用node.js，mongoose，gridfs-stream讀取文件

我正在使用mongoose和gridfs-stream來存儲和讀取mongodb中的文件。我在這裏的例子如下：https://github.com/aheckmann/gridfs-stream 用node.js，mongoose，gridfs-stream讀取文件

寫入文件到數據庫工作正常，但我面臨讀取文件的問題。

什麼MongoDB的外觀（顯示集合）

fs.chunks 
fs.files

什麼文件索引外觀（db.fs.files.find（））

{ "_id" : ObjectId("5140392659851df70b000001"), 
"filename" : "cover", 
"contentType" : "binary/octet-stream", 
"length" : 85734, 
"chunkSize" : 262144, 
"uploadDate" : ISODate("2013-03-13T08:30:30.299Z"), 
"aliases" : null, 
"metadata" : null, 
"md5" : "4476b26067daa0677978ba501308a35d" }

然後我用這個代碼來獲取文件命名爲「蓋」

... 
var gfs = Grid(mongoose.connection.db, mongoose.mongo) 
var readstream = gfs.createReadStream('cover')

時出現錯誤：

Error: cover does not exist 
at self.collection.self.fileId (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/gridfs/gridstore.js:198:26) 
at Cursor.nextObject (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:654:35) 
at Cursor.close (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:960:5) 
at Cursor.nextObject (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:654:17) 
at Cursor.nextObject.commandHandler (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/cursor.js:631:14) 
at Db._executeQueryCommand (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:1702:5) 
at g (events.js:185:14) 
at EventEmitter.emit (events.js:115:20) 
at Server.Base._callHandler (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/base.js:130:25) 
at Server.connect.connectionPool.on.server._serverState (/mypath/node_modules/mongoose/node_modules/mongodb/lib/mongodb/connection/server.js:517:20)

我用Google搜索了一下，發現了一些可能的相關鏈接：

https://github.com/mongodb/node-mongodb-native/issues/621

Why gridfs get isn't working on file id (ObjectId) only by filename

來源

2013-03-13 LKS

，如果我取代「文件名」與「5140392659851df70b000001」，它的工作原理：'VAR readstream = gfs.createReadStream（ '5140392659851df70b000001'）'。我猜這個原因與設置密鑰有關？ – LKS 2013-03-13 09:57:46

你也可以看看驅動程序流的實現http://mongodb.github.com/node-mongodb-native/api-generated/gridstore.html#stream – christkv 2013-03-15 07:57:24

只是好奇，你是否存儲對文件的引用一個貓鼬創建的文件？我正在研究使用GridFS，並想知道人們如何實現它。 – Leonidas 2013-03-20 03:36:59

在GitHub上的示例代碼是一個有點誤導;我最初收到了你所做的同樣的錯誤信息。就我而言，這是由於我在寫入流完成之前試圖讀取文件。我解決了這個做事件處理程序內讀取"close"：

var fs = require("fs"), 
    mongo = require("mongodb"), 
    Grid = require("gridfs-stream"), 
    gridfs, 
    writeStream, 
    readStream, 
    buffer = ""; 

mongo.MongoClient.connect("mongodb://localhost/gridfs_test", function (err, db) { 
    "use strict"; 
    gridfs = Grid(db, mongo); 

    // write file 
    writeStream = gridfs.createWriteStream({ filename: "test.txt" }); 
    fs.createReadStream("test.txt").pipe(writeStream); 

    // after the write is finished 
    writeStream.on("close", function() { 
     // read file, buffering data as we go 
     readStream = gridfs.createReadStream({ filename: "test.txt" }); 

     readStream.on("data", function (chunk) { 
      buffer += chunk; 
     }); 

     // dump contents to console when complete 
     readStream.on("end", function() { 
      console.log("contents of file:\n\n", buffer); 
     }); 
    }); 
});

來源

2013-06-15 03:42:28

用node.js，mongoose，gridfs-stream讀取文件

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