Java Spring Data中的MongoDB $graphlookup

Question

我正在寻找一种在Resful Web API中使用Java实现图形查找的方法。我正在尝试实现类似于MongoDB (https://docs.mongodb.com/v3.4/reference/operator/aggregation/graphLookup/)的层次结构

    { "_id" : 1, "name" : "Dev" }
    { "_id" : 2, "name" : "Eliot", "reportsTo" : "Dev" }
    { "_id" : 3, "name" : "Ron", "reportsTo" : "Eliot" }
    { "_id" : 4, "name" : "Andrew", "reportsTo" : "Eliot" }
    { "_id" : 5, "name" : "Asya", "reportsTo" : "Ron" }
    { "_id" : 6, "name" : "Dan", "reportsTo" : "Andrew" }

这是employee集合，我想要的是能够创建存储在MongoDB中的结构

 {
   "_id" : 1,
   "name" : "Dev",
   "reportingHierarchy" : [ ]
}
{
   "_id" : 2,
   "name" : "Eliot",
   "reportsTo" : "Dev",
   "reportingHierarchy" : [
      { "_id" : 1, "name" : "Dev" }
   ]
}
{
   "_id" : 3,
   "name" : "Ron",
   "reportsTo" : "Eliot",
   "reportingHierarchy" : [
      { "_id" : 1, "name" : "Dev" },
      { "_id" : 2, "name" : "Eliot", "reportsTo" : "Dev" }
   ]
}

我见过这样的聚合示例，但在graphlookup上还没有

Aggregation agg = newAggregation(
        match(Criteria.where("pageId").is("2210")),
        unwind("postIds"),
        group("_id").sum("1").as("sum")
        //project("$sum").and("pageId").previousOperation()
    );

有没有办法把graphlookup转换成这样的格式？而不是使用match，unwind，group，我可以使用GraphLookupOperation，然后使用get map result。

Answer 1

AggregationOperation aggregationOperation = new AggregationOperation() {
        @Override public DBObject toDBObject(AggregationOperationContext aggregationOperationContext) {
            DBObject graphLookup = new BasicDBObject(
                    "from", "individual").append(
                    "startWith", "$reportsTo").append(
                    "connectFromField", "reportsTo").append(
                    "connectToField", "firstName").append(
                    "maxDepth", 2).append(
                    "as", "reportingHierarchy");
            return new BasicDBObject("$graphLookup", graphLookup);

这段代码考虑到了一个变通方法，因为我使用的是较老的版本，我认为是1.10.0 spring mongo。现在我遇到了"reportingHierarchy“看起来不像我想要的问题。它没有给我一个名字。只有reportsTo和reportingHierarchy，也包括我不想要的_class。