display_errors()

public function display_errors(array $data = []): ?string

Description

Displays validation errors in one of three formats: general HTML list, inline field‑specific errors, or JSON API response. This method is the object‑oriented counterpart to the validation_errors() helper function.

The format is determined by the first_arg value in the $data array:

null or omitted – General errors for all fields (wrapped in <ul class="validation-errors">)
string (field name) – Inline errors for a specific field
integer (400‑499) – JSON response with HTTP error code

Parameters

Parameter	Type	Description
$data	array	Associative array with optional keys: `first_arg` – string\|int\|null (field name, HTTP code, or null) `closing_html` – ?string (closing HTML tag for general errors)

Return Value

Type	Description
string\|null	HTML string – For general or inline errors null – If no errors exist (general mode) JSON response – Script terminates with `exit` (API mode)

Example Usage

Notes

Errors are retrieved from $_SESSION['form_submission_errors'].
In JSON mode (HTTP code), the script terminates after output – no return value.
For inline errors, an empty string is returned if the field has no errors.
After errors are displayed, they are cleared from session (to prevent duplicate display).
Use the helper validation_errors() for simpler, function‑based access.