Validate required field

Author: pontikis

class-cliowp-settings-page.php

@@ -224,7 +224,7 @@ public function add_settings() {
 $this->option_group,
 'cliowp_sp_input1',
 array(
-'sanitize_callback' => 'sanitize_text_field',
+'sanitize_callback' => array( $this, 'sanitize_input1' ),
 'default' => 'input1 test',
 )
 );
@@ -293,6 +293,24 @@ public function input1_html() {
 <?php
 }
 
+/**
+ * Undocumented function
+ *
+ * @param string $input The input value.
+ */
+public function sanitize_input1( $input ) {
+if ( true === empty( $input ) ) {
+add_settings_error(
+'cliowp_sp_input1',
+'cliowp_sp_input1_error',
+__( 'Input1 cannot be empty', 'cliowp-settings-page' ),
+);
+return get_option( 'cliowp_sp_input1' );
+}
+
+return sanitize_text_field( $input );
+}
+
 /**
  * Undocumented function
  */