VS Code中PHP代码报错Unexpected 'StringLiteral'. Expected ',' 求助排查

这个Unexpected 'StringLiteral'. Expected ','报错属于PHP字符串插值语法错误。你在双引号包裹的字符串中直接使用了$dbh->Record['po_number']这种带单引号的数组访问写法，PHP解析器无法正确识别复合结构的变量，会把数组键的单引号误判为字符串的结束标记，进而抛出语法错误。
同时原代码中a标签的href属性多嵌套了一层多余的单引号，就算语法修复后也会导致生成的链接地址异常。

方案1：用大括号包裹复合变量 #

用{}把字符串中所有复合结构的变量包裹起来，明确告诉PHP解析器这是一个完整的变量单元，修改后代码如下：

while ($dbh->next_record()) {
    $tracker_info = json_decode($dbh->Record['tracker_info'], TRUE);
    inform_sl_operations("PO{$dbh->Record['po_number']} needs Follow Up. Due: {$dbh->Record['alert']} \n" 
        . " Click to <a href=\"search_results.php?po_number={$dbh->Record['po_number']}\">view order</a>,"
        . " service@pmm.com", "PO {$dbh->Record['po_number']} needs Follow Up");
}

方案2：提前提取变量（可读性更高） #

先把需要用到的字段值提取为独立变量，再拼接到字符串中，避免在字符串里写复杂的数组访问结构：

while ($dbh->next_record()) {
    $tracker_info = json_decode($dbh->Record['tracker_info'], TRUE);
    $po_number = $dbh->Record['po_number'];
    $alert = $dbh->Record['alert'];
    inform_sl_operations("PO$po_number needs Follow Up. Due: $alert \n" 
        . " Click to <a href=\"search_results.php?po_number=$po_number\">view order</a>,"
        . " service@pmm.com", "PO $po_number needs Follow Up");
}

两种方案都可以解决语法报错问题，同时也修复了原代码中href属性多余单引号的问题。

内容的提问来源于stack exchange，提问作者CodeForGood