How to Consume Web Api in xamarin CrossPlatform Application

Question

I have created web api that retrieves data from SQL database. I need to consume web api in xamrin for android and xamarin for iOS. as of now xamarin for android. I am not sure h

Answer 1

Here is how I would use this service from just about any project (including Xamarin projects).

First, get rid of the line in your Global.asax file that says this:

GlobalConfiguration.Configuration.Formatters.XmlFormatter.SupportedMediaTypes.Clear();

Generally speaking this is bad practice. You want to have at least the XML and JSON formatters available because in a restful environment it is up to the consumers to determine what type of serialization they need/want.

Next, I would use the System.Net.Http.HttpClient class to interact with this service.

Interacting with the Web Api service from this point is fairly straightforward. Here are some examples.

public async List<Dept> GetDepts()
{
     using(var client = new HttpClient())
     {
          client.BaseAddress = new Uri("http://<ipAddress:port>/");
          client.DefaultRequestHeaders.Accept.Clear();
          client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

          return await client.GetAsync("/api/dept");
     }
}

public async Task<Dept> GetDept(int id)
{
     using(var client = new HttpClient())
     {
          client.BaseAddress = new Uri("http://<ipAddress:port>/");
          client.DefaultRequestHeaders.Accept.Clear();
          client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

          var result = await client.GetAsync(string.format("/api/dept/{0}", id));

          return JsonConvert.DeserializeObject<Dept>(await result.Content.ReadAsStringAsync());
     }
}

public async Task AddDept(Dept dept)
{
     using(var client = new HttpClient())
     {
          client.BaseAddress = new Uri("http://<ipAddress:port>/");

          await client.PostAsJsonAsync("/api/dept", dept);
     }
}

public async Task UpdateDept(Dept dept)
{
     using(var client = new HttpClient())
     {
          client.BaseAddress = new Uri("http://<ipAddress:port>/");

          await client.PutAsJsonAsync(string.format("/api/dept/{0}", dept.no), dept);
     }
}

public async Task DeleteDept(int id)
{
     using(var client = new HttpClient())
     {
          client.BaseAddress = new Uri("http://<ipAddress:port>/");

          client.DeleteAsync(string.format("/api/dept/{0}", id));
     }
}

That should get you started in the right direction anyway. This could definitely get cleaned up and I wrote it freehand so there may be some typos.

Update

Update your MainActivity.cs

Instead of int id = Convert.ToInt32(txtValue1)

Use

int id = Convert.ToInt32(txtValue1.Text);

Instead of GetButton.Click += GetDept(id);

Use

GetButton.Click += async (sender, args) => {
   var dept = await GetDept(id);

   No.Text = dept.no;
   Name.Text = dept.name
}