如何用jq将对象列表转换为嵌套单对象（Ansible场景）

在Ansible处理大型JSON响应时，因原结构导致搜索速度慢，需要将字典列表转换为单个嵌套字典。Ansible自带的jmespath无法实现值转键，尝试了支持jq的社区插件，但只能硬编码顶层字典。

示例输入JSON #

{
  "json": {
    "@code": "19",
    "@status": "success",
    "result": {
      "@count": "7003",
      "@total-count": "7003",
      "entry": [
        {
          "@location": "shared",
          "@name": "bgp_routers",
          "static": {
            "member": [
              "core-1",
              "core-2",
              "core-3",
              "supercore"
            ]
          }
        },
        {
          "@location": "shared",
          "@name": "web_servers",
          "description": "req-5",
          "static": {
            "member": [
              "web001",
              "web002",
              "web004"
            ]
          }
        },
        {
          "@location": "remote-site-1",
          "@name": "web_servers-2",
          "description": "req-100",
          "static": {
            "member": [
              "web001",
              "web003",
              "web004"
            ]
          }
        }
      ]
    }
  }
}

期望转换后的嵌套结构 #

{
    "shared": {
      "bgp_routers": {
        "@location": "shared",
        "@name": "bgp_routers",
        "static": {
          "member": [
            "core-1",
            "core-2",
            "core-3",
            "supercore"
          ]
        }
      },
      "web_servers": {
        "@location": "shared",
        "@name": "web_servers",
        "description": "req-5",
        "static": {
          "member": [
            "web001",
            "web002",
            "web004"
          ]
        }
      }
    },
    "remote-site-1": {
      "web_servers-2": {
        "@location": "remote-site-1",
        "@name": "web_servers-2",
        "description": "req-100",
        "static": {
          "member": [
            "web001",
            "web003",
            "web004"
          ]
        }
      }
    }
}

当前尝试的问题 #

使用以下jq语句：

.json.result.entry | map({ (.["@location"]):  {( .["@name"] ): . }})

得到的结果无法合并相同的shared键，使用add只会保留最后一个shared条目：

[
  {
    "shared": {
      "bgp_routers": {
        "@location": "shared",
        "@name": "bgp_routers",
        "static": {
          "member": [
            "core-1",
            "core-2",
            "core-3",
            "supercore"
          ]
        }
      }
    }
  },
  {
    "shared": {
      "web_servers": {
        "@location": "shared",
        "@name": "web_servers",
        "description": "req-5",
        "static": {
          "member": [
            "web001",
            "web002",
            "web004"
          ]
        }
      }
    }
  },
  {
    "remote-site-1": {
      "web_servers-2": {
        "@location": "remote-site-1",
        "@name": "web_servers-2",
        "description": "req-100",
        "static": {
          "member": [
            "web001",
            "web003",
            "web004"
          ]
        }
      }
    }
  }
]

另外，不使用Ansible的|combine过滤器是因为处理大循环时性能极低，每次迭代都会删除并重建字典。

解决方案：使用jq的reduce和递归合并操作符 #

要实现相同@location下的条目合并，需用jq的reduce遍历条目，结合递归合并操作符*来合并同位置的字典，替代简单的add。

最终jq语句 #

.json.result.entry | reduce .[] as $item ({}; . * { ($item["@location"]): { ($item["@name"]): $item } })

逻辑解释 #

• reduce .[] as $item ({}; ...)：以空字典为初始值，遍历每个条目$item
• . * { ... }：使用*操作符递归合并当前结果和新生成的条目字典，相同@location下的子字典会被合并而非覆盖
• { ($item["@location"]): { ($item["@name"]): $item } }：为每个条目生成对应嵌套结构，和之前的map逻辑一致，但通过reduce+*实现合并

效果验证 #

执行上述语句后，会直接输出期望的嵌套结构，且处理大型数据集时性能远优于Ansible的combine循环，因为jq的合并操作是原生高效实现的。

内容的提问来源于stack exchange，提问作者MostProductiveAfter6