[英]Combining result of two different Queries from two different Model MongoDB
所以首先我有一个查询来查找用户借过的书,它将使用 Borrow 模型进行搜索
const bookqueryinitial = await Borrow.find({borrower_Id : String(_id), borrowStatus: req.query.status}).sort({"borrowDate": -1 }).skip(skip).limit(pageSize);
它会返回这样的结果
[
{
_id: new ObjectId("628ebcc10944a1223397b057"),
borrower_Id: '6278d1b6b4b7659470572e19',
borrowedbook_Id: '62710ac63ad1bfc6d1703162',
borrowStatus: 'pending',
borrowDate: 2022-05-25T23:33:21.849Z,
__v: 0
},
{
_id: new ObjectId("628d9c0b9a3dc72f4aa72f1a"),
borrower_Id: '6278d1b6b4b7659470572e19',
borrowedbook_Id: '62710ac63ad1bfc6d170314d',
borrowStatus: 'pending',
borrowDate: 2022-05-25T03:01:31.416Z,
__v: 0
}
]
接下来是我将映射结果的borrowedbook_Ids并将它们存储在一个数组中
const booksinsidequery = bookqueryinitial.map(bookids=>{
return bookids.borrowedbook_Id
})
然后我将搜索存储在数组中的 id 并在 Book 模型中搜索这些 id
const bookquery = await Book.find({ '_id': { $in: booksinsidequery } });
\\and the result is somethign like this
[
{
_id: new ObjectId("62710ac63ad1bfc6d170314d"),
title: "Girl who kicked the Hornet's Nest",
author: 'Larsson, Steig',
genre: [ 'fiction' ],
publisher: '',
dateOfPublication: 2017-10-25T00:00:00.000Z,
noOfCopies: 14,
type: 'Article',
form: 'Fiction',
isbn: '978-69793-4824559-56755-9',
dateAdded: 2003-04-23T00:00:00.000Z,
noOfBookmarks: [ [Object] ],
noOfLikes: [],
},
{
_id: new ObjectId("62710ac63ad1bfc6d1703162"),
title: 'We the Nation',
author: 'Palkhivala',
genre: [ 'philosophy' ],
publisher: '',
dateOfPublication: 2011-11-22T00:00:00.000Z,
noOfCopies: 94,
type: 'Book',
form: 'Non-fiction',
isbn: '978-65685-4156343-802140-8',
dateAdded: 2010-06-08T00:00:00.000Z,
noOfLikes: [],
noOfBookmarks: []
}
]
现在在将查询结果发送到客户端之前,我想将我的初始查询从 Borrow 模型绑定到我的 Book 模型,最终结果应该是这样的
[
{
_id: new ObjectId("62710ac63ad1bfc6d170314d"),
title: "Girl who kicked the Hornet's Nest",
author: 'Larsson, Steig',
genre: [ 'fiction' ],
publisher: '',
dateOfPublication: 2017-10-25T00:00:00.000Z,
noOfCopies: 14,
type: 'Article',
form: 'Fiction',
isbn: '978-69793-4824559-56755-9',
dateAdded: 2003-04-23T00:00:00.000Z,
noOfBookmarks: [ [Object] ],
noOfLikes: [],
//added properties based on matched condition (Borrow.borrowedbook_Id === Book._id)
borrowStatus: 'pending',
borrowDate: 2022-05-25T03:01:31.416Z,
},
{
_id: new ObjectId("62710ac63ad1bfc6d1703162"),
title: 'We the Nation',
author: 'Palkhivala',
genre: [ 'philosophy' ],
publisher: '',
dateOfPublication: 2011-11-22T00:00:00.000Z,
noOfCopies: 94,
type: 'Book',
form: 'Non-fiction',
isbn: '978-65685-4156343-802140-8',
dateAdded: 2010-06-08T00:00:00.000Z,
noOfLikes: [],
noOfBookmarks: [],
//added properties based on matched condition (Borrow.borrowedbook_Id === Book._id)
borrowStatus: 'pending',
borrowDate: 2022-05-25T23:33:21.849Z,
}
]
我怎样才能获得这些结果?
您可以使用 MongoDB 提供的聚合框架来实现这一点。
根据您的数据,这里是一个示例: https ://mongoplayground.net/p/DQJIbcqBDKM
Lookup :运算符帮助您连接不同集合之间的数据,匹配的数据将在一个数组中。 在这种情况下,称为借用
Unwind :将为指定数组上的每个项目创建一个文档
Addfields :允许您创建新属性,在这种情况下,您想要的两个属性“borrowStatus”和“borrowDate”
Project :此操作符允许您在下一阶段隐藏或显示数据。 在这种情况下,0 意味着我们将隐藏一个特定的属性
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