MongoDao.java 文件源码

/**
 * 最小统计
 *
 * @param collectionName
 * @param match
 * @param minField
 * @return
 */
public Object min(String collectionName, Document match, String minField) {
    AggregateIterable<Document> aggregate = getDB().getCollection(collectionName).aggregate(
            Arrays.asList(
                    match(match)
                    , group(null, Accumulators.min("_min", "$" + minField))
            )
    );
    Document first = aggregate.first();
    if (first != null) {
        return first.get("_min");
    }
    return null;
}