title: Angular 5: Module not found: Error: Can't resolve '@angular/forms/src/validators'
body: <p>I am trying to create a custom validator using directive but getting below error.</p>
  
  <pre><code>ERROR in ./src/app/CustomValidators/white-space-validator.directive.ts
  Module not found: Error: Can't resolve '@angular/forms/src/validators' in 'D:\Angular\Admin\src\app\CustomValidators'
  resolve '@angular/forms/src/validators' in 'D:\Angular\Admin\src\app\CustomValidators'
    Parsed request is a module
    using description file: D:\Angular\Admin\package.json (relative path: ./src/app/CustomValidators)
      Field 'browser' doesn't contain a valid alias configuration
    after using description file: D:\Angular\Admin\package.json (relative path: ./src/app/CustomValidators)
      resolve as module.....
  </code></pre>
  
  <p>Code in directive file:</p>
  
  <pre><code>import { Directive } from '@angular/core';
  import { ValidatorFn, Validator } from '@angular/forms/src/directives/validators';
  import { AbstractControl, FormControl } from '@angular/forms/src/model';
  import { NG_VALIDATORS } from '@angular/forms/src/validators';
  
  @Directive({
    selector: '[whiteSpace][ngModel]',
    providers: [
      { provide: NG_VALIDATORS, useExisting: WhiteSpaceValidatorDirective, multi: true }
    ]
  })
  
  export class WhiteSpaceValidatorDirective  {
    validator : ValidatorFn;
  
    constructor() { 
      this.validator = checkWhiteSpaces();
    }
  
    validate(c: FormControl){
      return this.validator(c);
    }
  }
  
  function checkWhiteSpaces(): ValidatorFn {
    return (c: AbstractControl) =&gt; {
      let isValid = c.value.trim().length &gt; 0 ? true : false;
      if (isValid) {
        return null;
      }
      else {
        return {
          whiteSpace: { valid: false }
        }
      }
    }
  }
  </code></pre>
  
  <p>Versions of Package I am using:</p>
  
  <blockquote>
    <ul>
    <li>Angular CLI: 1.5.5 Node: 8.2.1 OS: win32 x64 Angular: 5.1.2 ...    animations, common, compiler, compiler-cli, core, forms ... http,<br>
    language-service, platform-browser ... platform-browser-dynamic,<br>
    router
       @angular/cli: 1.5.5 @angular-devkit/build-optimizer: 0.0.36    @angular-devkit/core: 0.0.22 @angular-devkit/schematics: 0.0.42<br>
    @ngtools/json-schema: 1.1.0 @ngtools/webpack: 1.8.5<br>
    @schematics/angular: 0.1.11 @schematics/schematics: 0.0.11<br>
    typescript: 2.4.2 webpack: 3.8.1</li>
    </ul>
  </blockquote>
  
  <p>Any help ?</p>