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form_open_upload()

function form_open_upload(string $location, array $attributes = []): string

Description

Generates the opening tag for an HTML form configured for file uploads. This function is identical to form_open() but automatically adds the enctype="multipart/form-data" attribute required for file submissions.

Important: Forms that accept file uploads must use form_open_upload() instead of form_open(). Without the proper encoding type, file data won't be transmitted to the server.

Parameters 

Parameter Type Description
$location string The URL or path where the form will be submitted.
$attributes array (optional) HTML attributes for the form element. Defaults to an empty array ([]).

Return Value

Type Description
string The HTML opening tag for the form with enctype="multipart/form-data".

Example #1: Basic File Upload Form

Example #2: File Upload with Custom Attributes

Example #3: Multiple File Uploads

Example #4: Form with File Upload in a View

  • Always use form_open_upload() for forms containing form_file_select() inputs.
  • The enctype="multipart/form-data" attribute is automatically added and cannot be overridden.
  • File upload forms must use POST method (default).
  • For security, always validate file types, sizes, and names server-side.
  • Use $_FILES superglobal to access uploaded file data in your controller.
  • Large file uploads may require adjusting PHP configuration (upload_max_filesize, post_max_size).
  • For multiple file uploads, add multiple="multiple" attribute to the file input and use array notation in the name (e.g., name="files[]").
  • Remember that form_close() includes CSRF protection, which also applies to file upload forms.

Common Issues

If your $_FILES array is empty after form submission, check the following:

  • You're using form_open_upload() instead of form_open()
  • The form method is POST (default)
  • File size doesn't exceed upload_max_filesize in php.ini
  • The total form data (including files) doesn't exceed post_max_size in php.ini
  • You're accessing the correct field name in $_FILES (matches the name attribute of your file input)