gem-hunter
Language: Elixir
Transforms notifications from the Postgres LISTEN/NOTIFY mechanism into callback execution
Boltun simplifies handling of the LISTEN/NOTIFY mechanism offered by Postgres. Basically you will just need to define which callback(s) should be called on a specific notification and that's it
Add Boltun as a dependency in your mix.exs file.
defp deps do [{:boltun, "~> 1.0.2"}] end
After you are done, run mix deps.get in your shell to fetch the dependencies.
Defining a listener is trivial. See the example below
defmodule TestListener do use Boltun, otp_app: :my_app listen do channel "my_channel", :my_callback channel "my_channel", :my_other_callback channel "my_other_channel", :my_other_callback end def my_callback(channel, payload) do IO.puts channel IO.puts payload end ... end
The channel is a concept defined by Postgres. On the SQL side you will have something like NOTIFY my_channel, 'my payload' happening, for example, in a trigger which will cause your callbacks TestListener.my_callback and TestListener.my_other_callback to be called. The callbacks will be invoked synchronously in the order they were declared in the listen block.
Defining a listener is not enough to use it. It should be started with TestListener.start_link. You can do this, for example, in a supervisor.
The listener also needs the connection parameters to establish a connection. You will provide this in your config.exs file in this format
... config :my_app, TestListener, database: "postgres", username: "postgres", password: "postgres", hostname: "localhost" ...
The full list of options can be read in the documentation for Postgrex.
Copyright (c) 2014, Bitgamma OÜ michele@briksoftware.com
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