# `Soundcheck.Check.Warning.EventPayloadMismatch`
[🔗](https://github.com/leonqadirie/soundcheck/blob/v0.1.0/lib/soundcheck/check/warning/event_payload_mismatch.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 `normal` and works with any version of Elixir.

## Explanation

Flags `phx-click` and `phx-click-away` events whose payload lacks a
key that every matching `handle_event/3` clause requires. No clause
matches the params, so the click raises `FunctionClauseError`.

Before:

    <button phx-click="delete">Delete</button>

    def handle_event("delete", %{"id" => id}, socket)

After:

    <button phx-click="delete" phx-value-id={post.id}>Delete</button>

A click sends the element's `phx-value-*` attributes, its `value`
when the element has one, and the `value:` map of a `JS.push`.
Browsers lowercase attribute names, so `phx-value-postId` arrives as
`"postid"`. The check reads the receivers' compiled clauses, so it
routes events as `UnhandledEvent` (SC101) does and skips events no
clause names. It stays silent when an element spreads attributes
(`{@rest}`), when a `JS.push` value is not a literal map, and for
receivers whose handlers `attach_hook/4` can intercept. Function
component calls count as sending `value`, since the rendered element
may carry one. List keys that a `LiveSocket` `metadata` callback adds
to click events in `metadata_keys`.

Confidence: medium. Tier: semantic (run `mix compile` before `mix credo`).

## 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`.

### `:metadata_keys`

  Keys that `LiveSocket` `metadata` callbacks add to every click.

*This parameter defaults to* `[]`.

## 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*