GridFS + NodeJS 从 mongoDB 检索图像

Question

我有以下来自 mongoDB 的带有图像的 JSON，但我不知道如何显示它：

fs.chunks:

{
        "_id" : ObjectId("542e684a8a1cec178a172673"),
        "n" : 1,
        "data" : BinData(0,"2N6DSSfbCN/LLacNDYrJUQDEZgimMUwFpQGoJP0RU19Bi4PM82DjrUnKhE/P9v7P8ZveD1oDpFBM0iml9NE3WQmAvYFoG+nhD73Jm4N9b4LpylaAN5Ef+gVdgGSTAfSUwOikXoVick5pSQCkRmTCU5NT9VVfjHdAx74/ZhFRj+TIRjzlAhzkACBElzgMwGCo7tX+FYrpQLJ5KRmXiwFFwsNtHHzXiK1eu+CG1FumhGpA/qdG8CdDgD1xUHEcerMGO/eLGR9ML7ni/VjXxWzqp2j5DG2/WuKNv7xd3Kz/vr0MctJhuaBIl35YrKhdLnzqDa0uDa6bm4jz+eNyAI2hQbayGo4kVPFe8W7wFpY7qfBvnB9kbocxfZSdADDUNwYaydpT8lIcKEN9XfQJOYZvHp0El"),
        "files_id" : ObjectId("542e684a8a1cec178a172671")
}

fs.files:

{
        "_id" : ObjectId("542e65378axdeckhb0"),
        "uploadDate" : ISODate("2012-11-01"),
        "length" : 15673,
        "chunkSize" : 33222,
        "md5" : "f66e6654854a28e3672cfhds334d223b55a1"
}

需要把“数据”变成真实的图像来展示。

我正在使用 nodeJS，但我找不到使用 GridFS 从 mongoDB 检索图像的好教程。

感谢您的帮助！

Answer 1

对不起，这个答案太晚了，但我很惊讶还没有人回答。无论如何，假设您正在运行 Express，以下代码将下载该文件。您需要将 gfs.findOne() 函数包装到 API 调用中。

const Grid = require('gridfs-stream');
const mime = require('mime');
const mongoose = require('mongoose');

// connect to the db, fill in the username/password/host/port/dbName.
// Ideally the connection is set up before the main part of the app runs.
const path = 'mongodb://username:password@host:port/dbName';
const dbConnection = mongoose.createConnection(path);

const gfs = new Grid(dbConnection.db);

// then once you get the id of the file you want:
gfs.findOne({
    _id: id
}, (err, file) => {
    if (err) {
        // report the error
    } else {
        // detect the content type and set the appropriate response headers.
        let mimeType = file.contentType;
        if (!mimeType) {
            mimeType = mime.lookup(file.filename);
        }
        res.set({
            'Content-Type': mimeType,
            'Content-Disposition': 'attachment; filename=' + file.filename
        });

        const readStream = gfs.createReadStream({
            _id: id
        });
        readStream.on('error', err => {
            // report stream error
        });
        // the response will be the file itself.
        readStream.pipe(res);
    }
});