Koa middleware to get you a Postgres client on the way down the middlewares, and release it on the way back up the middlewares.

This extends Koa by adding a this.pg object to it. This contains the this.pg.client and this.pg.done. You should use this.pg.db.client to yield to the .query_() method (from co-pg) but you should not call this.pg.db.done() since that is used internally by koa-pg when going back up the middlewares.

var koa = require('koa')
var koaPg = require('koa-pg')

var app = koa()

app.use(koaPg('postgres://user:password@localhost:5432/database'))

app.use(function *(next) {
    // Here we have access to this.pg.db.client which is client returned from pg.connect().
    var result = yield this.pg.db.client.query_('SELECT now()')
    console.log('result:', result)

    this.body = result.rows[0].now.toISOString()
})

app.listen(3000)

• 'name' : default -> 'db'

This is the name you want to use for this database. The default is db which means the client is at this.pg.db.client. If you only have one database connection you may want to just leave this as the default. See below if you require two or more database connections (such as master or slave).

app.use(koaPg({
    name   : 'master',
    conStr : 'postgres://user:password@localhost:5432/database'
}))

app.use(function *(next) {
    var result = yield this.pg.master.client.query_('SELECT now()')
    this.body = result.rows[0].now.toISOString()
})

When using only one database connection you can use the default db name, but if you need more than one connection you must name at least one or other (or both) to something different. Let's say you have a master and a slave and you require a client at all times (in reality you'd probably just connect to one or the other depending on what operations you are doing).

app.use(koaPg({
    name   : 'master',
    conStr : 'postgres://user:password@masterhost:5432/database'
}))

app.use(koaPg({
    name   : 'slave',
    conStr : 'postgres://user:password@slavehost:5432/database'
}))

// a write query
app.use(function *(next) {
    var result = yield this.pg.master.client.query_('SELECT now()')
    // ...
})

// a read query
app.use(function *(next) {
    var result = yield this.pg.slave.client.query_('SELECT now()')
    // ...
})

Written by Andrew Chilton - Blog - Twitter.

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