如何在 MySQL 中将 multer 文件上传为 blob？

Question

I'm trying to store a file uploaded into a nodejs server into a mysql database. The file is uploaded and processed using a Multer middleware, thus storing all the file information in req.files . I believe, correct me if I am mistaken, that this data/parameters must be somehow converted to a blob format yet I do not know how to do so effectively. How could this be done in order to upload it into a MySQL database?

I am using the latest version of XAMPP with a MySQL InnoDB tables. The file parameters/data generated by Multer are shown in the code snippet. I've attempted converting the entire file, that is req.files[0] , into a blob yet the blobs stored in the MySQL database are identical in size despite using different files.

[ { fieldname: 'files',
    originalname: 'Event Information 2018-1_2084.pdf',
    encoding: '7bit',
    mimetype: 'application/pdf',
    destination:
     '/home/millana/Desktop/Brandink/Code/server/middleware/../designs/',
    filename: 'Event Information 2018-1_2084_1559843587360.pdf',
    path:
     '/home/millana/Desktop/Brandink/Code/server/designs/Event Information 2018-1_2084_1559843587360.pdf',
    size: 1125992 } ]

Below is shown the restAPI called to execute the query on an already existing table Designs and database.

router.post('/order', upload.array('files'), (req, res) => {
    console.log(req.files[0].buffer);

    const order_id = 1;
    const position = 'front';

    const sql = `INSERT INTO Designs VALUES ('${order_id}', '${position}', '${req.files[0].filename}', '${req.files[0].mimetype}', '${req.files[0].buffer}')`;


    db.query(sql, (err, result) => {
        if(err) res.status(400).send(err);
        res.status(200).send(result);
    });

});

The middleware function includes:

const storage = multer.diskStorage({
    destination: function(req, file, cb) {
        cb(null,  __dirname + '/../designs/');
    },
    filename: function (req, file, cb) {
        let format = '';

        if      ( file.mimetype === 'image/jpeg' )      format = '.jpg';
        else if ( file.mimetype === 'image/png' )       format = '.png';
        else if ( file.mimetype === 'application/pdf' ) format = '.pdf';


        let fileName = _.split(file.originalname, '.')[0] + '_' + Date.now() + format;
        cb(null, fileName);
    }
});

const upload = multer({
    storage: storage,
    limits: {
        fileSize: MAX_SIZE
    },
});

I expect the blob size to vary from one file to another proportionally with their file size. However, the size for all files uploaded is of 9 bytes while the buffers are identical, indicating that the same object/file is being stored. How can I store each different file accordingly?

Answer 1

How about using fileFilter? You can manage the quality of file, or size etc. https://github.com/expressjs/multer

As you see in links or your knowledge, multer has some options like fileFilter or limits. fileFilter, is similar to your function, to select file type. limits,

fileSize : { 5 * 1024 * 1024 }

And I've heard that storing files like image is to convert a binary file in a buffer.

if you console.log(img file), you can see the output such as Binary { _bsontype: 'Binary', sub_type: 0, position: 260547, buffer: } }

then change array Buffer to base64, string. the result is,
data : image/jpeg;base64, v9emlk3SGF45fg...

It is different from 'filename or originalName',

so it could be saved as a different one.