如何在查询中使用数组字段匹配 mongoid 文档？
我正在尝试将文档与 Mongoid/Mongodb 相匹配，其中查询中使用数组字段。我一直在努力解决 $elemMatch 但似乎无法得到它。
上下文
项目可以有admin、member、reader用户- 这些用户由
项目<引用/code> (HABTM) - 我希望能够找到以下项目：
- 用户 A 是
管理员 - 用户 B 是
管理员或成员 - ..等等..
- 用户 A 是
示例
给定一个 Project来自Rails控制台的文档：
[#<Project _id: 4f44355a9f5b7f385a000003,
_type: nil, name: "Project ABC",
desc: "some description",
admin_ids:
[BSON::ObjectId('123')],
member_ids:
[BSON::ObjectId('456'),
BSON::ObjectId('789')],
reader_ids: []
>]
我有以下代码：
@projects = Project.any_of({:admin_ids => [current_user.id]},
{:member_ids => [current_user.id]}).entries
只要admin_ids和member_ids匹配current_user.id /em> 两个数组中都只有一个值。根据上面的代码：
- 尝试匹配用户
'123'给出正确的结果 - 尝试匹配用户
'456'没有给出结果（不正确）
$elemMatch
基于研究中，我认为我应该使用 $elemMatch 但缺少一些东西。
根据上面的 Project 文档代码：
// test case: this works with array of one
Project.all(conditions: {:admin_ids => "123"}).entries
// failure case: empty result
Project.all(conditions: {:member_ids => {'$elemMatch' => {:id => '456' } }}).entries
// failure case: empty result
Project.all(conditions: {:member_ids => {'$elemMatch' => {:id => BSON::ObjectId('4f44a4019f5b7f3d5200000d') } }}).entries
I am trying to match documents with Mongoid/Mongodb where array fields are used in the query. I've been struggling with $elemMatch but can't seem to get it.
Context
- A
Projectcan haveadmin,member,readerusers - These users are referenced by a
Project(HABTM) - I want to be able to find projects where:
- User A is
admin - User B is
adminormember - .. etc ..
- User A is
Example
Given a Project document from Rails console:
[#<Project _id: 4f44355a9f5b7f385a000003,
_type: nil, name: "Project ABC",
desc: "some description",
admin_ids:
[BSON::ObjectId('123')],
member_ids:
[BSON::ObjectId('456'),
BSON::ObjectId('789')],
reader_ids: []
>]
I had the following code:
@projects = Project.any_of({:admin_ids => [current_user.id]},
{:member_ids => [current_user.id]}).entries
Which matches current_user.id across either admin_ids and member_ids as long as there was only a single value in either of the arrays. As per the code above:
- Trying to match user
'123'gives correct result - Trying to match user
'456'gives no result (incorrect)
$elemMatch
Based on researching, I think I should be using $elemMatch but am missing something.
As per the Project document code above:
// test case: this works with array of one
Project.all(conditions: {:admin_ids => "123"}).entries
// failure case: empty result
Project.all(conditions: {:member_ids => {'$elemMatch' => {:id => '456' } }}).entries
// failure case: empty result
Project.all(conditions: {:member_ids => {'$elemMatch' => {:id => BSON::ObjectId('4f44a4019f5b7f3d5200000d') } }}).entries
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评论（2）
您需要在查询时删除数组。
那应该有效。
You need to get rid of the array while querying.
That should work.
我认为你应该能够使用
$in而不是 $elemMatch - 作为 mongodocs 说：您是否尝试过类似以下的操作？
I think you should just be able to use
$inrather than $elemMatch - as the mongodocs say:Have you tried something like the following?