MongoTemplate聚合返回“IllegalArgumentException：无效引用”

Question

给定具有以下文档的集合：

{
    "_id": {
        "$oid": "5e8f83289d3a48132e9b6e34"
    },
    "resource-id": "my-default-network-map",
    "uri": "http://alto.example.com/networkmap",
    "mappings": [
       {
        "version-tag": "X",
        "address-aggregations": [{
            "pid": "PID1",
            "ipv4-addresses": ["192.0.2.0/24", "198.51.100.0/25"]
        }, {
            "pid": "PID2",
            "ipv4-addresses": ["198.51.100.128/25"]
        }, {
            "pid": "PID3",
            "ipv4-addresses": ["0.0.0.0/0"],
            "ipv6-addresses": ["::/0"]
        }]
       }, 
       {
        "version-tag": "Y",
        "address-aggregations": [{
            "pid": "PID1",
            "ipv4-addresses": ["192.0.2.0/24", "198.51.100.0/25"]
        }, {
            "pid": "PID2",
            "ipv4-addresses": ["198.51.100.128/25"]
        }]
       }],
    "_class": "com.example.restservice.entity.NetworkMapEntity"
}

假设有更多的这些文档带有其他“resource-id”值，我希望返回我之前键入的同一个文档，但是“mappings”数组只包含version-tag=X的对象，“address-aggregations”数组只包含[pidx,pidy,...]中带有“pid”的对象。我目前能想到的最好的方法是以下聚合管道：

[
  {
    '$match': {
      'resource-id': 'my-default-network-map'
    }
  }, {
    '$unwind': {
      'path': '$mappings'
    }
  }, {
    '$match': {
      'mappings.version-tag': 'X'
    }
  }, {
    '$unwind': {
      'path': '$mappings.address-aggregations'
    }
  }, {
    '$match': {
      'mappings.address-aggregations.pid': {
        '$in': [
          'PID1', 'PID2'
        ]
      }
    }
  }, {
    '$group': {
      '_id': '$_id', 
      'resource-id': {
        '$first': '$resource-id'
      }, 
      'uri': {
        '$first': '$uri'
      }, 
      'version-tag': {
        '$first': '$mappings.version-tag'
      }, 
      'address-aggregations': {
        '$push': '$mappings.address-aggregations'
      }
    }
  }, {
    '$project': {
      '_id': 1, 
      'resource-id': 1, 
      'uri': 1, 
      'mappings.version-tag': '$version-tag', 
      'mappings.address-aggregations': '$address-aggregations'
    }
  }, {
    '$group': {
      '_id': '$_id', 
      'resource-id': {
        '$first': '$resource-id'
      }, 
      'uri': {
        '$first': '$uri'
      }, 
      'mappings': {
        '$push': '$mappings'
      }
    }
  }
]

它在mongodb客户端shell上返回了预期的结果。但是，当我将此类对象转换为带有聚合对象的MongoTemplate查询时：

Aggregation aggregation = newAggregation(
  match(Criteria.where("resource-id").is(resourceId)),
  unwind("mappings"),
  match(Criteria.where("mappings.version-tag").is(versionTag)),
  unwind("mappings.address-aggregations"),
  match(Criteria.where("mappings.address-aggregations.pid").in(pids)),
  group("$_id")
    .first("resource-id").as("resource-id")
    .first("uri").as("uri")
    .first("mappings.version-tag").as("version-tag")
    .push("mappings.address-aggregations").as("address-aggregations"),
  project("_id", "resource-id", "uri")
    .and("version-tag").as("mappings.version-tag")
    .and("address-aggregations").as("mappings.address-aggregations"),
  group("_id")
    .first("resource-id").as("resource-id")
    .first("uri").as("uri")
    .push("mappings").as("mappings")
);


AggregationResults<NetworkMapEntity> aggregationResults = mongoTemplate.aggregate(aggregation, "NetworkMaps", NetworkMapEntity.class);

并对其进行测试，则引发以下异常:java.lang.IllegalArgumentException：无效引用'mappings'！

搜索了一下，我发现有类似问题的人说这是SpringFramework.data依赖项的一个bug，但是是一年以前的版本，所以我认为我构造聚合对象可能是问题所在。我是不是在解决方案的Java代码部分做错了什么？

Answer 1

虽然我仍然不明白为什么当前的解决方案不起作用，并且希望了解为什么不起作用，但我将查询更改如下，并且现在似乎可以按预期工作：

Aggregation aggregation = newAggregation(
  match(Criteria.where("resource-id").is(resourceId)),
  unwind("mappings"),
  match(Criteria.where("mappings.version-tag").is(versionTag)),
  unwind("mappings.address-aggregations"),
  match(Criteria.where("mappings.address-aggregations.pid").in(pids)),
  group("_id", "resource-id", "uri")
    .first("mappings.version-tag").as("version-tag")
    .push("mappings.address-aggregations").as("address-aggregations")
  group("_id._id")
    .first("_id.resource-id").as("resource-id")
    .push(
       new BasicDBObject("version-tag", "$version-tag")
             .append("address-aggregations", "$address-aggregations")).as("mappings")
);