APIM context.Response.Body 始终为空

Question

我有一个 APIM 策略来向 Azure 事件中心发送请求和响应：

    <outbound>
        <log-to-eventhub logger-id="my-logger">@{
            var request = context.Request.Body.As<string>(preserveContent: true);
            var response = context.Response.Body?.As<string>(preserveContent: true);

            var json = new JObject(
                new JProperty("DateTimeStamp", DateTime.UtcNow),
                new JProperty("IpAddress",context.Request.IpAddress),
                new JProperty("RequestBody", request),
                new JProperty("ResponseBody", response),
                new JProperty("ResponseCode", context.Response.StatusCode)
            );
                
            return json.ToString();
        }</log-to-eventhub>
        <base />
    </outbound>

通过 Postman 或任何其他客户端发出的请求显示响应具有正确的正文，但在上面的代码中 context.Response.Body 始终为 null，因此进行了 null 检查。该消息在事件中心中显示正常，请求消息正确但响应为空。

API 上还有其他政策，但这是唯一的出站政策。可能是什么原因造成的？

使用完整的 Trace 消息进行编辑，删除空检查并按照建议使用 JObject。

log-to-eventhub (0.405 ms)
{
    "messages": [
        {
            "message": "Expression evaluation failed.",
            "expression": "\n            var request = context.Request.Body.As<string>(preserveContent: true);\n            var response = context.Response.Body.As<JObject>(preserveContent: true);\n\n            var json = new JObject(\n                new JProperty(\"DateTimeStamp\", DateTime.UtcNow),\n                new JProperty(\"ServiceName\",context.Deployment.ServiceName),\n                new JProperty(\"RequestId\",context.RequestId),\n                new JProperty(\"IpAddress\",context.Request.IpAddress),\n                new JProperty(\"OperationName\",context.Operation.Name),\n                new JProperty(\"RequestBody\", request),\n                new JProperty(\"ResponseBody\", response.ToString()),\n                new JProperty(\"ResponseCode\", context.Response.StatusCode)\n            );\n                \n            return json.ToString();\n        ",
            "details": "Object reference not set to an instance of an object."
        },
        "Expression evaluation failed. Object reference not set to an instance of an object.",
        "Object reference not set to an instance of an object."
    ]
}

Answer 1

代替 As<string> 尝试使用 As<JObject> 这将 return json JObject.

var response = context.Response.Body.As<JObject>(preserveContent: true);

JObject() Initializes a new instance of the JObject class.

查看更多信息https://www.newtonsoft.com/json/help/html/T_Newtonsoft_Json_Linq_JObject.htm

APIM context.Response.Body 始终为空

APIM context.Response.Body always null

azure-api-management

azure-eventhub