c# - Exception from MVC API to MVC site gives error -

i have created mvc (4) web api works fine. has simple login-method throws exception when user cannot found.

besides api created simple website calls api httpclient:

public t executepost<t>(string apiurl, ienumerable<keyvaluepair<string, string>> postdata) {     httpcontent content = null;      if (postdata != null)         content = new formurlencodedcontent(postdata);      var = _client.postasync(apiurl, content).continuewith(httpresponsemessage =>          jsonconvert.deserializeobject<t>(httpresponsemessage.result.content.readasstringasync().result)     );     return a.result; } 

you can call method

executepost<user>("url_to_controller_action_api", list_with_keys_and_values_to_post) 

when method calls api postdata-fiels username , password (both correct , known system) object called user returned... works charm. when call method wrong username and/or password, api throws exception (user not found), method executepost throws exception aswell , web page shows nice, yellow-isch, red-letter page errors normal user not understand. reason easy: data sent api not same data can put in object user.

so, deserialize exception, api, in object called error , return controller of mvc website, can put error "user not found" on page correct design of site.

what best way this? try-catch in actions? doesn't feel right me... suggestions more welcome.

most things found api-side stuff, want fetch , handle exception on site-side.

thanks in advance

on web api when detect invalid login, make sure httpresponseexception gets thrown status code of 401 (httpstatuscode.unauthorized).

//login failed: var resp = new httpresponsemessage(httpstatuscode.unauthorized)                 {                     content = new stringcontent("invalid username or password")                 };             throw new httpresponseexception(resp); 

in calling code, can first check if httpresponsemessage.statuscode==httpstatuscode.ok before attempt deserialise response user.

var = _client.postasync(apiurl, content).continuewith(httpresponsemessage => { if (httpresponsemessage.status!=httpstatus.ok) {      string errormessage = httpresponsemessage.result.content.readasstringasync();      //and whatever want error message here } else {   try     {        var user = jsonconvert.deserializeobject<t>(httpresponsemessage.result.content.readasstringasync().result);     }     catch(exception ex)     {         //honest goodness unrecoverable failure on webapi.         //all can here fail gracefully caller.     } }//endif (status ok) }//end anonymous function ); 

if it's not 200 can execute second check see if it's 401 (and have specific handling invalid login) or more general 500 (something went wrong on server), etc, , actual error message of exception ("invalid username or password") send client:

var errormessage = httpresponsemessage.content.readasstringasync().result;

finally, if 200 should still try...catch deserialisation operation can gracefully handle issues returned data, if whatever reason data can't turned user object.