FilterFormatter

This is a mix format plugin which filters user-configurable sigils and files by piping their contents to a given command line program.

The program is expected to read input via stdin and produce formatter output on stdout. An exit code of 0 is considered success, any other exit code is considered failure.

This makes it easy to hook any command line tool into mix format.

Installation

First, add filter_formatter to your list of dependencies in mix.exs:

def deps do
  [
    {:filter_formatter, "~> 0.1.0"}
  ]
end

Next, fetch dependencies. This will also pull in Rambo since that's what this plugin uses for running external programs. To make sure that Rambo works, run mix compile.rambo once to build any required intermediate binaries.

mix deps.get && mix compile.rambo

Rambo depends on a helper binary written in Rust. In case the mix compile.rambo step prints a message like

** (RuntimeError) Rambo does not ship with binaries for your environment.

Make sure to have Rust available before running mix compile.rambo. Using Homebrew, this is a matter of running

brew install rust

Finally, add FilterFormatter to your .formatter.exs file and configure the filter_formatter option such that it associates sigils and/or file extensions with commands to execute:

[
  inputs: ["*.{ex,exs,heex}", "priv/*/seeds.exs", ...],
  plugins: [FilterFormatter],
  filter_formatter: [
      ...
  ]
]

Example: formatting SQL via pg_format

This configuration makes mix format pass the contents This specification which makes mix format pass the contents of the SQL sigil as well as the code in any .sql files through pg_format.

[
  plugins: [FilterFormatter],
  filter_formatter: [
    [
      extensions: [".sql"],
      sigils: [:SQL],
      executable: "pg_format",
      args: ["-L"]
    ]
  }
]

Example: formatting SQL via SQLFluff

Here's another example of formatting SQL, this time using SQLFluff:

[
  plugins: [FilterFormatter],
  filter_formatter: [
    [
      extensions: [".sql"],
      sigils: [:SQL],
      executable: "sqlformat",
      args: ["format", "-", "--dialect", "postgres", "--nocolor", "--disable-progress-bar"]
    ]
  ]
]

Please see the API documentation for more information.