title: TypeError: Cannot create property 'validator' on string 'abc@gmail.com' at setUpControl
body: <p>I face issue in <code>formGroup</code>. First Based on URL I take some value and call to API for retrieve particular user-data for pre-field text.</p>
  
  <p>register.html</p>
  
  <pre><code>&lt;form [formGroup]="form" (ngSubmit)="onSubmit(form.value)" class="form-horizontal"&gt;
      &lt;div class="form-group row"&gt;
          &lt;label for="inputEmail3" class="col-sm-4 "&gt;Username&lt;/label&gt;
          &lt;div class="col-sm-8"&gt;
              &lt;input [formControl]="email" type="text" class="form-control" id="inputEmail3" placeholder="Email Address" [readonly]="isReadOnly"&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>register.component.ts</p>
  
  <pre><code>import { Component } from '@angular/core';
  import { FormGroup, AbstractControl, FormBuilder, Validators } from '@angular/forms';
  import { Router, ActivatedRoute } from '@angular/router';
  import { EmailValidator, EqualPasswordsValidator } from '../../theme/validators';
  
  @Component({
    selector: 'register',
    templateUrl: './register.html',
  })
  export class Register {
    public form: FormGroup;
    public email: AbstractControl;
    public username: string;
  
    constructor(private registerService: RegisterService, fb: FormBuilder, private router: Router, private route: ActivatedRoute) {
      this.form = fb.group({
        'email': ['', Validators.compose([Validators.required])]
        .... etc..
      });
  
      this.email = this.form.controls['email'];
  
      this.registerService.getUser({ userId: "asdasd2123da2das" }).subscribe(posts =&gt; {
        if (posts) {
            var userObj = posts.json();
            console.log("userObj : ", userObj.data);
            if (userObj.data &amp;&amp; userObj.data[0].email) {
              this.email = this.username = userObj.data[0].email;  // ouput : abc@gmail.com
              this.isReadOnly = true;
              this.router.navigateByUrl('/register');
            } else {
              alert("You are Not Autorize to access this Page");
              this.router.navigateByUrl('/login');
            }
          }
      });
  
    }
  }
  </code></pre>
  
  <p>Error Details :</p>
  
  <pre class="lang-none prettyprint-override"><code>TypeError: Cannot create property 'validator' on string 'abc@gmail.com'
      at setUpControl (http://localhost:3004/vendor.dll.js:9739:23)
      at FormControlDirective.ngOnChanges (http://localhost:3004/vendor.dll.js:44196:89)
      at Wrapper_FormControlDirective.ngDoCheck (/ReactiveFormsModule/FormControlDirective/wrapper.ngfactory.js:50:18)
  </code></pre>