1 | <?php |
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2 | /* |
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3 | Plugin Name: Custom Metaboxes for Core |
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4 | */ |
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5 | |
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6 | class WP_Meta_Box { |
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7 | /** |
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8 | * The screen where the meta box will be shown. |
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9 | */ |
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10 | public $screen; |
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11 | |
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12 | /** |
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13 | * A unique slug to allow multiple meta boxes of the same class |
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14 | * to exist on the same screen. |
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15 | */ |
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16 | public $slug; |
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17 | |
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18 | /** |
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19 | * A unique identifier for the meta box. |
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20 | * |
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21 | * A string composed from the meta box class, screen, and slug. |
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22 | */ |
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23 | public $unique_id; |
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24 | |
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25 | /** |
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26 | * Arguments passed to the meta box constructor. |
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27 | */ |
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28 | public $args; |
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29 | |
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30 | /** |
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31 | * A registry that tracks each meta box instance. |
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32 | */ |
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33 | public static $registry; |
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34 | |
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35 | /** |
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36 | * A multi-dimensional array of registered meta fields, and their settings. |
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37 | */ |
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38 | public $meta_fields; |
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39 | |
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40 | |
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41 | /** |
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42 | * Constructor. |
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43 | * |
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44 | * Any subclasses MUST call parent::_construct( $screen, $args ). |
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45 | * |
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46 | * @param string $screen - The ID (string) for the screen where the meta box will be shown. |
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47 | * @param array $args - An array of supplied arguments. Optional. |
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48 | * |
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49 | * $args recognized by default: |
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50 | * title - The title of the meta box. |
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51 | * context - The context within the page where the box should show ('normal', 'advanced'). |
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52 | * priority - The priority within the context where the boxes should show ('high', 'low'). |
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53 | * slug - A unique string to identify the meta box. |
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54 | */ |
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55 | public function __construct( $screen, $args = array() ) { |
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56 | // Set variables |
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57 | $this->screen = $screen; |
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58 | $this->slug = empty( $args['slug'] ) ? '' : $args['slug']; |
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59 | |
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60 | // Remove slug from args |
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61 | unset( $args['slug'] ); |
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62 | |
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63 | // Set default args |
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64 | $defaults = array( |
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65 | 'title' => __( 'Untitled' , 'wordcampbase'), |
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66 | 'context' => 'side', |
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67 | 'priority' => 'default', |
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68 | ); |
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69 | $this->args = wp_parse_args( $args, $defaults ); |
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70 | |
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71 | |
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72 | add_action( 'save_post', array( $this, '_save' ), 10, 99 ); // Effectively infinite args. |
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73 | |
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74 | // Add the meta box to the registry. |
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75 | // Generates a slug if one doesn't already exist. |
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76 | WP_Meta_Box::registry()->add( $this ); |
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77 | |
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78 | // Construct the meta box's unique ID. |
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79 | $this->unique_id = get_class( $this ) . "_{$this->screen}_{$this->slug}"; |
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80 | |
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81 | // Bind hooks |
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82 | add_action( 'admin_init', array( $this, '_register_meta_box' ) ); |
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83 | add_action( 'admin_enqueue_scripts', array( $this, '_enqueue_scripts' ) ); |
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84 | } |
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85 | |
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86 | /** |
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87 | * Fetches the meta box registry. |
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88 | */ |
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89 | public static function registry() { |
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90 | if ( ! isset( WP_Meta_Box::$registry ) ) |
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91 | WP_Meta_Box::$registry = new WP_Meta_Box_Registry(); |
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92 | return WP_Meta_Box::$registry; |
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93 | } |
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94 | |
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95 | /** |
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96 | * Fires when the meta box is registered. Override in a subclass. |
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97 | */ |
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98 | protected function register() {} |
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99 | |
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100 | /** |
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101 | * Remove the meta box. |
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102 | */ |
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103 | public function remove() { |
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104 | // Make sure we've removed any data from the registry. |
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105 | WP_Meta_Box::registry()->remove( get_class( $this ), $this->screen, $this->slug ); |
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106 | |
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107 | // Unbind actions. |
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108 | remove_action( 'admin_init', array( $this, '_register_meta_box' ) ); |
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109 | remove_action( 'admin_enqueue_scripts', array( $this, '_enqueue_scripts' ) ); |
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110 | } |
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111 | |
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112 | /** |
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113 | * Register a post meta field. |
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114 | * |
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115 | * For use in a subclass. |
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116 | */ |
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117 | protected function register_meta_field( $meta_key, $args = array() ) { |
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118 | |
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119 | $defaults = array( |
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120 | 'type_class' => 'WP_Meta_Box_Field_Text', |
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121 | 'title_label' => $meta_key, |
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122 | 'data' => array(), // not yet implemented. Intended to preload form fields that require data (radios, selects, etc.) |
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123 | ); |
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124 | |
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125 | $args = wp_parse_args( $args, $defaults ); |
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126 | |
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127 | extract( $args ); |
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128 | |
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129 | // Store meta field details in an array for later. |
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130 | $this->meta_fields[] = $meta_field = array( |
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131 | 'class' => $meta_field_type_class = new $type_class(), |
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132 | 'meta_key' => $meta_key, |
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133 | 'sanitize_callback' => array( $meta_field_type_class, 'sanitize' ), |
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134 | 'auth_callback' => array( $meta_field_type_class, 'authorize' ), |
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135 | 'render_callback' => array( $meta_field_type_class, 'render_field' ), |
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136 | 'title_label' => $title_label, |
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137 | 'data' => array(), // not yet implemented. Intended to preload form fields that require data (radios, selects, etc.) |
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138 | ); |
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139 | add_action( 'admin_enqueue_scripts', array( $meta_field_type_class, 'enqueue_scripts' ) ); |
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140 | |
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141 | // Register meta with WordPress. Sets up sanitization and authorization callbacks. |
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142 | register_meta( 'post', $meta_key, $meta_field['sanitize_callback'], |
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143 | $meta_field['auth_callback'] ); |
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144 | } |
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145 | |
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146 | /** |
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147 | * Render the meta box. |
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148 | */ |
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149 | public function render_meta_box() { |
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150 | foreach ( $this->meta_fields as $meta_field ) { |
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151 | call_user_func( $meta_field['render_callback'], $meta_field ); |
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152 | } |
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153 | } |
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154 | |
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155 | /** |
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156 | * Enqueue meta box scripts. Override in a subclass. |
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157 | */ |
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158 | protected function enqueue_scripts() { |
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159 | foreach ( $this->meta_fields as $meta_field ) { |
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160 | call_user_func( array( $meta_field['class'], 'enqueue_scripts' ) ); |
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161 | } |
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162 | } |
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163 | |
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164 | /** |
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165 | * Save the meta fields' data. |
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166 | */ |
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167 | public function save() { |
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168 | global $post; |
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169 | foreach ( $this->meta_fields as $meta_field ) { |
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170 | // Capabilities check. |
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171 | if ( current_user_can( 'edit_post_meta', $post->ID, $meta_field['meta_key'] ) ) { |
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172 | // Check if the $_REQUEST key for the meta field is set. |
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173 | if ( isset( $_REQUEST['meta-field-' . $meta_field['meta_key']] ) ) { |
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174 | $meta_value = $_REQUEST['meta-field-' . $meta_field['meta_key']]; |
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175 | update_post_meta( $post->ID, $meta_field['meta_key'], $meta_value ); |
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176 | } |
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177 | } |
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178 | } |
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179 | } |
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180 | |
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181 | /** |
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182 | * Determine whether the meta box will be saved. Override in a subclass if necessary. |
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183 | * |
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184 | * Return true to save, false to cancel. |
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185 | * @param int The post ID. |
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186 | * @param $post The post object. |
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187 | */ |
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188 | protected function maybe_save( $post_id, $post ) { |
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189 | // Bail if we're autosaving |
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190 | if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) |
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191 | return; |
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192 | |
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193 | // @TODO Add revision check |
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194 | |
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195 | // Cap check |
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196 | if ( ! current_user_can( 'edit_post', $post_id ) ) |
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197 | die; |
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198 | |
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199 | return true; |
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200 | } |
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201 | |
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202 | /* ===================================================================== |
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203 | * INTERNAL FUNCTIONS |
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204 | * ===================================================================== */ |
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205 | |
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206 | /** |
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207 | * Internal function. Registers the meta box. |
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208 | */ |
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209 | public final function _register_meta_box() { |
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210 | $id = "{$this->unique_id}-meta-box"; |
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211 | |
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212 | add_meta_box( $id, $this->args['title'], array( $this, '_render' ), |
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213 | $this->screen, $this->args['context'], $this->args['priority'], |
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214 | $this->args ); |
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215 | |
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216 | $this->register(); |
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217 | } |
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218 | |
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219 | /** |
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220 | * Internal function. Ensures scripts are only loaded when necessary. |
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221 | */ |
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222 | public final function _enqueue_scripts() { |
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223 | $current_screen = get_current_screen(); |
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224 | |
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225 | if ( isset( $current_screen ) && $this->screen == $current_screen->id ) |
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226 | $this->enqueue_scripts(); |
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227 | } |
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228 | |
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229 | /** |
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230 | * Internal function, initiates the rendering process. |
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231 | */ |
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232 | public final function _render() { |
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233 | wp_nonce_field( "{$this->unique_id}_nonce", "_wpnonce_{$this->unique_id}", false ); |
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234 | |
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235 | $this->render_meta_box(); |
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236 | } |
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237 | |
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238 | /** |
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239 | * Internal function, initiates the saving process. |
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240 | */ |
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241 | public final function _save() { |
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242 | $current_screen = get_current_screen(); |
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243 | if ( ! isset( $current_screen ) || $this->screen != $current_screen->id |
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244 | || ! isset( $_REQUEST["_wpnonce_{$this->unique_id}"] ) ) |
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245 | return; |
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246 | // Nonce check (sorry, you don't have a choice about this one). |
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247 | check_admin_referer( "{$this->unique_id}_nonce", "_wpnonce_{$this->unique_id}" ); |
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248 | $args = func_get_args(); |
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249 | // Check if we're autosaving/capabilities check. |
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250 | if ( call_user_func_array( array( $this, 'maybe_save' ), $args ) ) { |
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251 | // Save the meta fields' data. |
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252 | call_user_func_array( array( $this, 'save' ), $args ); |
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253 | } |
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254 | } |
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255 | } |
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256 | |
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257 | |
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258 | |
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259 | /** |
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260 | * Meta Box Registry |
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261 | * |
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262 | * Implemented as singleton |
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263 | * |
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264 | */ |
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265 | class WP_Meta_Box_Registry { |
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266 | |
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267 | /** |
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268 | * WP_Meta_Box_Registry singleton implementation |
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269 | * |
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270 | * @var WP_Meta_Box_Registry |
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271 | */ |
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272 | private static $instance; |
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273 | |
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274 | private $instances = array(); |
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275 | |
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276 | /** |
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277 | * WP_Meta_Box_Registry singleton implementation |
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278 | * |
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279 | * @return WP_Meta_Box_Registry |
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280 | */ |
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281 | public static function instance() { |
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282 | if (null === self::$instance) |
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283 | self::$instance = new self(); |
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284 | return self::$instance; |
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285 | } |
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286 | |
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287 | /** |
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288 | * Search registry for meta box instances |
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289 | * |
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290 | * @return array result |
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291 | */ |
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292 | public function search($class_or_object, $screen = false, $slug = false) { |
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293 | $instances = array(); |
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294 | |
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295 | foreach($this->instances as $instance) { |
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296 | |
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297 | if ( ! $instance instanceof $class_or_object ) |
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298 | continue; |
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299 | |
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300 | if ( $screen !== false && $instance->screen !== $screen ) |
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301 | continue; |
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302 | |
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303 | if ( $slug !== false && $instance->slug !== $slug ) |
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304 | continue; |
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305 | |
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306 | $instances[] = $instance; |
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307 | } |
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308 | |
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309 | return $instances; |
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310 | } |
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311 | |
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312 | /** |
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313 | * Adds a meta box instance. |
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314 | * |
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315 | * If $instance->slug is defined, will use $slug. |
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316 | * If a meta box with the same slug exists, it will be overwritten. |
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317 | * |
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318 | * @param WP_Meta_Box $instance |
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319 | */ |
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320 | public function add( WP_Meta_Box $instance ) { |
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321 | static $counter = 0; |
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322 | |
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323 | $hash = spl_object_hash( $instance ); |
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324 | |
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325 | if ( !empty( $instance->slug ) ) { |
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326 | // If slug is specified, remove existing instance |
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327 | $instances = $this->find( $instance, $instance->screen, $instance->slug ); |
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328 | |
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329 | if ($instances) |
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330 | $this->remove($instances[0]); |
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331 | |
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332 | } else { |
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333 | // If no slug is specified, get the numerical index. |
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334 | // alternatively get the number of this instances' class by screen and count plus one. |
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335 | $instance->slug = ++$counter; |
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336 | } |
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337 | |
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338 | $this->instances[ $hash ] = $instance; |
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339 | } |
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340 | |
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341 | // in case this is still needed. |
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342 | public function get( WP_Meta_Box $instance ) { |
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343 | $hash = spl_object_hash( $instance ); |
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344 | |
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345 | if ( isset( $this->instances[ $hash ] ) ) |
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346 | return $instance; |
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347 | |
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348 | return false; |
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349 | } |
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350 | |
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351 | /** |
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352 | * Remove instance from registry |
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353 | * |
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354 | * @param WP_Meta_Box $instance |
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355 | */ |
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356 | public function remove( WP_Meta_Box $instance ) { |
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357 | $hash = spl_object_hash( $instance ); |
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358 | |
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359 | if ( isset( $this->instances[ $hash ] ) ) |
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360 | unset( $this->instances[ $hash ] ); |
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361 | } |
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362 | } |
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363 | |
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364 | /** |
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365 | * Base class for all other WP_Meta_Box_Fields to inherit from and override. |
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366 | * |
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367 | */ |
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368 | class WP_Meta_Box_Field { |
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369 | |
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370 | static function render_field( $meta_field ) { |
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371 | |
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372 | } |
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373 | |
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374 | /** |
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375 | * Sanitization callback for generic meta fields. |
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376 | * |
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377 | * Override in a subclass. |
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378 | */ |
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379 | public function sanitize( $meta_value, $meta_key ) { |
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380 | return $meta_value; |
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381 | } |
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382 | |
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383 | /** |
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384 | * Default authorization callback. |
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385 | * |
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386 | * Override in a subclass. |
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387 | */ |
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388 | public function authorize( $allowed, $meta_key, $post_ID, $user_id, $cap, $caps ) { |
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389 | return true; |
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390 | } |
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391 | |
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392 | /** |
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393 | * Enqueue scripts for particular field type. |
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394 | * |
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395 | * Override in a subclass. |
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396 | */ |
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397 | public function enqueue_scripts() {} |
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398 | } |
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399 | |
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400 | /** |
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401 | * Meta field class for the WordPress WYSIWYG Editor |
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402 | */ |
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403 | class WP_Meta_Box_Field_WP_Editor extends WP_Meta_Box_Field { |
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404 | |
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405 | /** |
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406 | * Render callback for generic meta fields. |
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407 | */ |
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408 | static function render_field( $meta_field ) { |
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409 | global $post; |
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410 | extract( $meta_field ); |
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411 | $meta_value = get_post_meta( $post->ID, $meta_key, true ); |
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412 | echo "<h4>$title_label</h4>"; |
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413 | wp_editor( $meta_value, 'meta-field-' . $meta_key ); |
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414 | } |
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415 | |
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416 | /** |
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417 | * Sanitization callback for text field. |
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418 | */ |
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419 | public function sanitize( $meta_value, $meta_key ) { |
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420 | |
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421 | $meta_value = wp_kses( $meta_value, wp_kses_allowed_html( 'post' ) ); |
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422 | return $meta_value; |
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423 | } |
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424 | } |
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425 | |
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426 | /** |
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427 | * Meta field class for a basic textbox |
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428 | */ |
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429 | class WP_Meta_Box_Field_Text extends WP_Meta_Box_Field { |
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430 | |
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431 | /** |
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432 | * Render callback for generic meta fields. |
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433 | */ |
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434 | static function render_field( $meta_field ) { |
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435 | global $post; |
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436 | extract( $meta_field ); |
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437 | $meta_value = get_post_meta( $post->ID, $meta_key, true ); |
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438 | echo "<h4>$title_label</h4>"; |
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439 | echo '<input type="text" id="' . $meta_key . '" name="meta-field-' . $meta_key . '" value="' . esc_attr( $meta_value ) .'">'; |
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440 | } |
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441 | |
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442 | /** |
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443 | * Sanitization callback for text field. |
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444 | */ |
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445 | public function sanitize( $meta_value, $meta_key ) { |
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446 | $meta_value = sanitize_text_field( $meta_value ); |
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447 | return $meta_value; |
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448 | } |
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449 | } |
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450 | |
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451 | |
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452 | |
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453 | |
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454 | |
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455 | |
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456 | |
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457 | /** |
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458 | * A usage example |
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459 | */ |
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460 | class WP_Basic_Meta_Box extends WP_Meta_Box { |
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461 | function __construct( $screen, $args = array() ) { |
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462 | // Call the WP_Meta_Box constructor. |
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463 | parent::__construct( $screen, $args ); |
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464 | |
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465 | $this->register_meta_field( |
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466 | '_basic_meta_box_test_field', |
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467 | array( |
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468 | 'type_class' => 'WP_Meta_box_Field_Text', |
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469 | 'title_label' => 'Some Title here' |
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470 | ) |
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471 | ); |
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472 | $this->register_meta_field( |
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473 | '_basic_meta_box_wp_editor_field', |
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474 | array( |
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475 | 'type_class' => 'WP_Meta_box_Field_WP_Editor', |
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476 | 'title_label' => 'WP Editor!' |
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477 | ) |
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478 | ); |
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479 | } |
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480 | } |
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481 | |
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482 | new WP_Basic_Meta_Box( 'post', array( 'title' => 'Basic Meta Box' ) ); |
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