title: How to send binary file multipart/form-data using post Angular?
body: <p>I have tried to send a binary file with additional fields using post method and multipart/form-data.</p>
  <pre><code>load() {
      const formData = new FormData();
      formData.append('file', this.data.binary);
      formData.append('reasons', this.form.get('reasons').value);
  
      const headers = new HttpHeaders({
          key: userKey,
      });
  
      const options = { headers: headers };
  
      this.http
          .post(`/api/Controller`, formData, options)
          .pipe(catchError(this.handleError))
          .subscribe(
              () =&gt; {
                  alert('Success');
              },
              (error) =&gt; {
                  alert(error.Message || 'Error');
              },
          );
  }
  </code></pre>
  <p>Where <code>this.data.binary</code> is:</p>
  <pre><code> try {
              const input = event.target as HTMLInputElement;
              const reader = new FileReader();
  
              reader.onload = () =&gt; {
                  this.data.binary = reader.result;
              };
              reader.readAsArrayBuffer(input.files[0]);
          } catch (e) {
              alert(e);
          }
  </code></pre>
  <p>In Chrome headers I see this data after submit:</p>
  <p><strong>FormData</strong></p>
  <pre><code>  file: [object ArrayBuffer]
    reasons: text
  </code></pre>
  <p>How to send file as binary correct?</p>
  <p>I have trird also this:</p>
  <pre><code>   formData.append('file', new Blob(this.data.binary));
  </code></pre>