javascript - 如果 mongodb 中不存在如何更新值

Question

db.books.find({ "status": "readED", $and: [ { "listingStatus": { $not: { $exists: true } } } ] }).forEach(function(book){

     db.getSiblingDB('reading').bookListing.find({"sellerSku": book.sellerSku, "sellerId":book.seller},{"sellerId": 1, "sellerSku": 1}).forEach(function(bookListing){

     printjson(bookListing);


});

});

当我运行这个时，它给出了

 {
    "_id" : ObjectId("582cb4ad5a5a380sadas038dd2f72"),
    "sellerId" : "e0a82c3d-079asdas0-49asda97-aasdascdf-0c320e3d7022",
    "sellerSku" : "te227"
}
{
    "_id" : ObjectId("582cb4ae5a5a380038dd2f73"),
    "sellerId" : "e0a82casdsa3d-07asdas90-4997-acdf-0c320e3d7022",
    "sellerSku" : "TE231"
}

所以这意味着

有书已读，但listingstatus不存在(通常listingstatus必须存在)

在阅读数据库中，有图书列表收藏。通常我需要做的是:

• 如果某本书已读且listingstatus不存在，并且该图书sellersku存在于书单集合中，则需要更新listingstatus。

而不是

  printjson(bookListing);

我需要更新

book.update(listingstatu) 在每个中，但这在 javascript 中可能吗？

这个怎么样

db.getSiblingDB('book').books.update({ "seller": bookListing.sellerId, "sellerSku": bookListing.sellerSku },{ $set: {"listingStatus" : "LISTING_CREATED"}})

而不是

printjson(bookListing)

它将再次调用图书数据库。

但是为了测试我做了这个而不是

打印json

  db.getSiblingDB('book').books.find({ "seller": bookListing.sellerId, "sellerSku": bookListing.sellerSku },{ $set: {"listingStatus" : "LISTING_CREATED"}})

但它没有显示任何内容

Answer 1

将 printjson(bookListing) 替换为:

        // set listingStatus 
        bookListing.listingStatus = "someRandomValue"; 
        // save the document. As a document already exist in the collection 
        // with this _id, it will update it. 
        db.books.save(listingStatus);

所以你的代码变成:

    db.books.find({ "status": "readED", $and: [ { "listingStatus": { $not: { $exists: true } } } ] }).forEach(function(book){

         db.getSiblingDB('reading').bookListing.find({"sellerSku": book.sellerSku, "sellerId":book.seller},{"sellerId": 1, "sellerSku": 1}).forEach(function(bookListing){

        // set listingStatus 
        bookListing.listingStatus = "someRandomValue"; 
        // save the document. As a document already exist in the collection 
        // with this _id, it will update it. 
        db.books.save(listingStatus);

    });
  });

这将仅更新匹配的文档