Resilient Postgres listen client
npm install pg-ears> Resilient Postgres listen client
This project is not in any production use by the author. There has also been
very little community engagement on the module that would motivate the
extensive time investment to make this module as good as pg-listen. Given
that module has more usage and is actively maintained I would strongly
recommend using that instead.
- LISTEN leaks:
Upon disconnect and reconnect LISTEN statements accumulate
``sh`
$ npm install --save pg-ears
pg-ears exports a single function takes the same options as a new
node-postgres new Client(opts) with a couple additions and returns an objectlisten
containing the methods and notify
- options (Object - required) Options for node-postgres connection plus the
following:
- checkInterval (Number (ms) - optional - default: 30000 [30 sec.])
- maxAttempts (Number - optional - default: 60) Multiplier of
checkInterval - number of attempts before giving up on reconnect
listen(channel, callback)
- channel (String - required)
- callback (Function - required) will be called every time a message is
received with as arguments OR with an error when the PG client
encounters an error
notify(channel, payload, callback)
- channel (Object - required)
- payload (Object | Array | String - required)
- callback (Object - optional) will be called with error if unable to send
OR when an error occurs on the PG client
`js`
const options = {
user: 'foo', //env var: PGUSER
database: 'my_db', //env var: PGDATABASE
password: 'secret', //env var: PGPASSWORD
host: 'localhost', // Server hosting the postgres database
port: 5432 //env var: PGPORT
}
const pgEars = require('pg-ears')(options)
pgEars.listen('mychannel', (err, data) => {
if (err) return console.error(err)
console.log(data)
})
pgEars.notify('mychannel', {key: 'value'}, (err) => {
if (err) console.error(err)
})
:warning: Channel names in postgresql are identifiers`, just like the name of a
table or a column.
Please refer to the offical postgresql documentation about valid identifiers.
node-postgres does not currently allows channel names to be parameterized to
avoid sql-injection attacks.
See node-postgres issue #1258
for details.
**pg-ears performs no validation or sanitation on the channel names and they are
inserted into the sql queries as-is.**
On the other hand, payloads of your notifications are json encoded and decoded
automatically by pg-ears and passed using safe parameterized queries.
MIT © Andrew Carpenter