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up.protocol X-Up-Validate
HTTP header

This request header contains the [name] of a form field being validated.

When seeing this header, the server is expected to validate (but not save) the form submission and render a new copy of the form with validation errors. See the documentation for input[up-validate] for more information on how server-side validation works in Unpoly.

The server is free to respond with any HTTP status code, regardless of the validation result. Unpoly will always consider a validation request to be successful, even if the server responds with a non-200 status code. This is in contrast to regular form submissions, where a non-200 status code will often update a different element.


Assume we have an auto-validating form field:

  <input name="email" up-validate>

When the input is changed, Unpoly will submit the form with an additional header:

X-Up-Validate: email
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