帶CSV數據的MongoDB

Question

我正在編寫一個應用程序，其中輸入的數據源是CSV格式。我需要在數據庫上執行CRUD操作。因爲我覺得它適合我的需要，所以我打算去MongoDB。我的問題是 1.如何將CSV數據存儲在MongoDB中？ 2.我是否需要將CSV解析爲json？ 3.我想在UI上顯示數據，那麼MongoDB能以json格式檢索數據嗎？

請幫助我，因爲我是MongoDB的新手。

問候， 普拉迪普

Answer 1

直接在MongoDB中存儲的CSV作爲字符串將是一個非常糟糕的主意，因爲這將是不切實際的操作，並在該格式查詢數據，所以你會希望將其轉換到JSON（實際上是BSON）文檔，因爲您將它添加到MongoDB中。

如果是一次性將CSV數據導入到MongoDB中，那麼您可以使用mongoimport實用程序來執行此操作。否則，您需要在處理CSV輸入數據的代碼中進行轉換。

Answer 2

使用Java

Grid FS將文件存儲在兩個集合：

• bucketName.chunks（GridFS的劃分文件成塊，從而被存儲爲塊集合 不同的文件）
• bucketName.files GridFS存儲有關文件集合中存儲文件的信息。 每個存儲的文件將有一個文件收集文件。

要檢索存儲的文件，GridFS會查找並返回其所有組件塊。

商店csv文件到的MongoDB通過使用GridFS

public static void main(String[] args) throws IOException { 
    mongoDB_GRIDFS("D:\\Yash\\JavaCSV.csv"); 
} 
public static void mongoDB_GRIDFS(String csvlocation) throws IOException{ 
    Mongo Mongo = new Mongo("localhost" , 27017); // Connect to MongoDB 
    DB db = Mongo.getDB("DBName"); // Get database 
    String bucketName = "BucketName"; 
    GridFS gridFs = new GridFS(db,bucketName); //Create instance of GridFS implementation 
    String imageName = "image1"; 
     //upload(gridFs, inputcsvlocation); 
     //download(gridFs, imageName); 
     //delete(gridFs, imageName);   
    Mongo.close(); 
} 
public static void upload(GridFS gridFs, String csvlocation, String imageName) throws IOException{ 
    GridFSInputFile gridFsInputFile = gridFs.createFile(new File(csvlocation)); 
    gridFsInputFile.setId("777"); 
    gridFsInputFile.setFilename(imageName); //Set a name on GridFS entry 
    gridFsInputFile.save(); //Save the file to MongoDB 
} 
public static void download(GridFS gridFs, String imageName) throws IOException{ 
    GridFSDBFile outputImageFile = gridFs.findOne(imageName); 
    String outcsvLocation = "D:\\Yash\\mongoCSV.csv";//Location of the file read from MongoDB to be written 
    outputImageFile.writeTo(new File(outcsvLocation)); 
} 
public static void delete(GridFS gridFs, String imageName){ 
    gridFs.remove(gridFs.findOne(imageName)); 
} 

轉換CSV數據到JSON（或）JSON到csv

public static void main(String myHelpers[]) throws ParseException, IOException{ 
    String jsonString = "{'csvdata': [{'field1': 11,'field2': 12,'field3': 13},{'field1': 21,'field2': 22,'field3': 23},{'field1': 31,'field2': 32,'field3': 33}]}"; 

    Json2Csv("D:\\Yash\\JavaCSV.csv", jsonString); 
    csv2Josn("D:\\Yash\\JavaCSV.csv"); 
} 
@SuppressWarnings("unchecked") 
public static void csv2Josn(String fileName) throws IOException{ 
    BufferedReader csv = new BufferedReader(new FileReader(new File(fileName))); 
    JSONObject obj = new JSONObject(); 
    JSONArray csvFields = new JSONArray(); 
    String csvRow = "", keys = ""; 
    int rowscount = 0; 
    while((csvRow = csv.readLine()) != null){ 
     String[] data = csvRow.split(","); 
     if (rowscount == 0) keys = csvRow; 
     else if(data.length == keys.split(",").length){ 
      JSONObject fieldobj = new JSONObject(); 
      for (int i = 0; i < data.length; i++) fieldobj.put(keys.split(",")[i], data[i]); 
      csvFields.add(fieldobj); 
     } 
     rowscount++; 
    } 
    obj.put("scvdata", csvFields); 
    System.out.println("Final Object : "+obj); 
} 
public static void Json2Csv(String fileName, String jsonString) throws IOException, ParseException{ 
    JSONParser jparser = new JSONParser();  
    jsonString = jsonString.replace("'", "\""); 
    java.io.FileWriter writer = new FileWriter(fileName); 
     JSONObject output = (org.json.simple.JSONObject) jparser.parse(jsonString); 
     JSONArray csvdata = (org.json.simple.JSONArray) output.get("csvdata"); 
     String[] orderdkeys = {"field1", "field2", "field3"}; // JSONObject = HashMap (unorered) 
     writer.append(orderdkeys[0]+","+orderdkeys[1]+","+orderdkeys[2]+"\n"); 
     for (int i = 0; i < csvdata.size(); i++) { 
      JSONObject row = (JSONObject) csvdata.get(i); 
      StringBuffer rowdata= new StringBuffer(); 
      if (orderdkeys.length == row.size()) 
      for (int j = 0; j < row.size(); j++) { 
       rowdata.append(row.get(orderdkeys[j])); 
       if (j+1 < row.size()) rowdata.append(","); 
      } 
      writer.append(rowdata.append("\n").toString()); 
     } 
     writer.flush();   writer.close(); 
}