File upload control reactive forms

Question

Issue

I currently have a form that has a bunch of fields, one of them being a file upload field. They all form part of a FormGroup that is declared in my constructor. Now all the text controls I am able to access by using this.control.value except my file control. When I try to access the value of the form control for the file all I get is C:/fakepath/image.png.

Is there a way to access the actual file data so that I can upload it to my API?

Code

My FormControl declarations:

/**
 * Category of the product
 */
public category = new FormControl('', [
  Validators.required
]);

/**
 * Name of the product
 */
public name = new FormControl('', [
  Validators.required,
  Validators.minLength(3)
]);

/**
 * Description of the product
 */
public description = new FormControl('', [
  Validators.required
]);

/**
 * Price of the product
 */
public price = new FormControl('', [
  Validators.required
]);

/**
 * Image of the product
 */
public image = new FormControl('', [
  Validators.required
]);

My constructor for the page/component:

constructor(private api: ApiService,
  private formBuilder: FormBuilder) {

    this.productForm = formBuilder.group({
      category: this.category,
      name: this.name,
      description: this.description,
      price: this.price,
      image: this.image
    });
}

How I am currently trying to access the file

public async createProduct(): Promise<any> {
  console.log(this.image.value);
}

Angular doesn't support files in its forms. You will have to set it by hand (as far as I know, of course) — user4676340
– user4676340, Commented Mar 4, 2019 at 12:05
you can serialize this.productForm and add it into the FormData as a property and add the image as a seperate property. — Kunal Mukherjee
– Kunal Mukherjee, Commented Mar 4, 2019 at 12:06

Kunal Mukherjee · Accepted Answer · 2019-03-04 12:13:25Z

Step 1: HTML Template (file-upload.component.html)

Define simple input tag of type file. Add a function to (change)-event for handling choosing files.

<div class="form-group">
    <label for="file">Choose File</label>
    <input type="file"
           id="file"
           (change)="handleFileInput($event.target.files)">
</div>

Step 2: Upload Handling in TypeScript (in component file)

Define an default variable for selected file.

fileToUpload: File = null;

Create function which you use in (change)-event of your file input tag:

handleFileInput(files: FileList) {
    this.fileToUpload = files.item(0);
}

Step 3: File-Upload Service

By uploading a file via POST-method you should use FormData, because so you can add file to http request.

postFile(fileToUpload: File): Observable<boolean> {
    const endpoint = 'your-destination-url';
    const formData: FormData = new FormData();
    // Append image file to formdata as a seperate property
    formData.append('fileKey', fileToUpload, fileToUpload.name);

    // Append reactive form data too in a seperate property
    formData.append('productForm', JSON.stringify(this.productForm, null, 4));
    return this.httpClient
      .post(endpoint, formData, { headers: yourHeadersConfig })
      .map(() => { return true; })
      .catch((e) => this.handleError(e));
}

Vadim · Accepted Answer · 2019-03-04 12:37:44Z

Is there a way to access the actual file data so that I can upload it to my API?

You can access it in that way:

// template
<input
 type="file" (change)="onFileChanged($event)"
>

// component
onFileChanged(event) {
  // this.image will be updated each time the file
  // in input will be changed
  this.image = event.target.files[0];
  console.log(this.image);
}


createProduct(): Promise<Product> {
  console.log(this.image);
  const formData = new FormData();
  formData.append(
    'image',
    this.image
  );

  // add other fields to formData:
  formData.append("name", this.productForm.controls['name'].value);

  formData.append("description", this.productForm.controls['description'].value);

  const url = 'urlToApi';

  return this.http.post(url, formData)
    .toPromise()
    .then(response => {
      return response;
    })
    .catch(err => console.log(err));
}

Collectives™ on Stack Overflow

File upload control reactive forms

Issue

Code

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

Issue

Code

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related