Elasticsearch嵌套聚合桶中bucket_selector不生效问题咨询

你当前的写法报错核心原因是bucket_selector的层级和引用的聚合路径不符合要求：
你把filtered_product_quantity和unique_product平级放置，而unique_product是terms聚合，返回的是多桶数组，你通过unique_product.key和unique_product>quantity拿到的是数组对象，不是bucket_selector要求的单值数值，因此触发报错。
同时你原脚本存在类型不匹配隐患：product.id是数值类型，而你参数requiredQuantities的key是字符串类型，直接取值会拿不到对应配置。

根据你的需求，分两种常见场景提供写法：

场景1：过滤每个product.id对应的子桶，仅保留满足数量要求的product记录 #

把bucket_selector放到unique_product的子聚合层级，此时每个桶对应单个product.id，能拿到单值的key和sum结果：

GET _search
{
  "size": 0,
  "query": {
    "bool": {
      "must": [
        {
          "terms": {
            "product.id": [20,21,22,23,24]
          }
        }
      ]
    }
  },
  "aggs": {
    "carts": {
      "terms": {
        "field": "item.cart_key"
      },
      "aggs": {
        "unique_product": {
          "terms": {
            "field": "product.id"
          },
          "aggs": {
            "quantity": {
              "sum": {
                "field": "item.quantity"
              }
            },
            "filtered_product": {
              "bucket_selector": {
                "buckets_path": {
                  "productId": "_key",
                  "productQuantity": "quantity"
                },
                "script": {
                  "params": {
                    "requiredQuantities": {
                      "20": null,
                      "21": null,
                      "22": null,
                      "23": 3,
                      "24": null
                    }
                  },
                  "lang": "painless",
                  "source": """
                    def minQty = params.requiredQuantities[params.productId.toString()];
                    // 没有设置最小数量的product直接保留，设置了的需要满足数量要求
                    return minQty == null || params.productQuantity >= minQty;
                  """
                }
              }
            }
          }
        }
      }
    }
  }
}

场景2：过滤整个cart_key桶，仅保留所有指定product都满足数量要求的购物车 #

如果你需要的是只留下完全满足所有数量要求的购物车，那需要先对每个指定的product.id单独做sum聚合，再统一判断：

GET _search
{
  "size": 0,
  "query": {
    "bool": {
      "must": [
        {
          "terms": {
            "product.id": [20,21,22,23,24]
          }
        }
      ]
    }
  },
  "aggs": {
    "carts": {
      "terms": {
        "field": "item.cart_key"
      },
      "aggs": {
        "sum_p20": {
          "filter": {"term": {"product.id": 20}},
          "aggs": {"qty": {"sum": {"field": "item.quantity"}}}
        },
        "sum_p21": {
          "filter": {"term": {"product.id": 21}},
          "aggs": {"qty": {"sum": {"field": "item.quantity"}}}
        },
        "sum_p22": {
          "filter": {"term": {"product.id": 22}},
          "aggs": {"qty": {"sum": {"field": "item.quantity"}}}
        },
        "sum_p23": {
          "filter": {"term": {"product.id": 23}},
          "aggs": {"qty": {"sum": {"field": "item.quantity"}}}
        },
        "sum_p24": {
          "filter": {"term": {"product.id": 24}},
          "aggs": {"qty": {"sum": {"field": "item.quantity"}}}
        },
        "filter_cart": {
          "bucket_selector": {
            "buckets_path": {
              "p20": "sum_p20>qty",
              "p21": "sum_p21>qty",
              "p22": "sum_p22>qty",
              "p23": "sum_p23>qty",
              "p24": "sum_p24>qty"
            },
            "script": {
              "params": {
                "requiredQuantities": {
                  "20": null,
                  "21": null,
                  "22": null,
                  "23": 3,
                  "24": null
                }
              },
              "source": """
                def check(id, qty) {
                  def min = params.requiredQuantities[id];
                  return min == null || qty >= min;
                }
                return check("20", params.p20) && check("21", params.p21) && check("22", params.p22) && check("23", params.p23) && check("24", params.p24);
              """
            }
          }
        }
      }
    }
  }
}

内容的提问来源于stack exchange，提问作者Toto NaBendo