Consume Web API in a .NET C# client
December 19, 2013 3 Comments
Recently I have written a console client in C# to consume those web services developed in my previous post by using APS.NET Web API 2 and Microsoft Entity Framework 6.
I started with a new Console Application (called WebApiClient) in C# in Visual Studio 2013, and then installed the Microsoft ASP.NET Web API Class Libraries using NuGet. Lastly, I added Employee.cs (model class) which was used by web services as my data structure.
The following is a web client program in C# (Program.cs):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net.Http;
using System.Net.Http.Headers;
namespace WebApiClient
{
class Program
{
static void Main(string[] args)
{
HttpClient client = new HttpClient();
string baseUrl = "http://localhost:55142";
client.BaseAddress = new Uri(baseUrl);
// Add an Accept header for JSON format.
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
//New Employee Record URL
int anEmpId = -1;
string serviceUrl;
// 1. Post a new employee
serviceUrl="api/employee";
Console.WriteLine("1. Add an employee by sending POST {0}/{1} \r\n", baseUrl, serviceUrl);
Console.WriteLine("The following new employee is added \r\n");
var anEmployee = new Employee() {
lastname = "Smith",
firstname = "Adam",
title = "Economist",
titleofcourtesy = "Dr.",
birthdate = Convert.ToDateTime("1958-12-05 "),
hiredate = Convert.ToDateTime("1990-01-01"),
address = "188 Bay Street",
city = "London",
region = "",
postalcode = "A1B 2Z3",
country = "UK",
phone = "(71) 234-8228",
mgrid = 1};
HttpResponseMessage response = client.PostAsJsonAsync(serviceUrl, anEmployee).Result;
if (response.IsSuccessStatusCode)
{
// display the new employee
Console.WriteLine("firstname={0}", anEmployee.firstname);
Console.WriteLine("lastname={0}", anEmployee.lastname);
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
Console.WriteLine("\r\nCheck your database table. Press any key to continue...\r\n");
Console.ReadKey();
// 2. Get all employees.
serviceUrl="api/employee";
Console.WriteLine("2. Get All Employee by sending GET {0}/{1} \r\n", baseUrl, serviceUrl);
response = client.GetAsync(serviceUrl).Result; // Blocking call!
if (response.IsSuccessStatusCode)
{
// Parse the response body. Blocking!
var employees = response.Content.ReadAsAsync<IEnumerable<Employee>>().Result;
foreach (var e in employees)
{
if (e.firstname.Equals("Adam") & e.lastname.Equals("Smith"))
{
anEmpId = e.empid;
Console.ForegroundColor = ConsoleColor.Red;
Console.WriteLine("{0};\t{1};\t{2};\t{3}", e.empid, e.firstname, e.lastname, e.title);
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("\r\nThe new employee is with empid={0}\r\n", anEmpId);
Console.ForegroundColor = ConsoleColor.Gray;
}
else
{
Console.WriteLine("{0};\t{1};\t{2};\t{3}", e.empid, e.firstname, e.lastname, e.title);
}
}
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
Console.WriteLine("\r\nPress any key to continue...\r\n");
Console.ReadKey();
// 3. Get an employee by empid
if (anEmpId>0)
{
serviceUrl = "api/employee/" + anEmpId.ToString();
}
else
{
serviceUrl = "api/employee/1";
anEmpId = 1;
}
Console.WriteLine("3. Get the employee with empid={0} by sending GET {1}/{2} \r\n", anEmpId, baseUrl, serviceUrl);
response = client.GetAsync(serviceUrl).Result; // Blocking call!
if (response.IsSuccessStatusCode)
{
// Parse the response body. Blocking!
var a_employee = response.Content.ReadAsAsync<Employee>().Result;
Console.WriteLine("emid={0}", a_employee.empid);
Console.WriteLine("FirstName={0}", a_employee.firstname);
Console.WriteLine("LastName={0}", a_employee.lastname);
Console.WriteLine("Title={0}", a_employee.title);
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
Console.WriteLine("\r\nPress any key to continue...\r\n");
Console.ReadKey();
// 4. Update an employee by empid
Console.WriteLine("4. Update an employee with empid = {0} by sending PUT {1}/{2} \r\n", anEmpId, baseUrl, serviceUrl);
response = client.GetAsync(serviceUrl).Result; // Blocking call!
if (response.IsSuccessStatusCode)
{
// Retrieve the record first
var a_employee = response.Content.ReadAsAsync<Employee>().Result;
Console.WriteLine("The record is retrieved before update: \r\n");
Console.WriteLine("emid={0}", a_employee.empid);
Console.WriteLine("FirstName={0}", a_employee.firstname);
Console.WriteLine("LastName={0}", a_employee.lastname);
Console.WriteLine("Title={0}", a_employee.title);
// Update the tile field of the record
a_employee.title = "Senior Economist";
response = client.PutAsJsonAsync(serviceUrl, a_employee).Result;
if (response.IsSuccessStatusCode)
{
Console.WriteLine("\r\nThe record with empid={0} was updated with the following: \r\n", anEmpId);
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("Title={0}", a_employee.title);
Console.ForegroundColor = ConsoleColor.Gray;
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
Console.WriteLine("\r\nCheck your database table. Press any key to continue...\r\n");
Console.ReadKey();
// 5. delete an employee added in step 1
Console.WriteLine("4. Delete an employee with empid = {0} by sending DELETE {1}/{2} \r\n", anEmpId, baseUrl, serviceUrl);
response = client.DeleteAsync(serviceUrl).Result;
if (response.IsSuccessStatusCode)
{
Console.ForegroundColor = ConsoleColor.Yellow;
Console.WriteLine("The record with empid={0} was deleted.", anEmpId);
Console.ForegroundColor = ConsoleColor.Gray;
}
else
{
Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
}
Console.WriteLine("\r\nCheck your database table.\r\n");
}
}
}
Henry Chen 