.net - Need some advice about the correct way to write own httpclient interface -

i want create wpf application connect web api server. i'm newbie in wpf. more worse,even in .net.

actually, things work, follow http://www.asp.net/web-api/overview/web-api-clients/calling-a-web-api-from-a-wpf-application.

after more search,i found totally work on wrong way(winform way).and seems should use mvvm style communites said. decide rewrite code.

i use prism create module, , bind name , password viewmodel class. can name , password textbox.

first, failed create httpclient instance every viewmodel use. below problem links

hot register constructed instance in unity?

so deicide write this. first create interface.

public interface idata {     ienumerable<device> getdevicesbyuser(user user);     ienumerable<user> getusers();     currentuser getcurrentuserinfo(); } 

and implement interface

public class httpservice : idata {     httpclient client = new httpclient();     public httpservice()     {         client.baseaddress = new uri("https://localhost:3721");         client.defaultrequestheaders.accept.add(new mediatypewithqualityheadervalue("application/json"));     }      public ienumerable<device> getdevicesbyuser(user user)     {         throw new notimplementedexception();     }      public ienumerable<user> getusers()     {         throw new notimplementedexception();     }      public currentuser getcurrentuserinfo()     {         throw new notimplementedexception();     } } 

later, can register instance in unity, , can use in every viewmodel.but situation can't go further. use 2 method,but neither can works. need advice correct way.

the fisrt way. write async methods each interface method.

public currentuser getcurrentuserinfo()     {       return getcurrentuserinfofromserver();     }  private async void getcurrentuserinfofromserver()     {         try         {             var response = await client.getasync("api/user");             response.ensuresuccessstatuscode();              var currentuser = await response.content.readasasync<currentuser>();         }         catch (newtonsoft.json.jsonexception jex)         {             messagebox.show(jex.message);         }         catch (httprequestexception ex)         {             messagebox.show(ex.message);         }                 {          }     } 

but seems async can not return type other void , task. , seems weird. try write request 1 method.

private async void getdata(string requesturi)     {         try         {             var response = await client.getasync("api/user"+requesturi);             response.ensuresuccessstatuscode();             var ? = await response.content.readasasync<?>();         }         catch (newtonsoft.json.jsonexception jex)         {             messagebox.show(jex.message);         }         catch (httprequestexception ex)         {             messagebox.show(ex.message);         }                 {          }     } 

this codes still have same problem first one. can not return type other void , task, , problem how data dynamic?

async methods should return task or task<t>, because that's being asynchronous means: method returns immediately, hasn't completed yet. so, result, await returned task. so, method this:

private async task<currentuser> getcurrentuserinfofromserverasync() {     try     {         var response = await client.getasync("api/user");         response.ensuresuccessstatuscode();          var currentuser = await response.content.readasasync<currentuser>();         return currentuser; // sets result of returned task     }     catch (newtonsoft.json.jsonexception jex)     {         messagebox.show(jex.message);     }     catch (httprequestexception ex)     {         messagebox.show(ex.message);     } } 

this means method calls getcurrentuserinfofromserverasync() needs async, , method that, etc., way top.

also, it's practice separate concerns: httpservice should not show messabeboxes , instead let exceptions propagate out of method. should leave dealing ui higher layers.