在MongoDB中的对象内插入数组 [英] Insert Array inside an object in MongoDB

问题描述

我是MongoDB的新手，我想将这样的数据插入到mongodb中，但是我不知道怎么做

I am new at MongoDB and I want to insert to mongodb data like this but I couldn't figure out how

{
  image = "cab"
  tags = [
            [ "NNP", 0 ],
            [ "NN", 1 ]
         ]
},
{
  image = "castle"
  tags = [
            [ "NNP", 2 ],
            [ "NN", 1 ],
         ]
}

我的代码是

    BasicDBObject obj = new BasicDBObject();
    obj.put("images", ....);
    for(Tag tag:tags){
    BasicDBObject tagsObj = new BasicDBObject();
    tagsObj.put("NNP",tag.getNNP());
    tagsObj.put("NN",tag.getNN());
    obj.put("tags",tagsObj);

    }

更新: 使用此代码

Mongo m = new Mongo();
DB db = m.getDB("test");
DBCollection coll = db.getCollection("tags");
for(Tag tag:tags){
    BasicDBList dbl = new BasicDBList();
    dbl.add(new BasicDBObject("NNP",tag.getNNP()));
    dbl.add(new BasicDBObject("NN", tag.getNNP()));
    BasicDBObject outer=new BasicDBObject("images", currentImageName).append("tags", dbl);
    coll.insert(outer);
                }

我只存储每张图片，因为同一张图片的标签可能像这样

I store every image alone cause the tags might be like this for the same image

  {
      image = "cab",
      tags = [
                { "NNP", 0 },
                { "NN", 1 }
             ],
             [  {"NNP", 4 },
                { "NN", 5 } 
             ],
             [
                {"NNP", 0 },
                { "NN", 4 }
             ]

}，

谢谢

推荐答案

基本上，将BasicDBObject用于键-值映射，将BasicDBList用于数组对象.对于您问题中的对象，您可以这样做:

Basically you use BasicDBObject for key-value mappings and BasicDBList for array objects. For the object in your question, you'd do this:

BasicDBList dbl = new BasicDBList();
dbl.add(new BasicDBObject("NNP",0));
dbl.add(new BasicDBObject("NN", 1));
BasicDBOBject outer=new BasicDBObject("image", "cab").append("tags", dbl);

api中有一些便捷的方法，可以使此操作不再那么冗长.

There's some convenience methods in the api to make this a bit less verbose.

映射如下:

for:  {"A":1}  use: new BasicDBObject("A",1)
for: {"A":1, "B":2}  use: new BasicDBObject("A",1).append("B",2)
for: {"A":{"B":2}}  use: new BasicDBObject("A",new BasicDBObject("B",2))
for: {"A":["B","C"]} use:
        BasicDBList dbl = new BasicDBList();
        dbl.add("B");
        dbl.add("C");
         ->  new BasicDBObject("A",dbl);

这篇关于在MongoDB中的对象内插入数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！