form-action-whitespace¶

Added in NEXT_DJANGOFMT_VERSION · Related issues · View source

Fix is always available.

What it does¶

Checks for leading or trailing whitespace in the action attribute of <form> elements.

Why is this bad?¶

The URL parser strips leading and trailing ASCII whitespace when resolving an HTML URL attribute, so the spaces are inert at runtime and only add noise to the source. They are commonly an accidental artefact of inserting a template tag inside the quotes.

Values containing template interpolation are skipped: the surrounding whitespace is usually intentional padding around a {% url %} tag and cannot be safely trimmed without knowing the rendered output. Only the action attribute is checked; sibling attributes such as data-action may legitimately span multiple lines.

Example¶

<form action=" /submit/ "></form>

Use instead:

<form action="/submit/"></form>

Fix safety¶

This rule's fix is marked as safe: the URL parser strips leading and trailing ASCII whitespace from URL attribute values, so trimming the literal source preserves runtime semantics. Author code reading the raw attribute (e.g. form.getAttribute("action"), strict-equality dispatch, HTMX or web-component integrations that observe the literal string) would see the trimmed value, but relying on the surrounding whitespace is vanishingly rare.

References¶

• URL Standard: basic URL parser
• HTML spec: the form element