Question

我在MongoDB中有一个收集testcol的文档，如下所示：

{
_id:111,
"xxx":"aaa",
"yyy":"bbb"
}

我想更新文档中的yyy字段，如果找到该字段然后更新它，如果找不到该字段，则不要做任何事情。

当我运行我的mongo db update命令时，如db.testcol.update({_id:0},{$set:{"zzz":"ccc"}},{upsert: false})。我故意把这个领域作为＆＃34; zzz＆＃34;在更新命令中，它不应该做任何事情。但是当我运行上面的更新命令时，它插入了新字段＆＃34; zzz＆＃34;在上面的文件中虽然upsert是假的。我知道upsert将不会/将插入文档而不是字段，但由于我是MongoDB的新手，我只是试一试。有谁能告诉我如何处理这个问题？

Answer 1

如果var pdfbooks = UIWebView() var nIndex:NSInteger! var post: Post! var db : DBHelperA3lam = DBHelperA3lam() var book : a3lamDa3waModel? @IBAction func backbtn(_ sender: Any) { if let navController = self.navigationController { navController.popViewController(animated: true) } } override func viewDidLoad() { super.viewDidLoad() var config : SwiftLoader.Config = SwiftLoader.Config() config.size = 150 config.spinnerColor = .brown config.foregroundColor = .black config.foregroundAlpha = 0.5 config.titleTextColor = .brown SwiftLoader.setConfig(config) if "" != book?.bookPath { // self.activityIND.isHidden = true // self.activityIND.stopAnimating() SwiftLoader.hide() UIApplication.shared.isNetworkActivityIndicatorVisible = false loadReader(filePaht: (book?.bookPath)!) } else { let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] let strName = book?.id let filePath = "\(documentsPath)/"+strName!+".pdf" let fileManager = FileManager.default // self.activityIND.startAnimating() SwiftLoader.show(title: "Loading...", animated: true) UIApplication.shared.isNetworkActivityIndicatorVisible = true if fileManager.fileExists(atPath: filePath) { // self.loadFromUrl(path: filePath) loadReader(filePaht: (book?.bookPath)!) return; } let reference = FIRStorage.storage().reference(forURL: (self.book?.bookURL)!) reference.data(withMaxSize: 50 * 1024 * 1024) { (data, error) -> Void in if (error != nil) { print ("unable to download pdf file from Firebase Storage") // self.activityIND.isHidden = false // self.activityIND.startAnimating() SwiftLoader.show(title: "Loading...", animated: true) UIApplication.shared.isNetworkActivityIndicatorVisible = true } else { if ((try! data?.write(to: URL.init(fileURLWithPath: filePath, isDirectory: false))) != nil) { // self.loadFromUrl(path: filePath) print ("pdf file is downloaded from Firebase Storage") self.db.upDate(id: (self.book?.id)!, bookPath: filePath) // self.activityIND.isHidden = true SwiftLoader.hide() self.loadReader(filePaht: filePath) UIApplication.shared.isNetworkActivityIndicatorVisible = false } } } } } func loadReader(filePaht : String) { let document = ReaderDocument(filePath: filePaht, password: nil) if document != nil { let readerVC = ReaderViewController(readerDocument: document) readerVC?.delegate = self readerVC?.modalTransitionStyle = UIModalTransitionStyle.crossDissolve readerVC?.modalPresentationStyle = UIModalPresentationStyle.fullScreen self.navigationController?.pushViewController(readerVC!, animated: true) } } func dismiss(_ viewController: ReaderViewController!) { // _ = self.navigationController?.popToRootViewController(animated: true) if let a3lamDa3waVC = self.navigationController?.viewControllers[1] { _ = navigationController?.popToViewController(a3lamDa3waVC, animated: true) } } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() }字段存在，您可以在查询中使用$exists运算符仅匹配文档：

@IBOutlet weak var collectionView: UICollectionView!


var posts = [Post]()
let db : DBHelperA3lam = DBHelperA3lam()
var arrayBooks = [a3lamDa3waModel]()
var selectedIndexPath : IndexPath = IndexPath()
var post: Post!

override func viewDidLoad() {

    var config : SwiftLoader.Config = SwiftLoader.Config()
    config.size = 150
    config.spinnerColor = .brown
    config.foregroundColor = .black
    config.foregroundAlpha = 0.5
    config.titleTextColor = .brown


    SwiftLoader.setConfig(config)


    super.viewDidLoad()
 //   activityIndicator.isHidden = false

    SwiftLoader.show(title: "Loading...", animated: true)


    self.arrayBooks.removeAll()
    self.arrayBooks.append(contentsOf: self.db.fetchAll())
    self.collectionView.reloadData()
    DataService.ds.REF_POSTS.observe(.value, with: { (snapshot) in


        if let snapshot = snapshot.children.allObjects as? [FIRDataSnapshot] {

            for snap in snapshot {
                print ("SNAP: \(snap)")

                if let postDict = snap.value as? Dictionary<String, AnyObject>{
                    let key = snap.key
                    let post = Post(postKey: key , postData: postDict)
                    self.posts.append(post)
                    self.db.insertBook(id: postDict["id"] as! String, imgName: postDict["id"] as! String, imgPath: "", bookName: postDict["book_name"] as! String, bookPath: "", imageURL: postDict["image_path"] as! String, bookURL: postDict["book_path"] as! String, caption: "")




                }
            }
        } else {

        }
        self.arrayBooks.removeAll()
        self.arrayBooks.append(contentsOf: self.db.fetchAll())
        self.collectionView.reloadData()

    })


    collectionView.delegate = self
    collectionView.dataSource = self

}
func getFilePath(name : String) -> String {

    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
    let filePath = documentsPath+"/"+name
    return filePath
}


@IBAction func backbtn(_ sender: Any) {
    if let navController = self.navigationController {
        navController.popViewController(animated: true)
    }
}



func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {


    return arrayBooks.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    let book = arrayBooks[indexPath.item]
     SwiftLoader.hide()

    if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)as? CollectionViewCellA3lamDa3wa {

        cell.initWithBook(book: book)

        return cell

    }else {
        return CollectionViewCellA3lamDa3wa()
    }


}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
    self.selectedIndexPath = indexPath
    self.performSegue(withIdentifier: "showImage", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?)
{

    if segue.identifier == "showImage"
    {
        let vc = segue.destination as! showA3lamDa3waVC
        vc.book = self.arrayBooks[self.selectedIndexPath.row]

    }
}

Answer 2

你正在使用upsert错误。请参阅mongo的文档here

如果upsert为true且没有文档符合查询条件，则update（）插入单个文档。更新将创建新文档。如果 upsert为true，并且有符合查询条件的文档， update（）执行更新。

仅在MongoDB中存在时才更新字段

2 个答案: