Embedding a user service in a user validator

Question

I am trying to create a custom Angular 2 form Validatorto check if a user exists in the database.

This is the code of my user form Validator

import { FormControl } from '@angular/forms';
import {API} from "../services/api";
import {ReflectiveInjector} from "@angular/core";

export class EmailValidator {

  constructor() {}

  static checkEmail(control: FormControl,): any {
    let injector = ReflectiveInjector.resolveAndCreate([API]);
    let api = injector.get(API);

    return api.checkUser(control.value).then(response => {
      response;
    });

  }

}

And this is my special service that is responsible for the request to the node api on the backend

import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/toPromise';

@Injectable()
export class API {
  private backendUrl = 'http://127.0.0.1:5000/api/register/';

  constructor(private http: Http) { }

  checkUser(email:string): Promise<any> {
    return this.http.get(this.backendUrl + email)
      .toPromise()
      .then(response => response.json())
      .catch(this.handleError);
  }

When I try to check the user, this is an error that is displayed

EXCEPTION: Error in ./TextInput class TextInput - inline template:0:0 caused by: No provider for Http! (API -> Http)

What am I doing wrong?

thank

Answer 1

@Injectable()
export class EmailValidator {

  constructor(private api:API) {}

  /* static */ checkEmail(control: FormControl,): any {
    return this.api.checkUser(control.value).then(response => {
      response;
    });
  }
}

Add it to @NgModule()or @Component()depending on which area you want it to be

providers: [EmailValidator]

Add it to the component in which you want to use it

export class MyComponent {
  constructor(private emailValidator:EmailValidator, fb:FormBuilder){}

  this myForm = fb.group({
    email: [], [this.emailValidator.checkEmail.bind(this.emailValidator)]
  });
}