結合來自兩個不同模型MongoDB的兩個不同查詢的結果

所以首先我有一個查詢來查找用戶借過的書，它將使用 Borrow 模型進行搜索

const bookqueryinitial = await Borrow.find({borrower_Id : String(_id), borrowStatus: req.query.status}).sort({"borrowDate": -1 }).skip(skip).limit(pageSize);

它會回傳這樣的結果

[
   {
     _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
    }
 ]

接下來是我將映射結果的borrowedbook_Ids并將它們存盤在一個陣列中

const booksinsidequery = bookqueryinitial.map(bookids=>{
      return bookids.borrowedbook_Id
    })

然后我將搜索存盤在陣列中的 id 并在 Book 模型中搜索這些 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: []
   }
 ]

現在在將查詢結果發送到客戶端之前，我想將我的初始查詢從 Borrow 模型系結到我的 Book 模型，最終結果應該是這樣的

 [
   {
    _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,
   }
 ]

我怎樣才能獲得這些結果？

uj5u.com熱心網友回復：

您可以使用 MongoDB 提供的聚合框架來實作這一點。

根據您的資料，這里是一個示例：https ://mongoplayground.net/p/DQJIbcqBDKM

• Lookup：運算子幫助您連接不同集合之間的資料，匹配的資料將在一個陣列中。在這種情況下，稱為借用

• Unwind：將為指定陣列上的每個專案創建一個檔案

• Addfields：允許您創建新屬性，在這種情況下，您想要的兩個屬性“borrowStatus”和“borrowDate”

• Project：此運算子允許您在下一階段隱藏或顯示資料。在這種情況下，0 意味著我們將隱藏一個特定的屬性

標籤：javascript mongodb 猫鼬

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