How to make HTTP call from Controller ? to Use web API's Asp.Net Core C#

Question

I want to make HTTP calls to various services, POST/GET/DELETE.., and read responses JSON AND XML, How do I do this in C# on servers side?

In short: How to make Api call from Asp.Net Core C#.

Client side Ajax doesn't work, (for cross domains)

Answer 1

Use ajax to call controler:

$.ajax({                                        
        type: "GET",      
        url: "/API/Gumtreetoken?user=username&pasword=password",                                       
        success: function (atsakas) {                                       
              alert(atsakas);
        },
        error: function (error) {
              alert("error");         
        }
});

And, from controller I use HTTPClient to make POST call and get needed values from XML responce.

    [Authorize]
    [Route("API/Gumtreetoken")]
    public IActionResult GumtreePost(string user, string pasword)
    {
        string atsakas = "";
        string token = "";
        string id = "";

        using (HttpClient client = new HttpClient())
        {
            //parametrai (PARAMS of your call)
            var parameters = new Dictionary<string, string> { { "username", "YOURUSERNAME" }, { "password", "YOURPASSWORD" } };
            //Uzkoduojama URL'ui 
            var encodedContent = new FormUrlEncodedContent(parameters);               
            try
            {
                //Post http callas.
                HttpResponseMessage response =  client.PostAsync("https://feed-api.gumtree.com/api/users/login", encodedContent).Result;
                //nesekmes atveju error..
                response.EnsureSuccessStatusCode();
                //responsas to string
                string responseBody = response.Content.ReadAsStringAsync().Result;
                
                atsakas = responseBody;
               
            }
            catch (HttpRequestException e)
            {
                Console.WriteLine("\nException Caught!");
                Console.WriteLine("Message :{0} ", e.Message);
            }
            //xml perskaitymui
            XmlDocument doc = new XmlDocument();
            //xml uzpildomas api atsakymu
            doc.LoadXml(@atsakas);
            //iesko TOKEN
            XmlNodeList xmltoken = doc.GetElementsByTagName("user:token");
            //iesko ID
            XmlNodeList xmlid = doc.GetElementsByTagName("user:id");

            token = xmltoken[0].InnerText;
            id = xmlid[0].InnerText;

            atsakas = "ID: " + id + "   Token: " + token;
            
        }
        return Json(atsakas);
    }

This should be Async, so, you could do like this:

    [Authorize]
    [Route("API/Gumtreetoken")]
    public async Task<IActionResult> GumtreePost(string user, string pasword)
    {
        string atsakas = "";
        string token = "";
        string id = "";
        using (HttpClient client = new HttpClient())
        {
            var parameters = new Dictionary<string, string> { { "username", "YOURUSERNAME" }, { "password", "YOURPASSWORD" } };
            var encodedContent = new FormUrlEncodedContent(parameters);               
            try
            {
                HttpResponseMessage response = await client.PostAsync("https://feed-api.gumtree.com/api/users/login", encodedContent);
                response.EnsureSuccessStatusCode();
                string responseBody = await response.Content.ReadAsStringAsync();                    
                atsakas = responseBody;                   
            }
            catch (HttpRequestException e)
            {
                Console.WriteLine("\nException Caught!");
                Console.WriteLine("Message :{0} ", e.Message);
            }
            XmlDocument doc = new XmlDocument();
            doc.LoadXml(@atsakas);
            XmlNodeList xmltoken = doc.GetElementsByTagName("user:token");
            XmlNodeList xmlid = doc.GetElementsByTagName("user:id");
            token = xmltoken[0].InnerText;
            id = xmlid[0].InnerText;
            atsakas = "ID: " + id + "   Token: " + token;
        }
        return Json(atsakas);
    }

Answer 2

Try this code: To make Api call from Asp.Net Core, Server Side (C#).

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;

namespace core.api.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class ValuesController : ControllerBase
    {
        [HttpGet]
        public async  Task<ActionResult<string>> Get()
        {
            string url="https://jsonplaceholder.typicode.com/todos"; // sample url
            using (HttpClient client = new HttpClient())
            {
                return  await client.GetStringAsync(url);
            }
        }
    }

}