[英]MongoDB get documents from a collection not in other collection
I'm trying to get the documents from a collection where aren't in other collection (the common NOT IN clause in SQL).我正在尝试从不在其他集合中的集合中获取文档(SQL 中常见的 NOT IN 子句)。
If I run the next query:如果我运行下一个查询:
db.Companies_Movies.aggregate([
{
$project:
{
"CompanyList.Movies.Code" : 1
}
},
{
$match:
{
"CompanyList.CodeCompany": "23"
}
},
{
$lookup:
{
from: "Movies",
localField: "CompanyList.Movies.Code",
foreignField: "Movie.Code",
as: "matched_docs"
}
}
]);
This query shows the movies includes in CompanyList.Movies.Code and in Movie.Code.此查询显示 CompanyList.Movies.Code 和 Movie.Code 中包含的电影。 Good.好的。 But I just have the rest of movies includes in CompanyList.Movies whose codes aren't included in Movie.Code.但我只有 rest 的电影包含在 CompanyList.Movies 中,其代码未包含在 Movie.Code 中。
As Nikos Tsagkas said in Get "data from collection b not in collection a" in a MongoDB shell query it should be sufficient to include the following sentence:正如 Nikos Tsagkas 在Get "data from collection b not in collection a" in a MongoDB shell 查询中所说,包含以下句子就足够了:
{
$match: { "matched_docs": { $eq: [] } }
}
But when I run my final code, it doesn't returns anything:但是当我运行我的最终代码时,它不会返回任何内容:
db.Companies_Movies.aggregate([
{
$project:
{
"CompanyList.Movies.Code" : 1
}
},
{
$match:
{
"CompanyList.CodeCompany": "23"
}
},
{
$lookup:
{
from: "Movies",
localField: "CompanyList.Movies.Code",
foreignField: "Movie.Code",
as: "matched_docs"
}
},
{
$match: { "matched_docs": { $eq: [] } }
}
]);
There are 59 documents that are not returned by this code.此代码未返回 59 个文档。
This is my pipeline I've created in MongoDB Compass after Tom's changes and it still doesn't work:这是我在 Tom 更改后在 MongoDB Compass 中创建的管道,但它仍然无法正常工作:
[{
$match:
{
'CompanyList.CodeCompany': '23'
}
},
{
$lookup:
{
from: 'Movies',
localField: 'CompanyList.Movies.Code',
foreignField: 'Movie.Code',
as: 'docs'
}
},
{
$project:
{
'CompanyList.Movies.Code': 1,
'CompanyList.CodeCompany': 1
}
},
{
$match:
{
docs:{ $eq: [] }
}
}]
If I delete the $project, it not works either.如果我删除 $project,它也不起作用。
Sample Data (reduced)样本数据(减少)
Companies_Movies collection:公司_电影合集:
{
_id:ObjectId("61bf47b974641866e1244e65"),
"CompanyList": {
"CodeCompany": "23",
"NameCompany": "Company Name Entertainment",
"Movies": [{
"Code": "123",
"Name": "Title 1",
"Order": 1,
"UserDescription": null
}, {
"Code": "124",
"Name": "Title 2",
"Order": 2,
"UserDescription": null
}, {
"Code": "125",
"Name": "Title 3",
"Order": 3,
"UserDescription": null
}],
"DateInserted": {
"$date": "2021-12-13T17:30:06.824Z"
}
}
}
Movies collection:电影合集:
[{
_id:ObjectId("61bf57bc9d1f93b7ae5fa785"),
"Movie": {
"Code": "123",
"OriginalTitle": "Title 1",
"Year": 2021
},
_id:ObjectId("61bf57bc9d1f93b7ae5fa786"),
"Movie": {
"Code": "124",
"OriginalTitle": "Title 2",
"Year": 2021
},
_id:ObjectId("61bf57bc9d1f93b7ae5fa787"),
"Movie": {
"Code": "125",
"OriginalTitle": "Title 3",
"Year": 2021
},
_id:ObjectId("61bf57bc9d1f93b7ae5fa788"),
"Movie": {
"Code": "126",
"OriginalTitle": "Title 4",
"Year": 2021
}
}]
Anyone know what might be happening?有谁知道可能会发生什么?
Thanks to everyone.谢谢大家。
This is simply caused by your $project
stage, after you run:这只是由您的$project
阶段引起的,在您运行后:
{
$project: {
"CompanyList.Movies.Code" : 1
}
},
You're data will look like this:您的数据将如下所示:
{
CompanyList: [
{
Movies: { code: "123", ... other fields }
}
]
}
Now you're trying to match "CompanyList.CodeCompany": "23"
, but the field CodeCompany
simply does not exist anymore as you did not provide it in the project stage.现在您正在尝试匹配"CompanyList.CodeCompany": "23"
,但CodeCompany
字段根本不存在,因为您没有在项目阶段提供它。
So just change you're projection stage to include fields you will use in later stages:因此,只需更改您的投影阶段以包含您将在稍后阶段使用的字段:
{
$project: {
"CompanyList.Movies.Code" : 1,
"CompanyList.CodeCompany": 1
}
},
Tom.汤姆。 Thanks for your help.谢谢你的帮助。
Your solution not works.您的解决方案不起作用。
This is my pipeline created in MongoDB Compass after your changes:这是我在更改后在 MongoDB Compass 中创建的管道:
[{
$match:
{
'CompanyList.CodeCompany': '23'
}
},
{
$lookup:
{
from: 'Movies',
localField: 'CompanyList.Movies.Code',
foreignField: 'Movie.Code',
as: 'docs'
}
},
{
$project:
{
'CompanyList.Movies.Code': 1,
'CompanyList.CodeCompany': 1
}
},
{
$match:
{
docs:{ $eq: [] }
}
}]
If I delete the $project, it not works either.如果我删除 $project,它也不起作用。
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