将缓冲区从ReadStream更改为实际文件

将缓冲区从ReadStream更改为实际文件

好的，这挽救了我的生命：https :
//youtu.be/pXHOF4GWuZQ。这是最终代码：

downloadFile(file_id) {    return new Promise((resolve, reject) => {        var mongoose = require('mongoose');        var Grid = require('gridfs-stream');        var fs = require('fs');        mongoose.connect(config.db, {useNewUrlParser: true},).catch(e => console.log(e));        var conn = mongoose.connection;        Grid.mongo = mongoose.mongo;        var gfs = Grid(conn.db);        console.log('downloadfile', file_id);        var read_stream = gfs.createReadStream({_id: file_id});        let file = [];        read_stream.on('data', function (chunk) { file.push(chunk);        });        read_stream.on('error', e => { console.log(e); reject(e);        });        return read_stream.on('end', function () { file = Buffer.concat(file); const img = `data:image/png;base64,${Buffer(file).toString('base64')}`; resolve(img);        });    });}