto>>(gadgets);
	return Ok(result);
}
  • (Line: 6) Here '_mapper.Map<List<SourceObject>, List<DestinationObject>>()' method source and destination method should be wrapped around the 'List'. 

Nested Object Mapping:

Let's explore mapping between the objects that contain navigation property(nested objects). Here our source object is like 'Person.cs' which will have navigation property of type 'PersonAddress.cs' and the destination object is like 'PersonDto.cs' which will have navigation property of type 'PersonAddressDto.cs'.

Entities/Person.cs And Entities/PersonAddress.cs:
public class Persons
{
	public int ID { get; set; }
	public string LastName { get; set; }
	public string FirstName { get; set; }
	public int Age { get; set; }
	public List<PersonAddress> PersonAddresses { get; set; }
}

public class PersonAddress
{
	public int PersonAddressId { get; set; }
	public string AddressLine1 { get; set; }
	public string AddressLine2 { get; set; }
	public string City { get; set; }
	public string State { get; set; }
	public string Country { get; set; }
	public int PersonsId { get; set; }
}
DTOs/PersonDto.cs And DTOs/PersonAddress.cs: 
public class PersonsDto
{
	public int ID { get; set; }
	public string LastName { get; set; }
	public string FirstName { get; set; }
	public int Age { get; set; }
	public List<PersonAddressDto> PersonAddresses { get; set; }
}

public class PersonAddressDto
{
	public int PersonAddressId { get; set; }
	public string AddressLine1 { get; set; }
	public string AddressLine2 { get; set; }
	public string City { get; set; }
	public string State { get; set; }
	public string Country { get; set; }
	public int PersonsId { get; set; }
}
Let's have look at the code without the Automapper. 
[HttpGet]
[Route("person-address")]
public IActionResult GetPersonAddress()
{
	var persons = _myWorldDbContext.Persons.Include(_ => _.PersonAddresses).ToList();
	List<PersonsDto> result = new List<PersonsDto>();
	foreach (var person in persons)
	{
		var personDto = new PersonsDto();
		personDto.ID = person.ID;
		personDto.FirstName = person.FirstName;
		personDto.LastName = person.LastName;
		personDto.Age = person.Age;
		personDto.PersonAddresses = new List<PersonAddressDto>();
		foreach (var address in person.PersonAddresses)
		{
			personDto.PersonAddresses.Add(new PersonAddressDto
			{
				AddressLine1 = address.AddressLine1,
				AddressLine2 = address.AddressLine2,
				City = address.City,
				Country = address.Country,
				PersonAddressId = address.PersonAddressId,
				PersonsId = address.PersonsId,
				State = address.State
			}) ;
		}
		result.Add(personDto);
	}
	return Ok(result);
}
  • Here we can observe both parent and child class collection are looped and manually assigned each property value to DTO's
Let's configure the parent and child classes in our 'Profile' class with respective source and destination types.
MapperProfiles/AppProfile.cs:
public class AppProfile:Profile
{
	public AppProfile()
	{
		
		CreateMap<Persons, PersonsDto>();
		CreateMap<PersonAddress, PersonAddressDto>();
	}
}
Now let's take look at the code that uses Automapper. 
[HttpGet]
[Route("person-address-with-auto-mapper")]
public IActionResult GetPersonAddressWithAutoMapper()
{
	var persons = _myWorldDbContext.Persons.Include(_ => _.PersonAddresses).ToList();
	List<PersonsDto> result = _mapper.Map<List<Persons>, List<PersonsDto>>(persons);
	return Ok(result);
}
  • Here we can see the source as 'Persons' collection and destination object as 'PersonDto' collection since we had configured our child object in 'Profile' class, so internally child source object(PersonAddress) data copied into child destination object(PersonAddressDto).

ForMember() Method For Explicit  Property Mapping:

In some cases we might have properties names different in source and destination or we might have defined some custom value with combination source properties then result need to be assigned to single destination properties can be achieved using the 'ForMember()' configuration.

DTOs/PersonOverviewDto.cs And Entities/Person.cs:
// Destination Object
public class PersonOverviewDto
{
	public int ID { get; set; }
	public string FullName { get; set; }
}

// Source Object
public class Persons
{
	public int ID { get; set; }
	public string LastName { get; set; }
	public string FirstName { get; set; }
	public int Age { get; set; }
	public List<PersonAddress> PersonAddresses { get; set; }
}
  • Here 'Persons' class is the source and 'PersonOverviewDto' is the destination. By default, Automapper will copy the properties values whose names are the same in both objects. If the destination object has properties that are not in the source object then their value will be the default value of the property types. Now here I want to do an explicit mapping like in the destination object 'FullName' property value should be combination source object properties like 'FirstName' and 'Last' this can be achieved using 'ForMember' Method in the configuration.
So let's configure our setting in the 'Profile' class as below
MapperProfiles/AppProfile.cs:
public class AppProfile:Profile
{
	public AppProfile()
	{
		CreateMap<Persons, PersonOverviewDto>()
			.ForMember(d => d.FullName, s => s.MapFrom(_ => $"{_.FirstName} {_.LastName}"));
	}
}
  • Here we can observe the 'FullName' value created by combining 'FirstName' and 'LastName' properties of the source object. So 'IMapper' will respect this rule while mapping the 'Persons' and 'PesonOverviewDto' objects.
Our code with Automapper implementation looks as below. 
[HttpGet]
[Route("person-overview")]
public IActionResult GetPersonAddressOverView()
{
	var persons = _myWorldDbContext.Persons.Include(_ => _.PersonAddresses).ToList();
	List<PersonOverviewDto> result = _mapper.Map<List<Persons>, List<PersonOverviewDto>>(persons);
	return Ok(result);
}

IQueryable Mapping:

AutoMapper can be used along with the EntityFramework core IQueryable extension methods. so this can be achieved using 'ProjectTo<DestinationObject>()' extension method.

So here I want to map 'Persons' and 'PersonDto' objects, if we recall we have already configured mapping for these objects in the 'Nested Object Mapping' section above.

So code using the 'ProjectTo<>()' method looks as below.
[HttpGet]
[Route("person-address-with-auto-mapper-extend")]
public IActionResult GetPersonAddressWithAutoMapperExtend()
{
	var persons = _myWorldDbContext.Persons.Include(_ => _.PersonAddresses).ProjectTo<PersonsDto>(_mapper.ConfigurationProvider).ToList();
	return Ok(persons);
}

Video Session:

Support Me!
Buy Me A Coffee PayPal Me

Wrapping Up:

Hopefully, I think this article delivered some useful information on AutoMapper techniques in Asp.Net Core Application. I love to have your feedback, suggestions, and better techniques in the comment section below.

Follow Me:

Labels:

Comments

Post a Comment

Popular posts from this blog

.NET6 Web API CRUD Operation With Entity Framework Core

In this article, we are going to do a small demo on AspNetCore 6 Web API CRUD operations. What Is Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains a programming function that can be requested via HTTP calls to save or fetch the data for their respective clients. Some of the key characteristics of API: Supports HTTP verbs like 'GET', 'POST', 'PUT', 'DELETE', etc. Supports default responses like 'XML' and 'JSON'. Also can define custom responses. Supports self-hosting or individual hosting, so that all different kinds of apps can consume it. Authentication and Authorization are easy to implement. The ideal platform to build REST full services. Create A .NET6 Web API Application: Let's create a .Net6 Web API sample application to accomplish our
6 comments
Read more

Angular 14 Reactive Forms Example

In this article, we will explore the Angular(14) reactive forms with an example. Reactive Forms: Angular reactive forms support model-driven techniques to handle the form's input values. The reactive forms state is immutable, any form filed change creates a new state for the form. Reactive forms are built around observable streams, where form inputs and values are provided as streams of input values, which can be accessed synchronously. Some key notations that involve in reactive forms are like: FormControl - each input element in the form is 'FormControl'. The 'FormControl' tracks the value and validation status of form fields. FormGroup - Track the value and validate the state of the group of 'FormControl'. FormBuilder - Angular service which can be used to create the 'FormGroup' or FormControl instance quickly. Form Array - That can hold infinite form control, this helps to create dynamic forms. Create An Angular(14) Application: Let'
3 comments
Read more

Part-1 Angular JWT Authentication Using HTTP Only Cookie[Angular V13]

In this article, we are going to implement a sample angular application authentication using HTTP only cookie that contains a JWT token. HTTP Only JWT Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing JWT token inside of the cookie then the cookie should be HTTP Only. The HTTP-Only cookie nature is that it will be only accessible by the server application. Client apps like javascript-based apps can't access the HTTP-Only cookie. So if we use authentication with HTTP only JWT cookie then we no need to implement custom logic like adding authorization header or storing token data, etc at our client application. Because once the user authenticated cookie will be automatically sent to the server by the browser on every API call. Authentication API: To implement JWT cookie authentication we need to set up an API. For that, I had created a mock authentication API(Using the NestJS Se
Post a Comment
Read more

Unit Testing Asp.NetCore Web API Using xUnit[.NET6]

In this article, we are going to write test cases to an Asp.NetCore Web API(.NET6) application using the xUnit. xUnit For .NET: The xUnit for .Net is a free, open-source, community-focused unit testing tool for .NET applications. By default .Net also provides a xUnit project template to implement test cases. Unit test cases build upon the 'AAA' formula that means 'Arrange', 'Act' and 'Assert' Arrange - Declaring variables, objects, instantiating mocks, etc. Act - Calling or invoking the method that needs to be tested. Assert - The assert ensures that code behaves as expected means yielding expected output. Create An API And Unit Test Projects: Let's create a .Net6 Web API and xUnit sample applications to accomplish our demo. We can use either Visual Studio 2022 or Visual Studio Code(using .NET CLI commands) to create any.Net6 application. For this demo, I'm using the 'Visual Studio Code'(using the .NET CLI command) editor. Create a fo
6 comments
Read more

A Small Guide On NestJS Queues

NestJS Application Queues helps to deal with application scaling and performance challenges. When To Use Queues?: API request that mostly involves in time taking operations like CPU bound operation, doing them synchronously which will result in thread blocking. So to avoid these issues, it is an appropriate way to make the CPU-bound operation separate background job.  In nestjs one of the best solutions for these kinds of tasks is to implement the Queues. For queueing mechanism in the nestjs application most recommended library is '@nestjs/bull'(Bull is nodejs queue library). The 'Bull' depends on Redis cache for data storage like a job. So in this queueing technique, we will create services like 'Producer' and 'Consumer'. The 'Producer' is used to push our jobs into the Redis stores. The consumer will read those jobs(eg: CPU Bound Operations) and process them. So by using this queues technique user requests processed very fastly because actually
7 comments
Read more

Angular 14 State Management CRUD Example With NgRx(14)

In this article, we are going to implement the Angular(14) state management CRUD example with NgRx(14) NgRx Store For State Management: In an angular application to share consistent data between multiple components, we use NgRx state management. Using NgRx state helps to avoid unwanted API calls, easy to maintain consistent data, etc. The main building blocks for the NgRx store are: Actions - NgRx actions represents event to trigger the reducers to save the data into the stores. Reducer - Reducer's pure function, which is used to create a new state on data change. Store - The store is the model or entity that holds the data. Selector - Selector to fetch the slices of data from the store to angular components. Effects - Effects deals with external network calls like API. The effect gets executed based the action performed Ngrx State Management flow: The angular component needs data for binding.  So angular component calls an action that is responsible for invoking the API call.  Aft
7 comments
Read more

Usage Of CancellationToken In Asp.Net Core Applications

When To Use CancellationToken?: In a web application request abortion or orphan, requests are quite common. On users disconnected by network interruption or navigating between multiple pages before proper response or closing of the browser, tabs make the request aborted or orphan. An orphan request can't deliver a response to the client, but it will execute all steps(like database calls, HTTP calls, etc) at the server. Complete execution of an orphan request at the server might not be a problem generally if at all requests need to work on time taking a job at the server in those cases might be nice to terminate the execution immediately. So CancellationToken can be used to terminate a request execution at the server immediately once the request is aborted or orphan. Here we are going to see some sample code snippets about implementing a CancellationToken for Entity FrameworkCore, Dapper ORM, and HttpClient calls in Asp.NetCore MVC application. Note: The sample codes I will show in
2 comments
Read more

Blazor WebAssembly Custom Authentication From Scratch

In this article, we are going to explore and implement custom authentication from the scratch. In this sample, we will use JWT authentication for user authentication. Main Building Blocks Of Blazor WebAssembly Authentication: The core concepts of blazor webassembly authentication are: AuthenticationStateProvider Service AuthorizeView Component Task<AuthenticationState> Cascading Property CascadingAuthenticationState Component AuthorizeRouteView Component AuthenticationStateProvider Service - this provider holds the authentication information about the login user. The 'GetAuthenticationStateAsync()' method in the Authentication state provider returns user AuthenticationState. The 'NotifyAuthenticationStateChaged()' to notify the latest user information within the components which using this AuthenticationStateProvider. AuthorizeView Component - displays different content depending on the user authorization state. This component uses the AuthenticationStateProvider
6 comments
Read more

How Response Caching Works In Asp.Net Core

What Is Response Caching?: Response Caching means storing of response output and using stored response until it's under it's the expiration time. Response Caching approach cuts down some requests to the server and also reduces some workload on the server. Response Caching Headers: Response Caching carried out by the few Http based headers information between client and server. Main Response Caching Headers are like below Cache-Control Pragma Vary Cache-Control Header: Cache-Control header is the main header type for the response caching. Cache-Control will be decorated with the following directives. public - this directive indicates any cache may store the response. private - this directive allows to store response with respect to a single user and can't be stored with shared cache stores. max-age - this directive represents a time to hold a response in the cache. no-cache - this directive represents no storing of response and always fetch the fr
Post a Comment
Read more

Angular 14 Crud Example

In this article, we will implement CRUD operation in the Angular 14 application. Angular: Angular is a framework that can be used to build a single-page application. Angular applications are built with components that make our code simple and clean. Angular components compose of 3 files like TypeScript File(*.ts), Html File(*.html), CSS File(*.cs) Components typescript file and HTML file support 2-way binding which means data flow is bi-directional Component typescript file listens for all HTML events from the HTML file. Create Angular(14) Application: Let's create an Angular(14) application to begin our sample. Make sure to install the Angular CLI tool into our local machine because it provides easy CLI commands to play with the angular application. Command To Install Angular CLI npm install -g @angular/cli Run the below command to create the angular application. Command To Create Angular Application ng new name_of_your_app Note: While creating the app, you will see a noti
4 comments
Read more