Angular File Upload

Here is a working example for file upload to api:

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 (file-upload.component.ts)

Define a default variable for selected file.

fileToUpload: File | null = null;

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

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

If you want to handle multifile selection, than you can iterate through this files array.

Now create file upload function by calling you file-upload.service:

uploadFileToActivity() {
    this.fileUploadService.postFile(this.fileToUpload).subscribe(data => {
      // do something, if upload success
      }, error => {
        console.log(error);
      });
  }

Step 3: File-Upload Service (file-upload.service.ts)

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();
    formData.append('fileKey', fileToUpload, fileToUpload.name);
    return this.httpClient
      .post(endpoint, formData, { headers: yourHeadersConfig })
      .map(() => { return true; })
      .catch((e) => this.handleError(e));
}

So, This is very simple working example, which I use everyday in my work.