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


                    final DBCollection col = this.getCollection(info[0]);
                    final String pattern = "^" + Pattern.quote(info[1]) + "/";


                    final DBObject query = QueryBuilder.start(getPROP_PATH()).regex(Pattern.compile(pattern)).get();
                    final DBCursor cur = col.find(query);
                    while ( cur.hasNext() ) {
                        final DBObject dbObj = cur.next();
                        final String childPath = info[0] + '/' + dbObj.get(getPROP_PATH());
                        this.deletedResources.add(childPath);
                        this.changedResources.remove(childPath);
                    }
                    deletedResource = true;

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                } else {
                    pattern = "^" + Pattern.quote(info[1]) + "/([^/])*$";
                }


                final DBObject query = QueryBuilder.start(getPROP_PATH()).regex(Pattern.compile(pattern)).get();
                final DBCursor cur = col.find(query).
                        sort(BasicDBObjectBuilder.start(getPROP_PATH(), 1).get());
                return new Iterator<Resource>() {


                    public boolean hasNext() {
                        return cur.hasNext();
                    }


                    public Resource next() {
                        final DBObject obj = cur.next();
                        final String objPath = obj.get(getPROP_PATH()).toString();
                        final int lastSlash = objPath.lastIndexOf('/');
                        final String name;
                        if (lastSlash == -1) {
                            name = objPath;

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        DBCollection col = this.getCollection( collectionName );
        if ( col != null )
        {
            String criteria = query.trim().substring( query.indexOf( ".find(" ) + 6, query.length() - 1 );
            DBObject dbObject = (DBObject) JSON.parse( criteria );
            final DBCursor cur = col.find( dbObject );
            final String rootPath = context.getRootWithSlash();
            
            return new Iterator<Resource>() {


                public boolean hasNext() {
                    return cur.hasNext();
                }


                public Resource next() {
                    final DBObject obj = cur.next();
                    final String objPath = obj.get(getPROP_PATH()).toString();
                    final int lastSlash = objPath.lastIndexOf('/');
                    final String name;
                    if (lastSlash == -1) {
                        name = objPath;

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    if (exchange.isInIoThread()) {
      exchange.dispatch(this);
      return;
    }
    List<Fortune> fortunes = new ArrayList<>();
    DBCursor cursor = database.getCollection("Fortune").find();
    while (cursor.hasNext()) {
      DBObject object = cursor.next();
      fortunes.add(new Fortune(
          ((Number) object.get("_id")).intValue(),
          (String) object.get("message")));
    }
    fortunes.add(new Fortune(0, "Additional fortune added at request time."));

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  public long getNumberOfEmbeddedAssociations(SessionFactory sessionFactory) {
    DB db = getProvider( sessionFactory ).getDatabase();
    long associationCount = 0;


    for ( String entityCollection : getEntityCollections( sessionFactory ) ) {
      DBCursor entities = db.getCollection( entityCollection ).find();


      while ( entities.hasNext() ) {
        DBObject entity = entities.next();
        associationCount += getNumberOfEmbeddedAssociations( entity );
      }
    }


    return associationCount;

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    return parseResult.resultValue.build();
  }


  private ClosableIterator<Tuple> doFind(MongoDBQueryDescriptor query, QueryParameters queryParameters, DBCollection collection,
      EntityKeyMetadata entityKeyMetadata) {
    DBCursor cursor = collection.find( query.getCriteria(), query.getProjection() );


    if ( query.getOrderBy() != null ) {
      cursor.sort( query.getOrderBy() );
    }


    // apply firstRow/maxRows if present
    if ( queryParameters.getRowSelection().getFirstRow() != null ) {
      cursor.skip( queryParameters.getRowSelection().getFirstRow() );
    }


    if ( queryParameters.getRowSelection().getMaxRows() != null ) {
      cursor.limit( queryParameters.getRowSelection().getMaxRows() );
    }


    return new MongoDBResultsCursor( cursor, entityKeyMetadata );
  }

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        if (after != -1) {
            obj.add(new BasicDBObject("$gt",  new BasicDBObject("$gt", new Date(after))));
        }
        andQuery.put("$and", obj);


        final DBCursor cursor = mongoConnection.getDatabase().getCollection("graylog2_metrics")
                .find(andQuery).sort(new BasicDBObject("timestamp", 1));
        Map<String, Object> metricsData = Maps.newHashMap();
        metricsData.put("name", metricName);
        List<Object> values = Lists.newArrayList();
        metricsData.put("values", values);


        while (cursor.hasNext()) {
            final DBObject value = cursor.next();
            metricsData.put("node", value.get("node"));


            final MetricType metricType = MetricType.valueOf(((String) value.get("type")).toUpperCase());
            Map<String, Object> dataPoint = Maps.newHashMap();
            values.add(dataPoint);

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            filter = FrameworkUtil.createFilter(filterValue);
        }


        DBCollection coll = getCollection();


        DBCursor cursor = coll.find();
        try {
            while (cursor.hasNext()) {
                // Hmm, there might be a more clever way of doing this...
                Role role = m_helper.deserialize(cursor.next());
                if ((filter == null) || filter.match(role.getProperties())) {
                    roles.add(role);
                }
            }
        } finally {
            cursor.close();
        }


        return roles.toArray(new Role[roles.size()]);
    }

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    @Override
    public Role getRole(String name) {
        DBCollection coll = getCollection();


        DBCursor cursor = coll.find(getTemplateObject(name));
        try {
            if (cursor.hasNext()) {
                return m_helper.deserialize(cursor.next());
            }
        } finally {
            cursor.close();
        }


        return null;
    }

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        // get the batch size and number to skip
        Integer batchSize = exchange.getIn().getHeader(MongoDbConstants.BATCH_SIZE, Integer.class);
        Integer numToSkip = exchange.getIn().getHeader(MongoDbConstants.NUM_TO_SKIP, Integer.class);
        Integer limit = exchange.getIn().getHeader(MongoDbConstants.LIMIT, Integer.class);
        DBObject sortBy = exchange.getIn().getHeader(MongoDbConstants.SORT_BY, DBObject.class);
        DBCursor ret = null;
        try {
            if (query == null && fieldFilter == null) {
                ret = dbCol.find(new BasicDBObject());
            } else if (fieldFilter == null) {
                ret = dbCol.find(query);
            } else {
                ret = dbCol.find(query, fieldFilter);
            }


            if (sortBy != null) {
                ret.sort(sortBy);
            }


            if (batchSize != null) {
                ret.batchSize(batchSize.intValue());
            }


            if (numToSkip != null) {
                ret.skip(numToSkip.intValue());
            }


            if (limit != null) {
                ret.limit(limit.intValue());
            }


            Message resultMessage = prepareResponseMessage(exchange, MongoDbOperation.findAll);
            resultMessage.setBody(ret.toArray());
            resultMessage.setHeader(MongoDbConstants.RESULT_TOTAL_SIZE, ret.count());
            resultMessage.setHeader(MongoDbConstants.RESULT_PAGE_SIZE, ret.size());
        } finally {
            // make sure the cursor is closed
            if (ret != null) {
                ret.close();
            }
        }


    }

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