Fetch API to force download file

问题

I'm calling an API to download excel file from the server using the fetch API but it didn't force the browser to download, below is my header response:

HTTP/1.1 200 OK Content-Length: 168667 
Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet 
Server: Microsoft-IIS/8.5 
Content-Disposition: attachment; filename=test.xlsx 
Access-Control-Allow-Origin: http://localhost:9000 
Access-Control-Allow-Credentials: true 
Access-Control-Request-Method: POST,GET,PUT,DELETE,OPTIONS 
Access-Control-Allow-Headers: X-Requested-With,Accept,Content-Type,Origin 
Persistent-Auth: true 
X-Powered-By: ASP.NET 
Date: Wed, 24 May 2017 20:18:04 GMT

Below my code that I'm using to call the API :

this.httpClient.fetch(url, {
    method: 'POST',
    body: JSON.stringify(object),
    headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json'
    }
})

回答1:

The browser won't show the usual interaction for the download (display Save As... dialog, etc.), only if you navigate to that resource. It is easier to show the difference with an example:

window.location='http://mycompany.com/'
Load http://mycompany.com/ via XHR/Fetch in the background.

In 1., the browser will load the page and display its content. In 2., the browser will load the raw data and return it to you, but you have to display it yourself.

You have to do something similar with files. You have the raw data, but you have to "display" it yourself. To do this, you need to create an object-URL for your downloaded file and navigate to it:

this.httpClient
    .fetch(url, {method, body, headers})
    .then(response => response.blob())
    .then(blob => URL.createObjectURL(blob))
    .then(url => {
        window.open(url, '_blank');
        URL.revokeObjectURL(url);
    });

This fetches the response, reads it as a blob, creates an objectURL, opens it (in a new tab), then revokes the URL.

More about object-URLs: https://developer.mozilla.org/en-US/docs/Web/API/URL/createObjectURL

回答2:

There are some handy libraries and to solve an issue that I had with CSV/text download I used FileSaver.

Example:

var saveAs = require('file-saver');

fetch('/download/urf/file', {
  headers: {
    'Content-Type': 'text/csv'
  },
  responseType: 'blob'
}).then(response => response.blob())
  .then(blob => saveAs(blob, 'test.csv'));

There is also download.js lib as explained here in this question.

回答3:

I found another way to download and it will work on IE by using

https://www.npmjs.com/package/downloadjs

来源：https://stackoverflow.com/questions/44168090/fetch-api-to-force-download-file

标签

download

aurelia

fetch-api