Create XLSX file from file contents from server and save it-CodePudding

I got Node JS server which gets XLSX file contents from metabase:

app.get('/channels', async (req, res) => {
            // make request to metabase and take response as XLSX
            const queryRequestURL = `${api}/public/card/${cardId}/query/xlsx?parameters=${params}`;
                
        const result = got(queryRequestURL);
                
        res.setHeader('Content-Type', 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
        res.setHeader("Content-Disposition", "attachment; filename=file.xlsx");
                
        return res.send(res);

        });

It returns file contents like

So when i make request to server and receive response - it comes as file contents above. I need to download this data as ordinary excel file on browser side.

What i've tried:

// make request with typical fetch and get result to res variable.
const filename = 'file.xlsx';
const file = new File(res, filename ,{ type: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'});

// create link and click it virtually to download created file
var a = document.createElement('a');
a.href = window.URL.createObjectURL(file);
a.download = filename;
a.click();

But I'm getting the error:

Uncaught (in promise) TypeError: Failed to construct 'Blob': The provided value cannot be converted to a sequence.

I think that I'm doing something wrong and there is more simple way to download file.

CodePudding user response：

Without seeing how you're fetching, it's hard to know. But you should be able to use response.blob() to download the result.

fetch("${api}/channels}", {
  method: "GET",
})
  .then((response) => response.blob())
  .then((blob) => {
    var url = window.URL.createObjectURL(blob);
    var a = document.createElement("a");
    a.href = url;
    a.download = "file.xlsx";
    document.body.appendChild(a);
    a.click();
    a.remove();
  });

CodePudding user response：

As Joey Ciechanowicz mentioned, we should return response.buffer() from backend and work with its data as blob at frontend. I mean

NodeJS side (using Got):

const result = got(queryRequestURL, {
        headers: headers
    });

    return await result.buffer()

Frontend side (pure JavaScript):

// fetch data
const result = await fetch(api   path);
return result.blob();

// download file
const filename = 'export.xlsx';

var url = window.URL.createObjectURL(result);
var a = document.createElement('a');
a.href = url;
a.download = filename;
a.click();
a.remove();