node.jsblobfirebirdnode-firebird

Firebird jpeg blob field being returned as "[Function (anonymous)]" on node.js


I already saw a topic around here talking about the same problem, but the resolution doesn't apply to me cause because I am trying to open an image that has a variable number of bytes.

The code:

router.get('/foto', function (req, res) {
    const fdb = req.session.subdomain
    const product = req.query.product

    firebird.attach(conn(fdb), function (err, conn) {

        if (err)
            throw err;

        conn.query('SELECT photo FROM product WHERE product = ?', product,
        function (err, result) {
            if (err) {
                res.status(200).send(err);
            } else {
                console.log(result[0].PHOTO)
                res.json(result[0].PHOTO)
                conn.detach();
            }
        })
    })
})

It returns null if the product doesn't have a photo, and if it has returns:

[Function (anonymous)]

I need to know how to read it as blob to convert to base64, cause if I try to do this with "[Function (anonymous)]", the conversion of blob to base64 gives me "Error: Invalid BLOB handle".

The function to convert blob:

function readBlob(blob) {
    if (blob == null) {
        return null
    }
    blob(function (err, name, e) {
        let buffers = [];
        e.on('data', function (chunk) {
            buffers.push(chunk);
        });
        e.on('end', function () {
            let buffer = Buffer.concat(buffers);
            console.log(buffer)
            return buffer.toString('base64')
        });
    });
}

I'm using Node.js, Express, and the npm module node-firebird.


Solution

  • I found the answer in this topic of C#. The problem is in my query, in Firebird I have to specify the format of data I want it to return, so I changed my select to this:

    SELECT cast(photo as BLOB SUB_TYPE BINARY) photo FROM product WHERE product = ?
    

    and then when I used my "readBlob" function it worked.