Skip to main content

A Sample On HttpClientFactory Using Typed Client Technique In .Net Core Application

In .Net Core, using HttpClientFacotory is the recommended way to consume the Rest API. The HttpClientFactory can be implemented using the following techniques.

Typed Client:

Typed Client technique is to implement or create a separate entity or class file per API domain. So all Http communication implementations are registered in a specific class per API domain. In this approach, each entity or class will be injected with 'System.Net.Http.HttpClient' object by the 'HttpClienFacotry'. So in this approach, we will not use 'HttpClientFactory' directly like we did for 'Named Client' and 'Using HttpRequestMessage Object' techniques.

In simple words for consuming one third-party rest API need to create a specific class for it, if we have 'n' number of rest APIs to consume in our project then we need to create 'n' number of classes to implement the HttpClientFactory logic specific to the domains of rest APIs.

HttpClientFactory Request Flow:


Click here for a better understanding of the working flow of HttpClientFactory.

ThirdParty Test APIs:

So to understand and implement a sample on HttpClientFactory using the named technique we need to have external APIs. So were are going to use freely hosted rest APIs for a developer to use and learn like below:
JSONPlaceholder:
https://jsonplaceholder.typicode.com/

Dummy Rest API:
http://dummy.restapiexample.com/

Create A .Net Core Sample API Project:

To understand and to learn the Typed Client technique of HttpClientFactory we are going to do a sample application. So to start for creating a sample application we can use either Visual Studio 2019 or Visual Studio Code.

Install NewtonSoft.Json Package:

For easy steps to serialize and deserialize of JSON response, we are going to use the NewtonSoft.JSON package.
CLI Command:

dotnet add package Newtonsoft.Json
PackageManager:

Install-Package Newtonsoft.Json

Create A Typed Client Of JSONPlaceHolder Rest API:

Now to consume the 'Todos' endpoint of 'JsonPlaceHolder' Rest API we are going to create a separate typed client.
RestCalls/JsonPlaceHolderClient.cs:
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using TypedClientApi.Model;

namespace TypedClientApi.RestCalls
{
    public class JsonPlaceHolderClient
    {
        public readonly HttpClient _httpClient;

        public JsonPlaceHolderClient(HttpClient httpClient)
        {
            httpClient.BaseAddress = new Uri("https://jsonplaceholder.typicode.com");
            _httpClient = httpClient;
        }
    }
}
  • 'JsonPlaceHolderClient.cs' is a Typed Client of 'JsonPlaceHolder' API, all GET, POST, DELETE action methods will implemented in this class.
  • 'System.Net.Http.HttpClient' object injected into our typed client. In this approach, HttpClientFacotry will not be used directly.
  • In this constructor we can configure our HttpClient object with 'domain', 'default-headers','default-keys', etc. These default configurations can also be configured at the 'Startup.cs' file also.
Since we are going to consume the todos object, let's create 'Todo.cs' to hold the API response data.
Model/Todo.cs:
namespace TypedClientApi.Model
{
    public class Todo
    {
        public int UserId { get; set; }
        public int Id { get; set; }
        public string Title { get; set; }
        public bool Completed { get; set; }
    }
}
Now let's implement 'Todos' endpoint get method as follows:
RestCalls/JsonPlaceHolderClient.cs:
public async Task<List<Todo>> GetTodos()
{
	var response = await _httpClient.GetAsync("/todos");

	if (response.IsSuccessStatusCode)
	{
		string responseString = await response.Content.ReadAsStringAsync();
		List<Todo> todos = JsonConvert.DeserializeObject<List<Todo>>(responseString);
		return todos;
	}
	return new List<Todo>();
}
  • (Line 3) HttpClient object is used to trigger the 'Todo' endpoint. The HttpClient object is made of all asynchronous operations like 'GetAsync', 'PostAsync', 'DeleteAsync' etc. Since we assigned the domain name at the time of constructor initialization, so for endpoints can be declared with a relative path.
  • So on receiving the successful response, we deserialize the response to the object.
Now register the 'JsonPlaceHoderClient' typed client in the Startup.cs file to make this typed client available to HttpClientFactory. So on registering in the 'Startup.cs' file, the typed client(eg: 'JsonPlaceHolderClient') will become the injectable service.
Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
	services.AddControllers();
	services.AddHttpClient<JsonPlaceHolderClient>();
}
Let's write a 'Test' controller endpoint to consume this 'Todo' API as follows:
Controllers/TestController.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using TypedClientApi.Model;
using TypedClientApi.RestCalls;

namespace TypedClientApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class TestController : ControllerBase
    {
        private readonly JsonPlaceHolderClient _jsonPlaceHolderClient;
        public TestController(JsonPlaceHolderClient jsonPlaceHolderClient)
        {
            _jsonPlaceHolderClient = jsonPlaceHolderClient;
        }

        [HttpGet]
        [Route("all-todos")]
        public async Task<IActionResult> GetTodos()
        {
            List<Todo> todos = await _jsonPlaceHolderClient.GetTodos();
            return Ok(todos);
        }
    }
}
  • (Line: 17) 'JsonPlaceHolderClient' rest-client injected to our test controller.
  • (Line: 22-28) get action method to fetch all todos
Now run the application and checks the todo's JSON response data as below.

Create A Type Client Of DummyExampleRestAPI:

Here we are creating a new 'DummyExampleRestAPI' to understand how it looks in the real-time application while using the Typed Client technique.

The employee endpoint of 'DummyExampleRestAPI' response objects to be created like below.
Models/Employee.cs:
using Newtonsoft.Json;
using System.Collections.Generic;

namespace TypedClientApi.Model
{
    public class Employee
    {
        [JsonProperty(PropertyName = "id")]
        public string Id { get; set; }

        [JsonProperty(PropertyName = "employee_name")]
        public string EmployeeName { get; set; }
        [JsonProperty(PropertyName = "employee_salary")]
        public string EmployeeSalary { get; set; }
        [JsonProperty(PropertyName = "employee_age")]
        public string EmplyeeAge { get; set; }
        [JsonProperty(PropertyName = "profile_image")]
        public string ProfileImage { get; set; }
    }

    public class DummyExampleApiResult
    {
        public string Status { get; set; }
        public List<Employee> Data { get; set; }
    }
}
Now let's implement 'DummyExampleRestAPI' typed client as below:
RestCalls/DummyExampleRestClient.cs: 
using Newtonsoft.Json;
using System;
using System.Net.Http;
using System.Threading.Tasks;
using TypedClientApi.Model;

namespace TypedClientApi.RestCalls
{
    public class DummyExampleRestClient
    {
        private readonly HttpClient _httpClient;
        public DummyExampleRestClient(HttpClient httpClient)
        {
            httpClient.BaseAddress = new Uri("http://dummy.restapiexample.com");
            _httpClient = httpClient;
        }

        public async Task<DummyExampleApiResult> GetEmployees()
        {
            var response = await _httpClient.GetAsync("/api/v1/employees");
            if (response.IsSuccessStatusCode)
            {
                string responseString = await response.Content.ReadAsStringAsync();
                DummyExampleApiResult employees = JsonConvert.DeserializeObject<DummyExampleApiResult>(responseString);
                return employees;
            }
            return new DummyExampleApiResult();
        }
    }
}
Now register 'DummyExampleRestClient' in startup.cs as below:
Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
	services.AddControllers();
	services.AddHttpClient<JsonPlaceHolderClient>();
	services.AddHttpClient<DummyExampleRestClient>();
}
Now inject our 'DummyExampleRestClient' into the TestController as below:
Controllers/TesController.cs: 
private readonly JsonPlaceHolderClient _jsonPlaceHolderClient;
private readonly DummyExampleRestClient _dummyExampleRestClient;
public TestController(
	JsonPlaceHolderClient jsonPlaceHolderClient,
	DummyExampleRestClient dummyExampleRestClient)
{
	_jsonPlaceHolderClient = jsonPlaceHolderClient;
	_dummyExampleRestClient = dummyExampleRestClient;
}
Now add get action methods to fetch employee data as below:
Controllers/TestController.cs:
[HttpGet]
[Route("all-employee")]
public async Task<IActionResult> GetEmployees()
{
	DummyExampleApiResult employees = await _dummyExampleRestClient.GetEmployees();
	return Ok(employees);
}

Now run the application and checks the JSON response data of employee endpoint like below:

Default HttpClient Configuration At Startup.Cs:

On recalling the previous steps we know that API 'domain', 'default-headers', 'default-keys' can be configured in typed client constructor. But we have another option to configure them in the startup .cs file at the time of registering those typed clients

Startup.cs:
public void ConfigureServices(IServiceCollection services)
{
	services.AddControllers();
	services.AddHttpClient<JsonPlaceHolderClient>(client =>
	{
		client.BaseAddress = new Uri("https://jsonplaceholder.typicode.com");
		//client.DefaultRequestHeaders
		// client.Timeout
		// client.DefaultRequestVersion
	});
	services.AddHttpClient<DummyExampleRestClient>(client =>
	{
		client.BaseAddress = new Uri("http://dummy.restapiexample.com");
		//client.DefaultRequestHeaders
		// client.Timeout
		// client.DefaultRequestVersion
	});
}
Now we can remove the default configurations from the constructor in the typed clients as below: 
namespace TypedClientApi.RestCalls
{
    public class JsonPlaceHolderClient
    {
        public readonly HttpClient _httpClient;

        public JsonPlaceHolderClient(HttpClient httpClient)
        {
            _httpClient = httpClient;
        }
    }
}

namespace TypedClientApi.RestCalls
{
    public class DummyExampleRestClient
    {
        private readonly HttpClient _httpClient;
        public DummyExampleRestClient(HttpClient httpClient)
        
            _httpClient = httpClient;
        }
    }
}
Finally, we have implemented a sample using the Typed Client technique in .net core application.

Support Me!
Buy Me A Coffee PayPal Me

Wrapping Up:

Hopefully, I think this article delivered some useful information about HttpClient implementation using the Typed Client technique in .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

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

.NET 7 Web API CRUD Using Entity Framework Core

In this article, we are going to implement a sample .NET 7 Web API CRUD using the Entity Framework Core. Web API: Web API is a framework for building HTTP services that can be accessed from any client like browser, mobile devices, and desktop apps. In simple terminology API(Application Programming Interface) means an interface module that contains programming functions that can be requested via HTTP calls either to fetch or update 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 the REST full services. Install The SQL Server And SQL Management Studio: Let's install the SQL server on our l
3 comments
Read more

.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

ReactJS(v18) JWT Authentication Using HTTP Only Cookie

In this article, we will implement the ReactJS application authentication using the HTTP-only cookie. HTTP Only Cookie: In a SPA(Single Page Application) Authentication JWT token either can be stored in browser 'LocalStorage' or in 'Cookie'. Storing the 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 the authentication with HTTP-only JWT cookie then we no need to implement the 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 authenticate our client application with JWT HTTP-only cookie, I developed a NetJS(which is a node) Mock API. Check the GitHub link and read the document on G
2 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
8 comments
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
7 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

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

ReactJS(v18) Authentication With JWT AccessToken And Refresh Token

In this article, we are going to do ReactJS(v18) application authentication using the JWT Access Token and Refresh Token. JSON Web Token(JWT): JSON Web Token is a digitally signed and secured token for user validation. The JWT is constructed with 3 important parts: Header Payload Signature Create ReactJS Application: Let's create a ReactJS application to accomplish our demo. npx create-react-app name-of-your-app Configure React Bootstrap Library: Let's install the React Bootstrap library npm install react-bootstrap bootstrap Now add the bootstrap CSS reference in 'index.js'. src/index.js: import 'bootstrap/dist/css/bootstrap.min.css' Create A React Component 'Layout': Let's add a React component like 'Layout' in 'components/shared' folders(new folders). src/components/shared/Layout.js: import Navbar from "react-bootstrap/Navbar"; import { Container } from "react-bootstrap"; import Nav from "react-boot
Post a Comment
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
8 comments
Read more