Issue #2846909 by mikeker, Gravypower: Placeholder support

config/schema/better_exposed_filters.exposed_form.schema.yml

@@ -61,6 +61,9 @@ better_exposed_filters.*:
       label: 'More options'
       type: mapping
       mapping:
+        placeholder_text:
+          type: text
+          label: 'Placeholder text for text fields'
         bef_select_all_none:
           type: boolean
           label: 'Add select all/none links'

src/Plugin/views/exposed_form/BetterExposedFilters.php

@@ -509,6 +509,16 @@ Title Desc|Z -> A</pre> Leave the replacement text blank to remove an option alt
         '#description' => $this->t('Places this element in the secondary options portion of the exposed form.'),
       );
 
+      if ($filter instanceof StringFilter) {
+        // Allow users to specify placeholder text.
+        $bef_options[$label]['more_options']['placeholder_text'] = [
+          '#type' => 'textfield',
+          '#title' => $this->t('Placeholder text'),
+          '#description' => $this->t('Text to be shown in the text field until it is edited. Leave blank for no placeholder to be set.'),
+          '#default_value' => $existing[$label]['more_options']['placeholder_text'],
+        ];
+      }
+
       // Allow rewriting of filter options for any filter. String and numeric
       // filters allow unlimited filter options via textfields, so we can't
       // offer rewriting for those.
@@ -855,6 +865,12 @@ Title Desc|Z -> A</pre> Leave the replacement text blank to remove an option alt
       // configurable.
       $field_id = $filters[$label]->options['expose']['identifier'];
 
+      // Check for placeholder text.
+      if (!empty($settings[$label]['more_options']['placeholder_text'])) {
+        // @todo: Add token replacement for placeholder text.
+        $form[$label]['#placeholder'] = $settings[$label]['more_options']['placeholder_text'];
+      }
+
       // Handle filter value rewrites.
       if (!empty($options['more_options']['rewrite']['filter_rewrite_values'])) {
         $form[$field_id]['#options'] = $this->rewriteOptions($form[$field_id]['#options'] , $options['more_options']['rewrite']['filter_rewrite_values']);
@@ -1490,6 +1506,7 @@ Title Desc|Z -> A</pre> Leave the replacement text blank to remove an option alt
     $filter_defaults = array(
       'bef_format' => 'default',
       'more_options' => array(
+        'placeholder_text' => '',
         'bef_select_all_none' => FALSE,
         'bef_select_all_none_nested' => FALSE,
         'bef_collapsible' => FALSE,
@@ -1524,4 +1541,5 @@ Title Desc|Z -> A</pre> Leave the replacement text blank to remove an option alt
     }
     return $settings;
   }
+
 }