angular - Angular2 username or email taken async validation -

i need implement async validation github api. hope me.

        export class usernamevalidator {                static usernametaken(control: formcontrol): promise<validationresult> {                 return new promise((resolve, reject) => {                     settimeout(() => {                                   //how can use github api this:                          // if (control.value === "this._http.get('http://api.github.com/users/'+this.username)")) {                         if (control.value === "david") {                             console.log('username taken')                             resolve({"usernametaken": true})                         } else {                              resolve(null);                         };                                     }, 1000);                 });              }         } 

thank you.

this implemented within reactive form, should modifiable solution form driven method.

the validator given service actual via api (a 404 returned if given user not exist):

export function usernametaken(httpservice: httpservice) {     return control => new promise((resolve, reject) => {       console.log("in validator");             //how can use github api this:              httpservice.lookupuser(control.value).subscribe(data => {               console.log(data);               if(data.id) {                 resolve({ usernametaken : true})               } else {                 resolve(null);               }             }, (err) => {               console.log("in error"+ err);               if(err !== "404 - not found") {                 resolve({ usernametaken : true});             } else {               resolve(null);             }               });     }); } 

the service looks this:

 @injectable()  export class httpservice {    constructor(private http: http) {}     lookupuser(username: string): observable<any> {         return this.http.get("https://api.github.com/users/" + username)             .map(this.extractdata)             .catch(this.handleerror) observable<any>;     };  <...>  } 

and inject in service , apply validator (third spot in array asyncvalidators:

constructor(private fb: formbuilder, private httpservice: httpservice) {     this.name = 'angular2',     this.form = this.fb.group({       username: ['', validators.required, usernametaken(this.httpservice)]     }); 

with actual input looking pretty normal:

<input type="text" placeholder="username" formcontrolname="username"/> 

here's plunker demonstrating usage of async validator: http://plnkr.co/edit/19lp0e9x6l4kpyx0org0?p=preview