Basics
This check is disabled by default.
Learn how to enable it via .credo.exs.
This check has a base priority of normal and works with any version of Elixir.
Explanation
Flags @key reads of an optional attr that declares no default.
Phoenix puts only declared defaults into a component's assigns, so
when a caller omits the attr, @key raises KeyError, even inside
:if={@key}.
Before:
attr :icon, :string
def badge(assigns), do: ~H"<span :if={@icon}>{@icon}</span>"After:
attr :icon, :string, default: nil
def badge(assigns), do: ~H"<span :if={@icon}>{@icon}</span>"Reading the attr as assigns[:icon] never raises and is not
reported. Attrs marked required: true, :global attrs, keys the
component body assigns before rendering (assign_new/3 included),
components whose body rebinds assigns through another function, and
LiveView or LiveComponent render/1 functions are skipped.
Confidence: medium. Tier: syntactic (works without compiling).
Check-Specific Parameters
Use the following parameters to configure this check:
:excluded_paths
Paths to skip (atoms, binaries as path segments, or regexes).
This parameter defaults to [~r/\/test\//, "test"].
:strict
Unused.
This parameter defaults to false.
General Parameters
Like with all checks, general params can be applied.
Parameters can be configured via the .credo.exs config file.