Examples of com.mongodb.DBCursor

com.mongodb.DBCursor
An iterator over database results. Doing a find() query on a collection returns a DBCursor thus
```
 DBCursor cursor = collection.find( query ); if( cursor.hasNext() ) DBObject obj = cursor.next(); 
```
Warning: Calling toArray or length on a DBCursor will irrevocably turn it into an array. This means that, if the cursor was iterating over ten million results (which it was lazily fetching from the database), suddenly there will be a ten-million element array in memory. Before converting to an array, make sure that there are a reasonable number of results using skip() and limit().
For example, to get an array of the 1000-1100th elements of a cursor, use
```
 List obj = collection.find( query ).skip( 1000 ).limit( 100 ).toArray(); 
```
@dochub cursors

   */
  @Override
  public void refresh(Collection<Refreshable> alreadyRefreshed) {
    BasicDBObject query = new BasicDBObject();
    query.put("deleted_at", new BasicDBObject("$gt", mongoTimestamp));
    DBCursor cursor = collection.find(query);
    Date ts = new Date(0);
    while (cursor.hasNext()) {
      Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
      String userID = getID(user.get(mongoUserID), true);
      Collection<List<String>> items = Lists.newArrayList();
      List<String> item = Lists.newArrayList();
      item.add(getID(user.get(mongoItemID), false));
      item.add(Float.toString(getPreference(user.get(mongoPreference))));
      items.add(item);
      try {
        refreshData(userID, items, false);
      } catch (NoSuchUserException e) {
        log.warn("No such user ID: {}", userID);
      } catch (NoSuchItemException e) {
        log.warn("No such items: {}", items);
      }
      if (ts.compareTo(getDate(user.get("created_at"))) < 0) {
        ts = getDate(user.get("created_at"));
      }
    }
    query = new BasicDBObject();
    query.put("created_at", new BasicDBObject("$gt", mongoTimestamp));
    cursor = collection.find(query);
    while (cursor.hasNext()) {
      Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
      if (!user.containsKey("deleted_at")) {
        String userID = getID(user.get(mongoUserID), true);
        Collection<List<String>> items = Lists.newArrayList();
        List<String> item = Lists.newArrayList();
        item.add(getID(user.get(mongoItemID), false));

View Full Code Here

      collectionMap.ensureIndex(indexObj);
      indexObj = new BasicDBObject();
      indexObj.put("long_value", 1);
      collectionMap.ensureIndex(indexObj);
      collectionMap.remove(new BasicDBObject());
      DBCursor cursor = collection.find();
      while (cursor.hasNext()) {
        Map<String,Object> user = (Map<String,Object>) cursor.next().toMap();
        if (!user.containsKey("deleted_at")) {
          long userID = Long.parseLong(fromIdToLong(getID(user.get(mongoUserID), true), true));
          long itemID = Long.parseLong(fromIdToLong(getID(user.get(mongoItemID), false), false));
          float ratingValue = getPreference(user.get(mongoPreference));
          Collection<Preference> userPrefs = userIDPrefMap.get(userID);

View Full Code Here

            );
        }


        QueryBuilder builder = QueryBuilder.start("start.x").greaterThan(50);


        DBCursor cursor = lines.find(builder.get(),
                new BasicDBObject("start.y", true).append("_id", false));


        try {
            while (cursor.hasNext()) {
                DBObject cur = cursor.next();
                System.out.println(cur);
            }
        } finally {
            cursor.close();
        }
    }

View Full Code Here

        DB db = client.getDB("course");
        return db.getCollection("FindModifyTest");
    }


    private static void printCollection(final DBCollection collection) {
        DBCursor cursor = collection.find().sort(new BasicDBObject("_id", 1));
        try {
            while (cursor.hasNext()) {
                System.out.println(cursor.next());
            }
        } finally {
            cursor.close();
        }


    }

View Full Code Here

        collection.drop();
        return collection;
    }


    private static void printCollection(final DBCollection collection) {
        DBCursor cursor = collection.find().sort(new BasicDBObject("_id", 1));
        try {
            while (cursor.hasNext()) {
                System.out.println(cursor.next());
            }
        } finally {
            cursor.close();
        }


    }

View Full Code Here

        }


        DBObject query = QueryBuilder.start("x").is(0)
                .and("y").greaterThan(10).lessThan(70).get();


        DBCursor cursor = collection.find(query,
                new BasicDBObject("y", true).append("_id", false));
        try {
            while (cursor.hasNext()) {
                DBObject cur = cursor.next();
                System.out.println(cur);
            }
        } finally {
            cursor.close();
        }
    }

View Full Code Here

        System.out.println("Find one:");
        DBObject one = collection.findOne();
        System.out.println(one);


        System.out.println("\nFind all: ");
        DBCursor cursor = collection.find();
        try {
          while (cursor.hasNext()) {
              DBObject cur = cursor.next();
              System.out.println(cur);
          }
        } finally {
            cursor.close();
        }


        System.out.println("\nCount:");
        long count = collection.count();
        System.out.println(count);

View Full Code Here

        System.out.println("\nCount:");
        long count = collection.count(builder.get());
        System.out.println(count);


        System.out.println("\nFind all: ");
        DBCursor cursor = collection.find(builder.get());
        try {
            while (cursor.hasNext()) {
                DBObject cur = cursor.next();
                System.out.println(cur);
            }
        } finally {
            cursor.close();
        }
    }

View Full Code Here

                                              .append("y", rand.nextInt(90) + 10)
                            )
            );
        }


        DBCursor cursor = lines.find()
                .sort(new BasicDBObject("start.x", 1).append("start.y", -1))
                .skip(2).limit(10);


        try {
            while (cursor.hasNext()) {
                DBObject cur = cursor.next();
                System.out.println(cur);
            }
        } finally {
            cursor.close();
        }
    }

View Full Code Here


        long count = collection.count(query);
        System.out.println(count);


        System.out.println("\nFind all: ");
        DBCursor cursor = collection.find(query)
                                    .sort(new BasicDBObject("student_id", 1).append("score", 1));


        //scratch(collection);
        int prevStudentId = -1;
        while (cursor.hasNext()) {
            DBObject cur = cursor.next();
            if((Integer) cur.get("student_id") > prevStudentId) {
                collection.remove(new BasicDBObject("_id",cur.get("_id")));
                System.out.print("Borra "+cur.get("_id")+"\n");
            }
            prevStudentId = (Integer) cur.get("student_id");

View Full Code Here

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