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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

PHP
// General errors (all fields)
$errors = $this->validation->display_errors();
// Returns: <ul class="validation-errors">...</ul> or null

// Inline errors for specific field
$email_errors = $this->validation->display_errors(['first_arg' => 'email']);
// Returns: <ul class="validation-errors validation-errors--inline">...</ul> or empty string

// JSON API response (terminates script)
$this->validation->display_errors(['first_arg' => 422]);
// Sends HTTP 422 with JSON error array, then exits

// Custom HTML wrapper
$errors = $this->validation->display_errors([
    'first_arg' => '<div class="alert alert-danger">',
    'closing_html' => '</div>'
]);

// Typical form controller pattern
public function submit() {
    $this->validation->set_rules('email', 'Email', 'required|valid_email');
    if (!$this->validation->run()) {
        $data['errors'] = $this->validation->display_errors();
        $this->view('form', $data);
        return;
    }
    // Process valid data...
}

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.