Bylaw.Credo.Check.Ecto.PreferRepoAggregateCount (bylaw_credo v0.1.0-alpha.1)

Basics

This check has a base priority of high and works with any version of Elixir.

Explanation

Prefer Repo.aggregate(queryable, :count) over loading rows with Repo.all and counting them in memory.

Examples

Avoid:

  Repo.all(query) |> Enum.count()
  Enum.count(Repo.all(query))
  query |> Repo.all() |> length()

Prefer:

  Repo.aggregate(query, :count)

Prefer Repo.exists?/1 or not Repo.exists?/1 over comparing Repo.aggregate(query, :count) to 0 or 1 for existence checks. Avoid:

  Repo.aggregate(query, :count) > 0
  Repo.aggregate(query, :count) == 0

Prefer:

  Repo.exists?(query)
  not Repo.exists?(query)

Notes

This check uses static AST analysis, so it favors clear source-level patterns over runtime behavior.

Options

This check has no check-specific options. Configure it with an empty option list.

Usage

Add this check to Credo's checks: list in .credo.exs:

%{
  configs: [
    %{
      name: "default",
      checks: [
        {Bylaw.Credo.Check.Ecto.PreferRepoAggregateCount, []}
      ]
    }
  ]
}

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.