Xamarin.Forms Consume Rest Service - rest

Question

I'm new to Xamarin and developing native apps in general (I have made html5 apps in the past).
I have started on a Xamarin.Forms project and I'm trying to contact a REST like API (need to GET an URL which will return a json array).
Normally from C# I would use RestSharp and perform this call using the RestClient.
I'm not having any luck installing that package from Xamarin Studio though, but I have got the Microsoft HTTP Libraries installed.
I'm pretty sure this is a very trivial task to perform, I just haven't been able to adapt the samples I have found online to work for me.
Anyone who could post how this is done please (remember I'm new to this so don't expect me to understand everything that is different from say a normal console app)?

Answer 1

It is easy with HTTP Client and JSON.NET here is a example of a GET:
public async Task<List<Appointment>> GetDayAppointments(DateTime day)
{
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Add("Authorization", "Bearer " + App.apiToken);
//Your url.
string resourceUri = ApiBaseAddress;
HttpResponseMessage result = await client.GetAsync (resourceUri, CancellationToken.None);
if (result.IsSuccessStatusCode) {
try {
return GetDayAppointmentsList(result);
} catch (Exception ex) {
Console.WriteLine (ex.Message);
}
} else {
if(TokenExpired(result)){
App.SessionExpired = true;
App.ShowLogin();
}
return null;
}
return null;
}
private List<Appointment> GetDayAppointmentsList(HttpResponseMessage result){
string content = result.Content.ReadAsStringAsync ().Result;
JObject jresponse = JObject.Parse (content);
var jarray = jresponse ["citas"];
List<Appointment> AppoinmentsList = new List<Appointment> ();
foreach (var jObj in jarray) {
Appointment newApt = new Appointment ();
newApt.Guid = (int)jObj ["id"];
newApt.PatientId = (string)jObj ["paciente"];
newApt.Name = (string)jObj ["nombre"];
newApt.FatherLstName = (string)jObj ["paterno"];
newApt.MotherLstName = (string)jObj ["materno"];
string strStart = (string)jObj ["horaIni"];
TimeSpan start;
TimeSpan.TryParse (strStart, out start);
newApt.StartDate = start;
string strEnd = (string)jObj ["horaFin"];
TimeSpan end;
TimeSpan.TryParse (strEnd, out end);
newApt.EndDate = end;
AppoinmentsList.Add (newApt);
}
return AppoinmentsList;
}

Answer 2

I use System.Net.WebClient and our asp.net WebAPI interface:
public string GetData(Uri uri)
{//uri like "https://webapi.main.cz/api/root"
string ret = "ERROR";
try
{
using (WebClient webClient = new WebClient())
{
//You can set webClient.Headers there
webClient.Encoding = System.Text.Encoding.UTF8;
ret = webClient.DownloadString(uri));//Test some data received
//In ret you can have JSON string
}
}
catch (Exception ex) { ret = ex.Message; }
return ret;
}
4
public string SendData(Uri uri, byte[] data)
{//uri like https://webapi.main.cz/api/PostCheckLicence/
string ret = "ERROR";
try
{
using (WebClient webClient = new WebClient())
{
webClient.Headers[HttpRequestHeader.Accept] = "application/octet-stream";
webClient.Headers[HttpRequestHeader.ContentType] = "text/bytes";
webClient.Encoding = System.Text.Encoding.ASCII;
byte[] result = webClient.UploadData(uri, data);
ret = Encoding.ASCII.GetString(result);
if (ret.Contains("\"ResultWebApi\":\"OK"))
{//In ret you can have JSON string
}
else
{
}
}
}
catch (Exception ex) { ret = ex.Message; }
return ret;
}
x

Answer 3

I've some examples in my Github repo. Just grab the classes there and give them a try. The API is really easy to use:
await new Request<T>()
.SetHttpMethod(HttpMethod.[Post|Put|Get|Delete].Method) //Obligatory
.SetEndpoint("http://www.yourserver.com/profilepic/") //Obligatory
.SetJsonPayload(someJsonObject) //Optional if you're using Get or Delete, Obligatory if you're using Put or Post
.OnSuccess((serverResponse) => {
//Optional action triggered when you have a succesful 200 response from the server
//serverResponse is of type T
})
.OnNoInternetConnection(() =>
{
// Optional action triggered when you try to make a request without internet connetion
})
.OnRequestStarted(() =>
{
// Optional action triggered always as soon as we start making the request i.e. very useful when
// We want to start an UI related action such as showing a ProgressBar or a Spinner.
})
.OnRequestCompleted(() =>
{
// Optional action triggered always when a request finishes, no matter if it finished successufully or
// It failed. It's useful for when you need to finish some UI related action such as hiding a ProgressBar or
// a Spinner.
})
.OnError((exception) =>
{
// Optional action triggered always when something went wrong it can be caused by a server-side error, for
// example a internal server error or for something in the callbacks, for example a NullPointerException.
})
.OnHttpError((httpErrorStatus) =>
{
// Optional action triggered when something when sending a request, for example, the server returned a internal
// server error, a bad request error, an unauthorize error, etc. The httpErrorStatus variable is the error code.
})
.OnBadRequest(() =>
{
// Optional action triggered when the server returned a bad request error.
})
.OnUnauthorize(() =>
{
// Optional action triggered when the server returned an unauthorize error.
})
.OnInternalServerError(() =>
{
// Optional action triggered when the server returned an internal server error.
})
//AND THERE'S A LOT MORE OF CALLBACKS THAT YOU CAN HOOK OF, CHECK THE REQUEST CLASS TO MORE INFO.
.Start();
And there's a couple of examples.

Answer 4

For all my Xamarin Forms app I use Tiny.RestClient.
It's easy to get it and easy to use it.
You have to download this nuget.
And after it just very easy to use it :
var client = new TinyRestClient(new HttpClient(), "http://MyAPI.com/api");
var cities = client.
GetRequest("City").
AddQueryParameter("id", 2).
AddQueryParameter("country", "France").
ExecuteAsync<City>> ();
Hopes that helps.