display subdocuments with mongodb and jsp?

Question

Mongodb and JSP :

my code :

---

DBCursor curseur = table.find();

while (curseur.hasNext()) { 
    DBObject ligne = curseur.next();

    out.println(ligne.get("_id")); 
    out.println(ligne.get("joueur")); 
    out.println(ligne.get("equipes"));
    out.println(ligne.get("matchs"));
}

---

the code runs normally but the problem is in the display :

---

_id 1  
Joueur  { "nom" : "De Oliveira" , "prenom" : "Denilson"}  
Equipes [ "Sao Paulo FC" , "Bétis Seville" , "Bordeaux"]  
Matchs  [{ "date_m" : "1996" , "stade" : "Morumbi"}, 
         { "date_m" : "1999" , "stade" : "Benito Villamarn"}, 
         { "date_m" : "2005" , "stade" : "Chaban-Delmas"}]  

---

It's correct but :

1. How can I know the number of columns?

2. How can I access the sub documents?

I want to display a list of data with this structure (without the braces and brackets):

---

id : 1

Joueur : nom : De Oliveira
        prenom : Denilson

Equipes : Sao Paulo FC, Betis Seville, Bordeaux

matchs : date_m : 1996
         stade : Morumbi

         date_m : 1999
         stade : Benito Villamarn

         date_m : 2005
         stade : Chaban-Delmas

---

Thank you in advance for your cooperation !

Answer 1

If you want fetch the data inside an inner array of your document you need store it in a ArrayList or List of java, like this:

cursor = document.find(query);
     if(cursor.hasNext()) {
     ArrayList<?> Matchs = (BasicDBList) cursor.next().get("Matchs");
             /* here you can iterate over Matchs arrayList and get his data */
             for(int i=0; i< Matchs.size(); i++){
                   JsonParser jsonParser = new JsonParser();
                   JsonElement jsonElement = jsonParser.parse(String.valueOf(Matchs.get(i)));

                if (jsonElement.isJsonObject()) {
                   JsonObject jsonObject = jsonElement.getAsJsonObject();
                   String date_m = jsonObject.get("date_m").getAsString();
                   String stade = jsonObject.get("stade").getAsString();
                }
             }
     }

NOTE: You need add to you project a jar of google.gson, to deserialize more easily your bson object

https://code.google.com/p/google-gson/downloads/detail?name=google-gson-2.2.4-release.zip

I hope it helps.

Answer 2

The number of "columns" can fetched using dbObject.size(). Subdocuments are just fields backed by other DBObjects so you fetch them the same way as any other field.