Introduction
This article provides a walkthrough of how to call a Web API from a client application that we created in Part 1.
Let's start by creating a simple Console Application in the existing solution that we have already created.
Step 1: Right-click the Solution Explorer, select "Add New Project" and select "Console Application".
![Add New Project]()
Step 2: Install Microsoft.AspNet.WebApi.SelfHost using the Packager Manager console as shown below. Click on "Tools" then select "Library Package Manager" --> "Package Manager Console" and enter the following command:
![Package Manager Console]()
Install-Package Microsoft.AspNet.WebApi.SelfHost
![Install-Package]()
Step 3: Now add a reference to the TestClient to the SelfHost1 project as in the following:
In Solution Explorer right-click the ClientApp project then select "Add Reference".
In the Reference Manager dialog, under "Solution", select "Projects". Select the SelfHost project. Click "OK" as shown below.
![SelfHost project]()
Step 4: Now open the Program.cs file and add the following implementation. Then run the project by setting TestClient as the Start up project.
using System;
using System.Collections.Generic;
using System.Net.Http;
namespace TestClient
{
class Program
{
static HttpClient client = new HttpClient();
static void Main(string[] args)
{
client.BaseAddress = new Uri("http://localhost:8080");
ListAllBooks();
ListBook(1);
ListBooks("seventh");
Console.WriteLine("Press Enter to quit.");
Console.ReadLine();
}
static void ListAllBooks()
{
//Call HttpClient.GetAsync to send a GET request to the appropriate URI
HttpResponseMessage resp = client.GetAsync("api/books").Result;
//This method throws an exception if the HTTP response status is an error code.
resp.EnsureSuccessStatusCode();
var books = resp.Content.ReadAsAsync<IEnumerable<SelfHost1.book>>().Result;
foreach (var p in books)
{
Console.WriteLine("{0} {1} {2} ({3})", p.Id, p.Name, p.Author, p.Rating);
}
}
static void ListBook(int id)
{
var resp = client.GetAsync(string.Format("api/books/{0}", id)).Result;
resp.EnsureSuccessStatusCode();
var book1 = resp.Content.ReadAsAsync<SelfHost1.book>().Result;
Console.WriteLine("ID {0}: {1}", id, book1.Name);
}
static void ListBooks(string author)
{
Console.WriteLine("Books in '{0}':", author);
string query = string.Format("api/books?author={0}", author);
var resp = client.GetAsync(query).Result;
resp.EnsureSuccessStatusCode();
//This method is an extension method, defined in System.Net.Http.HttpContentExtensions
var books = resp.Content.ReadAsAsync<IEnumerable<SelfHost1.book>>().Result;
foreach (var book in books)
{
Console.WriteLine(book.Name);
}
}
}
}
Summary
In this article, I explained how to call a Web API from a client application.