React/Redux download file - ajax

Question

I need to download a file from the server when a button is clicked.
I created a MaterialUI button and on its onclick callback i call an action of the container component connected.
The action is asynchronous and does an ajax POST:
export const onXlsxClick = () => dispatch => {
const urlParams = {
filters: {
aggregation: 'macro_area',
chart_resolution: '1_hour',
chart_from: '1478080363',
chart_to: '1477993963'
},
labels: ['PROVA1', 'PROVA2'],
series: [
{
label: null,
timestamp: 1478080363,
values: [123, 345]
},
{
label: null,
timestamp: 1477993963,
values: [153, 3435]
}
]
};
return $.ajax({
url:'/rest/export/chart/xlsx',
type: 'POST',
dataType: 'application/json',
contentType: 'application/json',
data: JSON.stringify(urlParams)
})
.done(data => {
console.log('success');
})
.fail(error => {
console.log(error);
});
};
The server receive the request and handle it correctly through this REST service:
#POST
#Path("xlsx")
#Produces("application/vnd.ms-excel")
public Response getXlsx(ChartExportRequest request) {
ResponseBuilder responseBuilder;
ChartExportRequestDTO reqDto = null;
try {
reqDto = parseDTO(request);
checkRequestDTO(reqDto);
ExportDTO dto = getXlsxProvider().create(reqDto);
responseBuilder = Response.ok(dto.getFile())
.header("Content-disposition", "attachment;filename=" + dto.getFileName());
}
catch(Exception e) {
logger.error("Error providing export xlsx for tab RIGEDI with request [" + (reqDto != null ? reqDto.toString() : null) + "]", e);
responseBuilder = Response.serverError().entity(e.getMessage());
}
return responseBuilder.build();
}
The problem is that the response arrives correctly to the client but then nothing happens: I am expecting that the browser shows the download dialog (example: in chrome I expect the bottom bar of downloads to appear with my file).
What am I doing wrong?

Answer 1

AS per Nate's answer here, the response of Ajax request is not recognised by a browser as a file. It will behave in the same way for all Ajax responses.
You need to trigger the download popup manually.
In my implementation, I used filesaverjs to trigger the download popup, once I have received the API response in reducer.
Since FileSaver uses blob for saving the file, I am sending the response from server as a blob, converting it into string array buffer and then using it to save my file. This approach was described in
Please find the sample code below for the reducer :
(using reducer for state modification, as per Redux)
reducer.js
let fileSaver = require("file-saver");
export default function projectReducer(state = {}, action)
{
let project;
switch (action.type) {
case GET_PROJECT_SUCCESS :
project = Object.assign(action.response.data);
return project;
case EXPORT_AND_DOWNLOAD_DATA_SUCCESS :
let data = s2ab(action.response.data);
fileSaver.saveAs(new Blob([data], {type: "application/octet-stream"}), "test.xlsx");
return state;
}
return state;
}
function s2ab(s) {
var buf = new ArrayBuffer(s.length);
var view = new Uint8Array(buf);
for (var i = 0; i != s.length; ++i) {
view[i] = s.charCodeAt(i) & 0xFF;
}
return buf;
}