How to consume oauth2 api using asp.net core

Question

Hi

I want to know How to consume oauth2 api using asp.net core.

I want to call third party API in asp.net core. I want to know where can i set all my config files like base url, client id,secret key in .Net core

regards,

Manish

Prasad Raveendran · Answer

In .NET 6.0, the startup configuration has been simplified with the introduction of the simplified hosting model. The Startup.cs file is not required by default, but you can still use it if you prefer. However, the convention has shifted towards using the Program.cs file for configuration. Here's how you can set up the API consumption using OAuth2 in .NET 6.0: Create Configuration Model: Create a model to represent the configuration values for the OAuth2 API. For example: public class ApiConfig { public string BaseUrl { get; set; } public string ClientId { get; set; } public string ClientSecret { get; set; } } Configure AppSettings.json: Add the API configuration values to your appsettings.json file: { "ApiConfig": { "BaseUrl": "https://api.example.com", "ClientId": "your_client_id", "ClientSecret": "your_client_secret" } } Configure Program.cs: In the CreateHostBuilder method of Program.cs , configure your application: using Microsoft.Extensions.Configuration; var builder = WebApplication.CreateBuilder(args); // Other configurations... builder.Services.Configure (builder.Configuration.GetSection("ApiConfig")); builder.Services.AddHttpClient("ApiClient", client => { var apiConfig = builder.Configuration.GetSection("ApiConfig").Get (); client.BaseAddress = new Uri(apiConfig.BaseUrl); client.DefaultRequestHeaders.Add("Accept", "application/json"); // Add any other headers or configurations needed }); // Other services... var app = builder.Build(); // Configure middleware, routes, etc. app.Run(); Use HttpClient in Controller or Service: Inject the HttpClient where you need it (e.g., in a controller or service): public class MyController : ControllerBase { private readonly IHttpClientFactory _httpClientFactory; public MyController(IHttpClientFactory httpClientFactory) { _httpClientFactory = httpClientFactory; } public async Task MyAction() { var client = _httpClientFactory.CreateClient("ApiClient"); // Use the client to make requests to the OAuth2 API // Example: var response = await client.GetAsync("/api/resource"); return Ok(); } } This is a basic example, and you might need to adjust it based on the specifics of the OAuth2 provider and API you are working with. Ensure that you handle OAuth2 authentication appropriately, such as obtaining and refreshing access tokens. Please do let me know if you need additional information

Sachin Singh · Answer

here is an example { "ApiSettings": { "BaseUrl": "https://api.example.com", "ClientId": "your-client-id", "ClientSecret": "your-client-secret" } } Startup or Main() using Microsoft.Extensions.DependencyInjection; public class Startup { public void ConfigureServices(IServiceCollection services) { // Configure HttpClient services.AddHttpClient("YourApiClient", client => { client.BaseAddress = new Uri(Configuration["ApiSettings:BaseUrl"]); client.DefaultRequestHeaders.Add("Accept", "application/json"); // Add any other headers or configurations as needed }); // Other service configurations... services.AddControllers(); } public void Configure(IApplicationBuilder app, IWebHostEnvironment env) { // App configurations... } } using System.Net.Http; using System.Threading.Tasks; using Microsoft.AspNetCore.Mvc; using Microsoft.Extensions.Configuration; [ApiController] [Route("api/[controller]")] public class YourController : ControllerBase { private readonly IHttpClientFactory _httpClientFactory; private readonly IConfiguration _configuration; public YourController(IHttpClientFactory httpClientFactory, IConfiguration configuration) { _httpClientFactory = httpClientFactory; _configuration = configuration; } [HttpGet] public async Task GetDataFromApi() { var client = _httpClientFactory.CreateClient("YourApiClient"); // Set authorization header for OAuth2 (assuming your API uses OAuth2) client.DefaultRequestHeaders.Add("Authorization", "Bearer your-access-token"); // Make a request to the API var response = await client.GetAsync("/api/some-endpoint"); if (response.IsSuccessStatusCode) { // Process successful response var content = await response.Content.ReadAsStringAsync(); return Ok(content); } else { // Handle error response return StatusCode((int)response.StatusCode, response.ReasonPhrase); } } }

Sachin Singh · Answer

Here is the revised example in .NET 6 appsettings.json { "ApiSettings": { "BaseUrl": "https://api.example.com", "ClientId": "your-client-id", "ClientSecret": "your-client-secret" } } Program.cs using Microsoft.Extensions.DependencyInjection; var builder = WebApplication.CreateBuilder(args); builder.Services.AddHttpClient("YourApiClient", client => { client.BaseAddress = new Uri(builder.Configuration["ApiSettings:BaseUrl"]); client.DefaultRequestHeaders.Add("Accept", "application/json"); // Add any other headers or configurations as needed }); // Other service configurations... var app = builder.Build(); app.MapControllers(); app.Run(); API Controller using System.Net.Http; using System.Threading.Tasks; using Microsoft.AspNetCore.Mvc; using Microsoft.Extensions.Configuration; [ApiController] [Route("api/[controller]")] public class YourController : ControllerBase { private readonly IHttpClientFactory _httpClientFactory; private readonly IConfiguration _configuration; public YourController(IHttpClientFactory httpClientFactory, IConfiguration configuration) { _httpClientFactory = httpClientFactory; _configuration = configuration; } [HttpGet] public async Task GetDataFromApi() { var client = _httpClientFactory.CreateClient("YourApiClient"); // Set authorization header for OAuth2 (assuming your API uses OAuth2) client.DefaultRequestHeaders.Add("Authorization", "Bearer your-access-token"); // Make a request to the API var response = await client.GetAsync("/api/some-endpoint"); if (response.IsSuccessStatusCode) { // Process successful response var content = await response.Content.ReadAsStringAsync(); return Ok(content); } else { // Handle error response return StatusCode((int)response.StatusCode, response.ReasonPhrase); } } }

Manish Vadukul · Answer

Hi Sachin, This is good example. Could you please give me full example in .NET core 6.0. I can see there is lot of difference in .NET core 3.1 and 6.0. If you could write for me small .NET core 6.0 Oauth2.0 cusuming API. So it include all programe.cs settings and app settings too. It will be really appreciated. regards, Manish

Manish Vadukul · Answer

Hi Sachin What should i put here ? in Bearer your-access-token and /api/some-endpoint // Set authorization header for OAuth2 (assuming your API uses OAuth2) client.DefaultRequestHeaders.Add("Authorization", "Bearer your-access-token"); // Make a request to the API var response = await client.GetAsync("/api/some-endpoint"); If you are okay than please send me some live test example with link. I don't know how this access Bearer Token to ? Thanks

Manish Vadukul · Answer

Hi Thanks for your answer. Which is really helpful. How can i do consume same Oauth2 rest api using Blazor server side application ? I want to know where can i set all my config files like base url, client id,secret key in Blazor. And show data in page from Rest API. regards, Manish