# `Soundcheck.Check.Design.UnreadAssign`
[🔗](https://github.com/leonqadirie/soundcheck/blob/v0.1.0/lib/soundcheck/check/design/unread_assign.ex#L1)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

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

## Explanation

Flags assign keys a LiveView or LiveComponent sets but never reads:
not in its templates, not in any layout, and not through
`socket.assigns` in its code. Every assign lives in the process and
goes through change tracking for nothing.

Before:

    def mount(_params, _session, socket) do
      {:ok, assign(socket, posts: list_posts(), page_size: 20)}
    end

    # no template or callback reads @page_size

After:

    def mount(_params, _session, socket) do
      {:ok, assign(socket, posts: list_posts())}
    end

Only literal keys count. When code passes the assigns map along whole
(`helper(socket.assigns)`, `<.panel {assigns} />`), any key could be
read there, and the check skips the module. Keys read only by an
`on_mount` hook or a parent are reported; list them in
`ignore_assigns`.

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`.

### `:ignore_assigns`

  Keys never reported (atoms).

*This parameter defaults to* `[:page_title]`.

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

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*Consult [api-reference.md](api-reference.md) for complete listing*