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php - Compare meta_value in WP_Query that is stored in the form of serialized array

问题描述

I have a meta box associated with a custom post type. The meta box allows the user to select multiple options from a dropdown and then saves it in the form of the serialized array into the database. If the user selects only one option the meta_value is stored as an integer but if a user selects multiple options then it is saved in the form of a serialized array.

Below are the functions that display and save my meta box

function av_add_meta_box() {

  $post_types = array( 'advertisements' );

  foreach ( $post_types as $post_type ) {

    add_meta_box(
      'avd_screen_meta_box',         // Unique ID of meta box
      'Set Screen',     // Title of meta box
      'av_display_meta_box', // Callback function
      $post_type                   // Post type
    );

  }

}
add_action( 'add_meta_boxes', 'av_add_meta_box' );

// display meta box
function av_display_meta_box( $post ) {

  $value = get_post_meta( $post->ID, '_av_meta_key', true );

  if ( isset( $values['av-meta-box'] ) ) {
        $value = esc_attr( $values['ued-av-box'][0] );
    }

  wp_nonce_field( basename( __FILE__ ), 'av_meta_box_nonce' );

  //echo "<pre>"; print_r($value) ; echo "</pre>";
  ?>
  <select id="av-meta-box" type="text" name="av-meta-box[]" multiple="multiple">
    <option value="">Select Screen</option>
    <?php $screens =  json_decode(apply_filters("av_load_screens", "all")); 
     foreach ($screens as $screen) { 
        $location_name = json_decode(apply_filters("av_load_locations", $screen->location));
        $selected = "";
        if(gettype($value) == "array"){
          $selected = (in_array($screen->id, $value))?"selected":"";
        } else{
          $selected = ($screen->id == $value)?"selected":"";
        }  ?>
        <option <?php echo $selected; ?> value="<?php echo $screen->id; ?>"><?php echo $screen->screen_name." - ".$location_name[0]->location_name." (".$location_name[0]->pin.") "; ?></option><?php
      } ?>
  </select>

<?php

}

// save meta box
function av_save_meta_box( $post_id ) {

  $is_autosave = wp_is_post_autosave( $post_id );
  $is_revision = wp_is_post_revision( $post_id );

  $is_valid_nonce = false;

  if ( isset( $_POST[ 'av_meta_box_nonce' ] ) ) {

    if ( wp_verify_nonce( $_POST[ 'av_meta_box_nonce' ], basename( __FILE__ ) ) ) {

      $is_valid_nonce = true;

    }

  }

  if ( $is_autosave || $is_revision || !$is_valid_nonce ) return;

  if ( array_key_exists( 'av-meta-box', $_POST ) ) {

    update_post_meta(
      $post_id,                                            // Post ID
      '_av_meta_key',                                // Meta key
      array_map( 'strip_tags', $_POST[ 'av-meta-box' ])// Meta value
    );

  }

}
add_action( 'save_post', 'av_save_meta_box' );

And Below are the arguments what I'm passing to my WP_Query

$args = array(
                'post_type' => 'advertisements',
                'meta_query' => array (
                                    'key' => '_av_meta_key',
                                    'value' => 6,
                                    'compare' => 'IN'
                                )
            );

The above WP_Query returns all post with having meta value 6(integer). But what if the meta_value is stored in a serialized array like a:3:{i:0;s:1:"6";i:1;s:1:"7";i:2;s:1:"8";}

In my case, the post_id:20, meta_key:_av_meta_key and meta_value:a:3:{i:0;s:1:"6";i:1;s:1:"7";i:2;s:1:"8";}

I want my WP_Query to return the post with id 20 either the meta_value is 6 or 7 or 8.

标签： phpwordpresswordpress-theming

解决方案

我建议将（多个）值保存到数据库中的多行中，以避免从一开始就出现问题。WordPress 支持使用相同的键为自定义字段保存多个值。

您可以将保存价值的代码重写为：

if ( array_key_exists( 'av-meta-box', $_POST ) ) {
    delete_post_meta( $post_id, '_av_meta_key' );

    $values = array_map( 'absint', $_POST[ 'av-meta-box' ] );

    foreach ( $values as $value ) {
          add_post_meta( $post_id, '_av_meta_key', $value, false );
    }
}

这样，您可以编写查询而不必担心序列化数据。从数据库中获取值很简单：

$values = get_post_meta( $post_id, '_av_meta_key', false );

PS：我建议使用自定义字段插件以避免编写重复代码。正如我在上面快速建议的那样，它还可以帮助您解决这个问题。

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