Question

当我运行Doctrine Migration时，出现以下错误：

迁移20141217162533在执行期间失败。错误运行时   注意：只应通过引用传递变量

[Symfony \ Component \ Debug \ Exception \ ContextErrorException]运行时   注意：只应通过引用传递变量

在$this->validateUsername行上

。当我发表评论时，它运作正常。

这似乎是一个非常奇怪的运行时错误，我无法理解为什么我会得到这个。

public function up(Schema $schema)
{
    foreach ($this->old_users as $old_user) {
        if ($this->validateUsername($old_user['email']) === false or $this->checkDNSRecord($old_user['email']) === false) {
            $this->addSql("INSERT INTO User (email, joined_on, unsubscribed) VALUES ('" . $old_user['email'] . "', '" . $old_user['joined_on'] . "', 0)");
        }
    }
}

/**
 * Validate the username/email address based on the structure (e.g. username@domain.com)
 *
 * @param $email
 *
 * @return bool
 */
public function validateUsername($email)
{
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        // email is NOT valid
        return false;
    } else {
        // email is valid
        return true;
    }
}

/**
 * Validate the MX line of the DNS record for the host of the email address (e.g. @aol.co.uk)
 *
 * @param $email
 *
 * @return bool
 */
public function checkDNSRecord($email)
{
    if (checkdnsrr(array_pop(explode('@', $email)), 'MX')) {
        return true;
    } else {
        return false;
    }
}

Answer 1

问题是像array_pop这样的函数通过引用获取数组，因为它改变了它的内容（从数组中删除了最后一个元素）。现在，您将explode的结果直接传递给array_pop array_pop(explode('@', $email))因此，php无法通过引用传递该结果，因为它不是变量。解决方案非常简单，只需将explode结果保存在临时变量中：

<?php
/* ... */
$mailParts = explode('@', $email);
checkdnsrr(array_pop($mailParts), 'MX');
/* ... */

Answer 2

这会更好吗？

public function up(Schema $schema)
{
    foreach ($this->old_users as $old_user) {
        $old_email = $old_user['email'];
        if ($this->validateUsername($old_email) === false or $this->checkDNSRecord($old_user['email']) === false) {
            $this->addSql("INSERT INTO User (email, joined_on, unsubscribed) VALUES ('" . $old_user['email'] . "', '" . $old_user['joined_on'] . "', 0)");
        }
    }
}

Symfony 2 ContextErrorException运行Doctrine迁移时，只应通过引用传递变量

2 个答案: