MongoAggregationResource.java 文件源码

private BasicDBList aggregate(RequestContext ctx) {
    BasicDBList queryObject = new BasicDBList();
    if (ctx.resourceParams() != null && ctx.resourceParams().contains("q")) {
        String queryString = ctx.resourceParams().value("q");
        DBObject paramObject = (DBObject) JSON.parse(queryString);

        if (paramObject instanceof BasicDBList) {
            queryObject = (BasicDBList) paramObject;
        } else {
            queryObject.add(paramObject);
        }
    }

    DBCollection dbCollection = parent().getDBCollection();

    try {
        BasicDBList result = new BasicDBList();
        AggregationOutput output = dbCollection.aggregate(
                (DBObject) queryObject.remove(0),
                queryObject.toArray(new DBObject[queryObject.size()]));
        for (DBObject dbObject : output.results()) {
            result.add(dbObject);
        }

        return result;

    } catch (Exception e) {
        logger().error("", e);
        throw new RuntimeException("Aggregation query failed: ", e);
    }
}