我发现其他几个帖子也在问同样的问题，但出于某种原因，我似乎无法找到适合我的解决方案。为了澄清，我希望有一个应用于帖子但不包含任何值的自定义字段，以便我可以设置一个模板帖子（在本例中为公文包项目），并简单地复制它，但在字段不适用的地方省略值，当然，如果没有值，我不希望显示相关的html。所以，我得到的是：

<?php $fbb_CurrentMetaSet = get_post_meta($post->ID, \'fbb_ProjectData_Process\', false);
            if (!empty($fbb_CurrentMetaSet)){?>
            <div id="fbb_ProjectData_Process" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title"><h5>Process:</h5></div>
                <div>
                        <?php foreach($fbb_CurrentMetaSet as $fbb_MetaDataSingle){
                            echo \'<div>\'.$fbb_MetaDataSingle.\'</div>\'; 
                        }?> 
                </div>
            </div>
            <?php } ?>

如果我只检查自定义字段是否存在（if（$fbb\\u CurrentMetaSet）），则此代码可以工作，但由于某些原因！empty（）方法无效。有人能解释为什么吗？仅供参考，我正在使用最新的wordpress和x主题。

可能是更大的上下文产生了一个解释，所以下面我粘贴了整个相关代码集。我的测试代码可以在最后一节中找到。一旦我让它工作起来，我打算将其复制到上面的类似部分：

<div id="fbb_ProjectDataWrap">
            <div id="fbb_ProjectData_Client" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title"><h5>Client:</h5></div>
                <ul>
                <?php $fbb_CurrentMetaSet = get_post_meta($post->ID, \'fbb_ProjectData_Client\', false);?>
                    <?phpforeach($fbb_CurrentMetaSet as $fbb_MetaDataSingle){
                        echo \'<li>\'.$fbb_MetaDataSingle.\'</li>\'; 
                    }
                }?>
                </ul>
            </div>
            <div id="fbb_ProjectData_Tools" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title"><h5>Tools:</h5></div>
                <ul>
                <?php $fbb_CurrentMetaSet = get_post_meta($post->ID, \'fbb_ProjectData_Tools\', false); ?>                    
                    <?php foreach($fbb_CurrentMetaSet as $fbb_MetaDataSingle){
                        echo \'<li>\'.$fbb_MetaDataSingle.\'</li>\';
                    } ?>
                </ul>
            </div>
            <div id="fbb_ProjectData_About" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title"><h5>About:</h5></div>
                <div>
                <?php $fbb_CurrentMetaSet = get_post_meta($post->ID, \'fbb_ProjectData_AboutTheProject\', false); ?>                  
                    <?php foreach($fbb_CurrentMetaSet as $fbb_MetaDataSingle){
                        echo \'<div>\'.$fbb_MetaDataSingle.\'</div>\';
                    } ?>
                </div>
            </div>
            <?php $fbb_CurrentMetaSet = get_post_meta($post->ID, \'fbb_ProjectData_Process\', false);
            if (!empty($fbb_CurrentMetaSet)){?>
            <div id="fbb_ProjectData_Process" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title"><h5>Process:</h5></div>
                <div>
                        <?php foreach($fbb_CurrentMetaSet as $fbb_MetaDataSingle){
                            echo \'<div>\'.$fbb_MetaDataSingle.\'</div>\'; 
                        }?> 
                </div>
            </div>
            <?php } ?>
        </div>

$meta   = get_post_meta( get_the_ID() );

// First make sure we have data before continuing
if ( $meta ) :
    // Get your field values and set defaults
    $fields            = [];
    $field_names       = [\'Client\', \'Tools\', \'About\', \'Process\'];
    foreach ( $field_names as $field_name ) {
        if ( \'About\' === $field_name ) {
            $name = \'AboutTheProject\';
        } else {
            $name = $field_name;
        }
        $fields[$field_name] = ( isset( $meta[\'fbb_ProjectData_\' . $name] ) )
            ? filter_var( $meta[\'fbb_ProjectData_\' . $name][0], FILTER_SANITIZE_STRING ) 
            : \'\';
    }

    // Lets make sure we have at least one key/value pair with avalue
    if ( array_filter( $fields ) ) : ?>
        <div id="fbb_ProjectDataWrap">
        <?php // Lets loop through $fields and display them
        foreach ( $fields as $key=>$field ) : 
            // Make sure $field is not empty, if so, continue
            if ( !$field )
                continue;

            // We have values, lets display them
            ?>

            <div id="fbb_ProjectData_<?php echo $key; ?>" class="fbb_ProjectDataSetSection">
                <div class="fbb_Title">
                    <h5><?php echo $key; ?>:</h5>
                </div>
                <ul>
                    <li>
                        <div>
                            <?php echo $field; ?>
                        </div>
                    </li>
                </ul>
            </div>
        <?php endforeach; ?> 
        </div>
    <?php
    endi