IBM Watson 对话：如何从上下文变量访问 JSON 对象？

Question

我制作了一个聊天机器人，它将 'place' 作为输入并连接到外部 API 服务，将 'place' 作为参数传递。 API 服务 returns 给定地点的所有可用机场详细信息的列表作为 JSON 对象。

例如，如果 'Berlin' 作为对话中的输入，API returns 跟随 JSON 对象，然后存储在上下文变量 $TheResult 中, 当输入为 'Berlin'、

时，上下文变量 $TheResult 保存以下 JSON 对象作为值

{
  "message": {
    "Places": [
      {
        "CityId": "BERL-sky",
        "CountryId": "DE-sky",
        "CountryName": "Germany",
        "PlaceId": "BERL-sky",
        "PlaceName": "Berlin",
        "RegionId": ""
      },
      {
        "CityId": "BERL-sky",
        "CountryId": "DE-sky",
        "CountryName": "Germany",
        "PlaceId": "TXL-sky",
        "PlaceName": "Berlin Tegel",
        "RegionId": ""
      },
      {
        "CityId": "BERL-sky",
        "CountryId": "DE-sky",
        "CountryName": "Germany",
        "PlaceId": "SXF-sky",
        "PlaceName": "Berlin Schoenefeld",
        "RegionId": ""
      },
      {
        "CityId": "BTVA-sky",
        "CountryId": "US-sky",
        "CountryName": "United States",
        "PlaceId": "BTV-sky",
        "PlaceName": "Burlington",
        "RegionId": "VT"
      },
      {
        "CityId": "BLIA-sky",
        "CountryId": "US-sky",
        "CountryName": "United States",
        "PlaceId": "BLI-sky",
        "PlaceName": "Bellingham",
        "RegionId": "WA"
      },
      {
        "CityId": "BRLA-sky",
        "CountryId": "US-sky",
        "CountryName": "United States",
        "PlaceId": "BRL-sky",
        "PlaceName": "Burlington",
        "RegionId": "IA"
      }
    ]
  },
  "parameters": {
    "context": "",
    "message": "",
    "service": "https://skyscanner-skyscanner-flight-search-v1.p.rapidapi.com/apiservices/autosuggest/v1.0/FI/EUR/en-US/?query=Berlin"
  }
}

当我将响应文本用作 Response from external server: $TheResult.message.Places 时，它会生成以下输出

Response from external server: [{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"BERL-sky","PlaceName":"Berlin","RegionId":""},{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"TXL-sky","PlaceName":"Berlin Tegel","RegionId":""},{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"SXF-sky","PlaceName":"Berlin Schoenefeld","RegionId":""},{"CityId":"BTVA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BTV-sky","PlaceName":"Burlington","RegionId":"VT"},{"CityId":"BLIA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BLI-sky","PlaceName":"Bellingham","RegionId":"WA"},{"CityId":"BRLA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BRL-sky","PlaceName":"Burlington","RegionId":"IA"}]

我必须从 JSON 对象访问第一个 'CityId' 并将其显示为输出，在柏林作为输入的情况下，预期输出是，

The first airport city id is: BERL-sky

我尝试了回复文本，The first airport city id is: $TheResult.message.Places.CityId 它抛出以下对话节点错误

Error when updating output with output of dialog node id [node_1_1551877430730]. Node output is [{"generic":[{"values":[{"text":"Response from external server: $TheResult.message.Places.CityId"}],"response_type":"text","selection_policy":"sequential"}]}] SpEL evaluation error: Expression [ $TheResult.message.Places.CityId ] converted to [ context['TheResult'].message.Places.CityId ] at position 37: EL1008E: Property or field 'CityId' cannot be found on object of type 'JsonArray' - maybe not public?

和回复文本，The first airport city id is: $TheResult.message.Places[0].CityId 也没有用。它没有产生任何错误，但显示与上面相同的输出，只是在末尾附加了额外的 [0].CityId。

The first airport city id is: [{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"BERL-sky","PlaceName":"Berlin","RegionId":""},{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"TXL-sky","PlaceName":"Berlin Tegel","RegionId":""},{"CityId":"BERL-sky","CountryId":"DE-sky","CountryName":"Germany","PlaceId":"SXF-sky","PlaceName":"Berlin Schoenefeld","RegionId":""},{"CityId":"BTVA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BTV-sky","PlaceName":"Burlington","RegionId":"VT"},{"CityId":"BLIA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BLI-sky","PlaceName":"Bellingham","RegionId":"WA"},{"CityId":"BRLA-sky","CountryId":"US-sky","CountryName":"United States","PlaceId":"BRL-sky","PlaceName":"Burlington","RegionId":"IA"}][0].CityId

我应该如何解析此 JSON 对象以访问各个键值对？

提前致谢，如有必要，我可以进一步详细说明问题！！

Answer 1

尝试将您的 JSON 路径表达式放入 expression syntax。在那里你可以使用完整的语法。像这样：

The first airport code is <? $TheResult.message.Places[0].CityId ?>

IBM Watson 对话：如何从上下文变量访问 JSON 对象？

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