title: Angular 6 - Error using http.get responseType: ResponseContentType.Blob
body: <p>I'd like to make an observable like this in (angular 5).
  How can I declare <code>responseType</code> in Angular 6?</p>
  
  <p><strong>The Angular 5 code:</strong></p>
  
  <pre><code>public ExportSomeThing(
          ano: number
      ): Observable&lt;IDownloadArquivo&gt; {
          let q = this.http
              .get(this.apiUrl + ano + '/pordia/excel', {
                  responseType: ResponseContentType.Blob  // &lt;&lt;&lt;-- This code
              }).map((res) =&gt; { 
  </code></pre>
  
  <p><strong>My angular 6 code:</strong></p>
  
  <pre><code>public MyExport(
      ano: number
    ): Observable&lt;IXpto&gt; {
      let q = this.http
        .get( this.api_rul + ano + '/some_path/', {
          responseType: "ResponseContentType.Blob"  // &lt;&lt;&lt;--- error here !!!
        }).map((res) =&gt; {
  </code></pre>
  
  <p><strong>The  error is:</strong></p>
  
  <pre><code>[ts]
  Argument of type '{ responseType: "ResponseContentType.Blob"; }' is not assignable to parameter of type '{ headers?: HttpHeaders | { [header: string]: string | string[]; }; observe?: "body"; params?: HttpParams | { [param: string]: string | string[]; }; reportProgress?: boolean; responseType?: "json"; withCredentials?: boolean; }'.
    Types of property 'responseType' are incompatible.
      Type '"ResponseContentType.Blob"' is not assignable to type '"json"'.
  </code></pre>
  
  <p><strong>How can I make my <code>http.get</code> similar in Angular 6?</strong></p>
  
  <p>I'm trying to download Excel method!</p>