Yii2的save()方法容易出错的地方

如果save()返回true, 但是数据没有保存成功，则应该是开启了事务且已经回滚

如果save()返回false, 则使用$model->errors查看错误原因

可以设置$model的场景，对具体的场景进行验证; 没有指定场景的验证规则会在所有的场景通用

save()方法有两个参数，第一个参数为是否开启验证，第二个字段为验证的字段，但是会调用beforeBValidate()

源码如下所示：

public function save($runValidation = true, $attributeNames = null)
    {
        if ($this->getIsNewRecord()) {
            return $this->insert($runValidation, $attributeNames);
        } else {
            return $this->update($runValidation, $attributeNames) !== false;
        }
    }

public function update($runValidation = true, $attributeNames = null)
    {
        if ($runValidation && !$this->validate($attributeNames)) {
            return false;
        }
        return $this->updateInternal($attributeNames);
    }

public function validate($attributeNames = null, $clearErrors = true)
    {
        if ($clearErrors) {
            $this->clearErrors();
        }

        if (!$this->beforeValidate()) {
            return false;
        }

        $scenarios = $this->scenarios();
        $scenario = $this->getScenario();
        if (!isset($scenarios[$scenario])) {
            throw new InvalidParamException("Unknown scenario: $scenario");
        }

        if ($attributeNames === null) {
            $attributeNames = $this->activeAttributes();
        }

        foreach ($this->getActiveValidators() as $validator) {
            $validator->validateAttributes($this, $attributeNames);
        }
        $this->afterValidate();

        return !$this->hasErrors();
    }

protected function updateInternal($attributes = null)
    {
        if (!$this->beforeSave(false)) {
            return false;
        }
        $values = $this->getDirtyAttributes($attributes);
        if (empty($values)) {
            $this->afterSave(false, $values);
            return 0;
        }
        $condition = $this->getOldPrimaryKey(true);
        $lock = $this->optimisticLock();
        if ($lock !== null) {
            $values[$lock] = $this->$lock + 1;
            $condition[$lock] = $this->$lock;
        }
        // We do not check the return value of updateAll() because it's possible
        // that the UPDATE statement doesn't change anything and thus returns 0.
        $rows = static::updateAll($values, $condition);

        if ($lock !== null && !$rows) {
            throw new StaleObjectException('The object being updated is outdated.');
        }

        if (isset($values[$lock])) {
            $this->$lock = $values[$lock];
        }

        $changedAttributes = [];
        foreach ($values as $name => $value) {
            $changedAttributes[$name] = isset($this->_oldAttributes[$name]) ? $this->_oldAttributes[$name] : null;
            $this->_oldAttributes[$name] = $value;
        }
        $this->afterSave(false, $changedAttributes);

        return $rows;
    }