Browser technology currently doesn’t support downloading a file directly from an Ajax request. The work around is to add a hidden form and submit it behind the scenes to get the browser to trigger the Save dialog.
I’m running a standard Flux implementation so I’m not sure what the exact Redux (Reducer) code should be, but the workflow I just created for a file download goes like this…
- I have a React component called
FileDownload
. All this component does is render a hidden form and then, insidecomponentDidMount
, immediately submit the form and call it’sonDownloadComplete
prop. - I have another React component, we’ll call it
Widget
, with a download button/icon (many actually… one for each item in a table).Widget
has corresponding action and store files.Widget
importsFileDownload
. Widget
has two methods related to the download:handleDownload
andhandleDownloadComplete
.Widget
store has a property calleddownloadPath
. It’s set tonull
by default. When it’s value is set tonull
, there is no file download in progress and theWidget
component does not render theFileDownload
component.- Clicking the button/icon in
Widget
calls thehandleDownload
method which triggers adownloadFile
action. ThedownloadFile
action does NOT make an Ajax request. It dispatches aDOWNLOAD_FILE
event to the store sending along with it thedownloadPath
for the file to download. The store saves thedownloadPath
and emits a change event. - Since there is now a
downloadPath
,Widget
will renderFileDownload
passing in the necessary props includingdownloadPath
as well as thehandleDownloadComplete
method as the value foronDownloadComplete
. - When
FileDownload
is rendered and the form is submitted withmethod="GET"
(POST should work too) andaction={downloadPath}
, the server response will now trigger the browser’s Save dialog for the target download file (tested in IE 9/10, latest Firefox and Chrome). - Immediately following the form submit,
onDownloadComplete
/handleDownloadComplete
is called. This triggers another action that dispatches aDOWNLOAD_FILE
event. However, this timedownloadPath
is set tonull
. The store saves thedownloadPath
asnull
and emits a change event. - Since there is no longer a
downloadPath
theFileDownload
component is not rendered inWidget
and the world is a happy place.
Widget.js – partial code only
import FileDownload from './FileDownload';
export default class Widget extends Component {
constructor(props) {
super(props);
this.state = widgetStore.getState().toJS();
}
handleDownload(data) {
widgetActions.downloadFile(data);
}
handleDownloadComplete() {
widgetActions.downloadFile();
}
render() {
const downloadPath = this.state.downloadPath;
return (
// button/icon with click bound to this.handleDownload goes here
{downloadPath &&
<FileDownload
actionPath={downloadPath}
onDownloadComplete={this.handleDownloadComplete}
/>
}
);
}
widgetActions.js – partial code only
export function downloadFile(data) {
let downloadPath = null;
if (data) {
downloadPath = `${apiResource}/${data.fileName}`;
}
appDispatcher.dispatch({
actionType: actionTypes.DOWNLOAD_FILE,
downloadPath
});
}
widgetStore.js – partial code only
let store = Map({
downloadPath: null,
isLoading: false,
// other store properties
});
class WidgetStore extends Store {
constructor() {
super();
this.dispatchToken = appDispatcher.register(action => {
switch (action.actionType) {
case actionTypes.DOWNLOAD_FILE:
store = store.merge({
downloadPath: action.downloadPath,
isLoading: !!action.downloadPath
});
this.emitChange();
break;
FileDownload.js
– complete, fully functional code ready for copy and paste
– React 0.14.7 with Babel 6.x [“es2015”, “react”, “stage-0”]
– form needs to be display: none
which is what the “hidden” className
is for
import React, {Component, PropTypes} from 'react';
import ReactDOM from 'react-dom';
function getFormInputs() {
const {queryParams} = this.props;
if (queryParams === undefined) {
return null;
}
return Object.keys(queryParams).map((name, index) => {
return (
<input
key={index}
name={name}
type="hidden"
value={queryParams[name]}
/>
);
});
}
export default class FileDownload extends Component {
static propTypes = {
actionPath: PropTypes.string.isRequired,
method: PropTypes.string,
onDownloadComplete: PropTypes.func.isRequired,
queryParams: PropTypes.object
};
static defaultProps = {
method: 'GET'
};
componentDidMount() {
ReactDOM.findDOMNode(this).submit();
this.props.onDownloadComplete();
}
render() {
const {actionPath, method} = this.props;
return (
<form
action={actionPath}
className="hidden"
method={method}
>
{getFormInputs.call(this)}
</form>
);
}
}