Form validation with the server

Question

I have a form that I would like to perform http validation by checking if an email exists but it returns an error. This is my form:

On the form component

Answer 1

https://angular.io/docs/ts/latest/api/forms/index/FormBuilder-class.html

async validators is the 3rd parameter

email:['', [Validators.required], [
  this._validationService.emailExistsValidator.bind(this)
]]