Ecto.DevLogger

An alternative logger for Ecto queries.

It inlines bindings into the query, so it is easy to copy-paste logged SQL and run it in any IDE for debugging without manual transformation of common elixir terms to string representation (binary UUID, DateTime, Decimal, json, etc). Also, it highlights db time to make slow queries noticeable. Source table and inlined bindings are highlighted as well.

Installation

The package can be installed by adding ecto_dev_logger to your list of dependencies in mix.exs:

def deps do
  [
    {:ecto_dev_logger, "~> 0.14"}
  ]
end

Then disable default logger for your repo in config file for dev mode:

if config_env() == :dev do
  config :my_app, MyApp.Repo, log: false
end

And install telemetry handler in MyApp.Application:

Ecto.DevLogger.install(MyApp.Repo)

Telemetry handler will be installed only if log configuration value is set to false.

That's it.

The docs can be found at https://hexdocs.pm/ecto_dev_logger.

Development Only Installation

If you turn off repo logging for any reason in production, you can configure ecto_dev_logger to only be available in development. In your mix.exs, restrict the installation to :dev:

def deps do
  [
    {:ecto_dev_logger, "~> 0.10", only: :dev}
  ]
end

In MyApp.Application, an additional function is required:

defmodule MyApp.Application do
  @moduledoc "..."

  def start(_type, _args) do
    maybe_install_ecto_dev_logger()

    # ...
  end

  if Code.ensure_loaded?(Ecto.DevLogger) do
    defp maybe_install_ecto_dev_logger, do: Ecto.DevLogger.install(MyApp.Repo)
  else
    defp maybe_install_ecto_dev_logger, do: :ok
  end

  # ...
end

Format queries

It is possible to format queries using a :before_inline_callback option. Here is an example of setup using pgFormatter as an external utility:

defmodule MyApp.Application do
  def start(_type, _args) do
    Ecto.DevLogger.install(MyApp.Repo, before_inline_callback: &__MODULE__.format_sql_query/1)
  end

  def format_sql_query(query) do
    case System.shell("echo $SQL_QUERY | pg_format -", env: [{"SQL_QUERY", query}], stderr_to_stdout: true) do
      {formatted_query, 0} -> String.trim_trailing(formatted_query)
      _ -> query
    end
  end
end

Running tests

You need to run a local postgres server for the tests to interact with. This is one way to do it:

~$ docker run -p5432:5432 --rm --name ecto_dev_logger_postgres -e POSTGRES_PASSWORD=postgres -d postgres