优雅地退出Laravel范围 [英] Gracefully exiting Laravel scopes

问题描述

我有一个作用域，它根据用户角色以限制方式起作用，您可以将一组规则转发到限制数据库最终输出的作用域.

I have a scope which is acting in a limiting fashion depending on a user role in a way that you can forward a set of rules to the scope limiting the final output from the DB.

一个真正简化的角色限制示例:

A really simplified role limit example:

{
    "first_name": "=foo%"
}

只会返回其 first_name 以 foo％开头的记录，这实际上意味着我已禁止具有该角色的用户查看任何以< foo％.

will only return records whose first_name begins with foo%, which effectively means that I have forbidden the user with that role to see any records which do not begin with foo%.

此方法的问题在于，如果某人没有施加任何限制，他将看到所有内容.我知道这是一个正确的假设，但是如果没有施加任何限制，我想禁止所有操作，因此，如果创建了新角色，则它没有任何权利.

The issue with this approach is that if someone has no limits imposed, he will see everything. I am aware that this is a valid assumption, but I would like to forbid everything if there are no limits imposed, so that if new role is created, it has no rights whatsoever.

当前，我在这种情况下抛出异常:

Currently I am throwing an exception for this case:

public function apply(Builder $builder, Model $model)
{
    $input = $this->getAuthValues(get_class($model));

    if (count($input) < 1) {
        throw new \Exception('No rights for you');
    }

    $jsonQuery = new JsonQuery($builder, $input); <-- class responsible for assembling the queries based on the input
    $jsonQuery->search();
}

但这当然也不例外.在这种情况下，我希望返回空数组.

But this of course is no exception. I would like empty array to be returned in that case.

我可以使用某种方法优雅地退出范围并返回空结果，而无需随后实际执行查询吗?

Can I use some method to gracefully exit the scope together with an empty result, without actually executing the query afterwards?

推荐答案

我来到一个解决方案，使一个不可能的查询返回0个结果.

I came to a solution to make an impossible query which would return 0 results.

public function apply(Builder $builder, Model $model)
{
    $input = $this->getAuthValues(get_class($model));

    if (count($input) < 1) {
        $builder->whereRaw('1 = 0');
        return;
    }

    $jsonQuery = new JsonQuery($builder, $input);
    $jsonQuery->search();
}

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