是否可以在Vapor中访问联接表中的字段? [英] Is it possible to access fields in a joined table in Vapor?

问题描述

我有一个通过Attends表关联的Persons表和一个Events表，这样当我希望记录某人将以特定角色参加特定事件的事实时，记录存在于Attends表中(例如组织者等):

I have a Persons table and an Events table that are related via an Attends table, such that a record exists the Attends table when I wish to record the fact that a person is due to attend a particular Event in a particular role (e.g. organiser, etc.):

Persons
+----+-------------+
| id | surname     |
+----+-------------+
|  1 | Robinson    |
|  2 | Savage      |
...

Events
+----+-----------------------+
| id | name                  |
+----+-----------------------+
|  1 | Half Term Competition |
|  2 | Christmas Competition |
...

attends
+---------+----------+--------+
| eventId | personId | roleId |
+---------+----------+--------+
|       1 |        1 |      1 |
|       1 |        2 |      6 |
...

我想产生一个事件中谁将去向以及他们在做什么的列表，但是我找不到在Vapor查询中使用.join()来做到这一点的方法.似乎可以对联接的表进行筛选，但不包括任何字段.我错过了什么吗?还是不可能?

I want to produce a list of who is going and what they are doing at an event, but I can't find a way of doing it using .join() in Vapor query. It seems that you can filter on the joined table, but not include any of the fields. Am I missing something or is this impossible?

我已经尝试过以下主题的多种变体:

I've tried many variations on the theme of:

Person.join(Attends.self).filter(Attends.self,Event.foreignIdKey == eventId)

我获得了正确的人"记录，但是无法从加入的Attends记录中访问他们的角色".

I get the correct Person records, but no way of accessing what their 'role' is from the joined Attends record.

如果我执行原始查询，则它将返回Node表示形式.我可以使用Leaf轻松地查看它，但是如何以我想生成带有图像等的PDF的方式来对其进行迭代并不是很明显.

If I do a raw query, then it returns a Node representation. I can easily view this using Leaf, but it is not at all obvious how to iterate over it in the way I would like to generate a PDF with images, etc.

推荐答案

流利的关系可能是您所需要的.

据我所知，您正在使用多对多"(同级)关系，因此此代码可能就是您想要的:

From what I can tell, you are using a Many to Many (sibling) relation, so this code might be what you want:

extension Persion {
    var roles: Siblings<Persion, Role, Pivot<Person, Role>> {
        return siblings()
    }
}

然后获得角色:

let roles = person.roles.all()

由于看不到您的代码，我可能会错了，但它应该为您提供一些指针.

I might have got this wrong as I can't see your code, but it should give you some pointers.

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