knex.js pipe to express

Question

i have a problem in knex.js and express, code like below:

userRouter.get('/:userId', function (req, res) {
  DB('users').where({
    id: req.params.userId
  }).first('name').pipe(res);
});

as knex.js doc wrote: there is a stream interface for knex.js query.

but i can not pipe the result to express(node http api) response.

the code above does not work.

there is a "TypeError":

TypeError: first argument must be a string or Buffer

what went wrong?

Answer 1

Create a stream and pipe it first to JSONStream and finally pipe it to your response object

var knex = require('knex')({
  client: 'mysql',
  connection: {
    host     : '...',
    user     : '...',
    password : '...',
    database : '...'
  }
});
var JSONStream = require('JSONStream');
var express = require('express');
var app = express();

app.get('/', function (req, res) {
    var sql = knex.select('*').from('table').limit(3);
    res.set('Content-Type', 'application/json');
    sql.stream().pipe(JSONStream.stringify()).pipe(res);
});

var server = app.listen(3000, function () {
  var host = server.address().address;
  var port = server.address().port;

  console.log('Example app listening at http://%s:%s', host, port);
});