Writing code

So far, we have cooked the things required for writing code for our REST web client; in this section, we will be writing actual code:

1. Add a simple code to call or consume your product APIs.

If you created a new project in the same solution (refer to step 1 of the section Cooking the web client), please make sure that the project Product API is running before you start your web client project.

2. Add a new class (Ctrl + Shift + C) in the Client folder and name it RestSharpWebClient.

3. Now open the RestSharpWebClient class and add the following code:

private readonly RestClient _client = new RestClient("http://localhost:10065/api/");

The preceding code initializes RestClient of RestSharp and accepts the base URL as a string or a URI.

URI stands for Uniform Resource Identifier and is a representation of a string used to identify resources.

You may come across a scenario where there are multiple environments; in this case, you should store a URI where you point it as per your environment. For example, you can have the URI http://devserver:10065/api/ for your development environment or the URI http://testenv:10068/api/ for your QA environment. You should store these keys in the config file or somewhere similar so that the values are easily accessible. We recommend using new RestClient(somevariableforURI);.

In our application, product APIs are running on localhost and the listening port 10065. This may be different in your case.

Let's discuss the following code snippet to call or consume the GET /api/product
/productlist resource and populate the complete product list, as follows:

public List<ProductViewModel> GetProducts()
{
  var request = new RestRequest("product/productlist", Method.GET);
  var response = _client.Execute<List<ProductViewModel>>(request);
  return response.Data ?? new List<ProductViewModel> {new
  ProductViewModel()};
}

Here, we are making a GET request using RestRequest, where we passed a resource and method.

To get a particular product using productid, enter the following code:

public ProductViewModel GetProductDetails(string productId)
{
  var request = new RestRequest("product/{productid}", Method.GET);
  request.AddParameter("productid", productId);
  var response = _client.Execute<ProductViewModel>(request);
  return response.Data ?? new ProductViewModel();
}

In the preceding code block, the GetProductDetails method does a similar thing to the method GetProducts. The difference is that it accepts the parameter productId.

The following is the complete code of our REST client:

public class RestSharpWebClient
{
  private readonly RestClient _client = new
  RestClient("http://localhost:10065/api/");
  public List<ProductViewModel> GetProducts()
  {
    var request = new RestRequest("product/productlist", 
    Method.GET);
    var response = _client.Execute<List<ProductViewModel>>
    (request);
    //To avoid any exception lets return an empty view model
    //On production environment return exact exception or your 
    custom code
    return response.Data ?? new List<ProductViewModel> {new
    ProductViewModel()};
  }
  public ProductViewModel GetProductDetails(string productId)
  {
    var request = new RestRequest("product/{productid}", 
    Method.GET);
    request.AddParameter("productid", productId);
    var response = _client.Execute<ProductViewModel>(request);
    //To avoid any exception lets return an empty view model
    //On production environment return exact exception or your 
    custom code
    return response.Data ?? new ProductViewModel();
  }
  public bool AddProduct(ProductViewModel product)
  {
    var request = new RestRequest("product/addproduct", 
    Method.POST);
    request.AddBody(product);
    var response = _client.Execute(request);
    return response.StatusCode == HttpStatusCode.OK;
  }
  public bool UpdateProduct(string id, ProductViewModel product)
  {
    var request = new RestRequest("updateproduct", Method.PUT);
    request.AddQueryParameter("productid", id);
    request.AddBody(product);
    var response = _client.Execute(request);
    return response.StatusCode == HttpStatusCode.NoContent;
  }
  public bool DeleteProduct(string id, ProductViewModel product)
  {
    var request = new RestRequest("deleteproduct", Method.DELETE);
    request.AddQueryParameter("productid", id);
    request.AddBody(product);
    var response = _client.Execute(request);
    return response.StatusCode == HttpStatusCode.NoContent;
  }
}

With the preceding code snippet, you have now added the functionality that will call and consume your product APIs.