Java tutorial
/* * Copyright (c) 2011 Jeppetto and Jonathan Thompson * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.iternine.jeppetto.dao.mongodb.projections; import com.mongodb.BasicDBObject; import com.mongodb.DBObject; /** * Counts documents which have a value for a given field. */ class CountCommand extends RowCountCommand { //------------------------------------------------------------- // Methods - Private - Static //------------------------------------------------------------- private static DBObject addFieldExistsCriterion(DBObject query, String field) { return new BasicDBObject(query.toMap()).append(field, new BasicDBObject("$exists", true)); } //------------------------------------------------------------- // Constructor //------------------------------------------------------------- public CountCommand(DBObject query, String field) { super(addFieldExistsCriterion(query, field)); } }