Question

Wordpress附带了处理CRUD操作的wpdb类。我感兴趣的这个类的两个方法是insert()（CRUD中的C）和update()（CRUD中的U）。

当我想在mysql数据库列中插入NULL时出现问题 - wpdb类将PHP空变量转义为空字符串。如何告诉Wordpress使用实际的MySQL NULL而不是MySQL字符串？

Answer 1

如果您希望它兼容，则必须SHOW COLUMN并确定是否允许NULL。如果允许，那么如果值为空（$ v），则在查询中使用val = NULL。

$foo = null;
$metakey = "Harriet's Adages";
$metavalue = "WordPress' database interface is like Sunday Morning: Easy.";

if ($foo == null) {
$wpdb->query( $wpdb->prepare( "
    INSERT INTO $wpdb->postmeta
    ( post_id, meta_key, meta_value, field_with_null )
    VALUES ( %d, %s, %s, NULL )", 
        10, $metakey, $metavalue ) );
} else {
$wpdb->query( $wpdb->prepare( "
    INSERT INTO $wpdb->postmeta
    ( post_id, meta_key, meta_value, field_with_null )
    VALUES ( %d, %s, %s, %s)", 
        10, $metakey, $metavalue, $foo ) );
}

Answer 2

这是您问题的解决方案。在“ wp-content ”文件夹中，创建一个名为“ db.php ”的文件并将此代码放入其中：

<?php

// setup a dummy wpdb to prevent the default one from being instanciated
$wpdb = new stdclass();

// include the base wpdb class to inherit from
//include ABSPATH . WPINC . "/wp-db.php";


class wpdbfixed extends wpdb
{
    function insert($table, $data, $format = null) {
        $formats = $format = (array) $format;
        $fields = array_keys($data);
        $formatted_fields = array();
        $real_data = array();
        foreach ( $fields as $field ) {
            if ($data[$field]===null)
            {
                $formatted_fields[] = 'NULL';
                continue;
            }
            if ( !empty($format) )
                $form = ( $form = array_shift($formats) ) ? $form : $format[0];
            elseif ( isset($this->field_types[$field]) )
                $form = $this->field_types[$field];
            else
                $form = '%s';
            $formatted_fields[] = "'".$form."'";
            $real_data[] = $data[$field];
        }
        //$sql = "INSERT INTO <code>$table</code> (<code>&quot; . implode( '</code>,<code>', $fields ) . &quot;</code>) VALUES (" . implode( ",", $formatted_fields ) . ")";
        $sql = "INSERT INTO $table (" . implode( ',', $fields ) . ") VALUES (" . implode( ",", $formatted_fields ) . ")";
        return $this->query( $this->prepare( $sql, $real_data) );
    }

    function update($table, $data, $where, $format = null, $where_format = null)
    {
        if ( !is_array( $where ) )
            return false;

        $formats = $format = (array) $format;
        $bits = $wheres = array();
        $fields = (array) array_keys($data);
        $real_data = array();
        foreach ( $fields as $field ) {
            if ($data[$field]===null)
            {
                $bits[] = "$field = NULL";
                continue;
            }
            if ( !empty($format) )
                $form = ( $form = array_shift($formats) ) ? $form : $format[0];
            elseif ( isset($this->field_types[$field]) )
                $form = $this->field_types[$field];
            else
                $form = '%s';
            $bits[] = "$field = {$form}";

            $real_data[] = $data[$field];
        }

        $where_formats = $where_format = (array) $where_format;
        $fields = (array) array_keys($where);
        foreach ( $fields as $field ) {
            if ( !empty($where_format) )
                $form = ( $form = array_shift($where_formats) ) ? $form : $where_format[0];
            elseif ( isset($this->field_types[$field]) )
                $form = $this->field_types[$field];
            else
                $form = '%s';
            $wheres[] = "$field = {$form}";
        }

        $sql = "UPDATE $table SET " . implode( ', ', $bits ) . ' WHERE ' . implode( ' AND ', $wheres );

        return $this->query( $this->prepare( $sql, array_merge($real_data, array_values($where))) );
    }

}

$wpdb = new wpdbfixed(DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);
?>

通过这种方式，您可以将空值与wpdb！

一起使用

Answer 3

我在Wordpress StackExchange论坛上找到了这个，对我来说效果很好。

// Add a filter to replace the 'NULL' string with NULL
add_filter( 'query', 'wp_db_null_value' );

global $wpdb;
$wpdb->update(
    'table',
    array( 
        'status' => 'NULL',
    ), 
    array( 'id' => 1 ) 
);

// Remove the filter again:
remove_filter( 'query', 'wp_db_null_value' );

并且函数wp_db_null_value是：

/**
* Replace the 'NULL' string with NULL
* 
* @param  string $query
* @return string $query
*/

function wp_db_null_value( $query )
{
  return str_ireplace( "'NULL'", "NULL", $query ); 
}

因为在我的情况下我不能使用$ db-＆gt; prepare（）函数...

Answer 4

wpdb insert()和update()使用NULL值，它是在多年前修补的，但在法典中从未提及。

您的情况：

$wpdb->update(
    'table',
    array( 
        'status' => null,
    ), 
    array( 'id' => 1 ), 
    null, 
    '%d'
);

参考：https://core.trac.wordpress.org/ticket/15158#no0

Answer 5

我尝试编辑此处列出的其他解决方案之一，因为它导致格式数组与数据数组错位，但失败了。

这是一个从最新版本的wordpress修改wpdb的解决方案，以便允许使用insert（）和update（）将空值插入和更新到SQL表中：

/*
 * Fix wpdb to allow inserting/updating of null values into tables
 */
class wpdbfixed extends wpdb
{
    function insert($table, $data, $format = null) {
        $type = 'INSERT';
        if ( ! in_array( strtoupper( $type ), array( 'REPLACE', 'INSERT' ) ) )
            return false;
        $this->insert_id = 0;
        $formats = $format = (array) $format;
        $fields = array_keys( $data );
        $formatted_fields = array();
        foreach ( $fields as $field ) {
            if ( !empty( $format ) )
                $form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
            elseif ( isset( $this->field_types[$field] ) )
                $form = $this->field_types[$field];
            else
                $form = '%s';

            //***Steve Lee edit begin here***
            if ($data[$field]===null) {
                unset($data[$field]); //Remove this element from array, so we don't try to insert its value into the %s/%d/%f parts during prepare().  Without this, array would become shifted.
                $formatted_fields[] = 'NULL';
            } else {
                $formatted_fields[] = $form; //Original line of code
            }
            //***Steve Lee edit ends here***
        }
        $sql = "{$type} INTO `$table` (`" . implode( '`,`', $fields ) . "`) VALUES (" . implode( ",", $formatted_fields ) . ")";
        return $this->query( $this->prepare( $sql, $data ) );
    }

    function update($table, $data, $where, $format = null, $where_format = null)
    {
        if ( ! is_array( $data ) || ! is_array( $where ) )
            return false;

        $formats = $format = (array) $format;
        $bits = $wheres = array();
        foreach ( (array) array_keys( $data ) as $field ) {
            if ( !empty( $format ) )
                $form = ( $form = array_shift( $formats ) ) ? $form : $format[0];
            elseif ( isset($this->field_types[$field]) )
                $form = $this->field_types[$field];
            else
                $form = '%s';

            //***Steve Lee edit begin here***
            if ($data[$field]===null)
            {
                unset($data[$field]); //Remove this element from array, so we don't try to insert its value into the %s/%d/%f parts during prepare().  Without this, array would become shifted.
                $bits[] = "`$field` = NULL";
            } else {
                $bits[] = "`$field` = {$form}"; //Original line of code
            }
            //***Steve Lee edit ends here***
        }

        $where_formats = $where_format = (array) $where_format;
        foreach ( (array) array_keys( $where ) as $field ) {
            if ( !empty( $where_format ) )
                $form = ( $form = array_shift( $where_formats ) ) ? $form : $where_format[0];
            elseif ( isset( $this->field_types[$field] ) )
                $form = $this->field_types[$field];
            else
                $form = '%s';
            $wheres[] = "`$field` = {$form}";
        }

        $sql = "UPDATE `$table` SET " . implode( ', ', $bits ) . ' WHERE ' . implode( ' AND ', $wheres );
        return $this->query( $this->prepare( $sql, array_merge( array_values( $data ), array_values( $where ) ) ) );
    }

}
global $wpdb_allow_null;
$wpdb_allow_null = new wpdbfixed(DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);

将此代码插入总是运行的地方，例如您的functions.php，然后正常使用新的全局$ wpdb_allowed_null-＆gt; insert（）和 - ＆gt; update（）。

我更喜欢这种方法而不是覆盖默认的$ wpdb，以保留其他Wordpress和其他插件所期望的数据库行为。

Wordpress数据库insert（）和update（） - 使用NULL值

5 个答案: