c# - 测试 Alexa 技能返回 "Error converting the Lambda event JSON payload to a string"

Question

我正在尝试让 Alexa 设备说出我从用 C# 编写的 Lambda 函数返回的一串文本。

现在我已经编写了一个返回字符串的基本方法。

[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.Json.JsonSerializer))]

namespace AlexaTeachMeNewWord
{
    public class Function
    {
        public string FunctionHandler(object input, ILambdaContext context)
        {
            return "Hello this is a test";
        }
    }
}

使用适用于 Visual Studio 2019 的 AWS 工具，如果我使用示例 Alexa 调用测试该函数，则会清楚地返回文本字符串。

但是，当我将函数发布到 AWS Lambda 后，我收到以下错误消息，告诉我将 Lambda 事件 JSON 负载转换为字符串时出错

{
  "errorType": "JsonSerializerException",
  "errorMessage": "Error converting the Lambda event JSON payload to a string. JSON strings must be quoted, for example \"Hello World\" in order to be converted to a string: Unexpected character encountered while parsing value: {. Path '', line 1, position 1.",
  "stackTrace": [
    "at Amazon.Lambda.Serialization.Json.JsonSerializer.Deserialize[T](Stream requestStream)",
    "at lambda_method(Closure , Stream , Stream , LambdaContextInternal )"
  ],
  "cause": {
    "errorType": "JsonReaderException",
    "errorMessage": "Unexpected character encountered while parsing value: {. Path '', line 1, position 1.",
    "stackTrace": [
      "at Newtonsoft.Json.JsonTextReader.ReadStringValue(ReadType readType)",
      "at Newtonsoft.Json.JsonTextReader.ReadAsString()",
      "at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType(JsonReader reader, JsonContract contract, Boolean hasConverter)",
      "at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)",
      "at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)",
      "at Newtonsoft.Json.JsonSerializer.Deserialize[T](JsonReader reader)",
      "at Amazon.Lambda.Serialization.Json.JsonSerializer.Deserialize[T](Stream requestStream)"
    ]
  }
}

这很令人困惑，因为我没有尝试返回 JSON 有效负载。

Answer 1

经过进一步调查，我发现 Alexa 不会简单地说出返回的字符串，您必须构建一个响应对象并将其返回。

使用 Alexa.NET，我编写了以下类，它允许我指示 Alexa 设备说出我的文本字符串。

希望这对某人有帮助。

public class Function
{
    public SkillResponse FunctionHandler(SkillRequest req, ILambdaContext context)
    {
        // create the speech response
        var speech = new SsmlOutputSpeech();
        speech.Ssml = "<speak>This is an test.</speak>";

        // create the response
        var responseBody = new ResponseBody();
        responseBody.OutputSpeech = speech;
        responseBody.ShouldEndSession = true; // this triggers the reprompt
        responseBody.Card = new SimpleCard { Title = "Test", Content = "Testing Alexa" };

        var skillResponse = new SkillResponse();
        skillResponse.Response = responseBody;
        skillResponse.Version = "1.0";

        return skillResponse;
    }
}