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 ],
]
}
my code is
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);
}
UPDATE: using this code
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);
}
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 }
]
},
Thanks
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);
There's some convenience methods in the api to make this a bit less verbose.
The mapping works like this:
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);
Did you mean like this?
BasicDBObject obj = new BasicDBObject();
obj.put("image", ....);
for(Tag tag:tags){
BasicDBObject tagsObj = new BasicDBObject();
tagsObj.put("NNP",tag.getNNP());
tagsObj.put("NN",tag.getNN());
obj.put("tags",tagsObj);
}
Here is how i use it when using mongo3.x:
suppose you want the result to be like this: {"data": [{"key":"v1"}, {"key":"v1"}, {"key":"v1"}] }
[step1]: use Java Map to create json object which maps to the elements inside the array; that is, the {} inside []
[step1 Ans]: Map m1,m2,m3 = new HashMap(); m1.put("key", "v1"); m2.put("key", "v1"); m3.put("key", "v1");
Map m1,m2,m3 = new HashMap(); m1.put("key", "v1"); m2.put("key", "v1"); m3.put("key", "v1");
[step2]: use Java List to add all Java Map into one element.
[step2 Ans]: List list = new ArrayList(); list.add(m1); list.add(m2); list.add(m3);
List list = new ArrayList(); list.add(m1); list.add(m2); list.add(m3);
[step3]: add Java list into mongo
[step3 Ans]: Document dc = new Document("key", list);
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