Microsoft.Azure.WebJobs.Script：无法将“System.String”类型的对象转换为“Microsoft.AspNetCore.Http.HttpRequest”类型。回来的时候答案

【问题标题】：Microsoft.Azure.WebJobs.Script: Unable to cast object of type 'System.String' to type 'Microsoft.AspNetCore.Http.HttpRequest'. when returnMicrosoft.Azure.WebJobs.Script：无法将“System.String”类型的对象转换为“Microsoft.AspNetCore.Http.HttpRequest”类型。回来的时候
【发布时间】：2020-12-22 17:52:11
【问题描述】：

我有一个用 JS 编写的 Azure 函数，它由服务总线触发并生成文件到 Blob 存储。当我尝试返回 HTTP 结果时，我收到如下错误：

System.Private.CoreLib: Exception while executing function: Functions.categoryMessageConsumer. Microsoft.Azure.WebJobs.Script: Unable to cast object of type 'System.String' to type 'Microsoft.AspNetCore.Http.HttpRequest'.

我不知道为什么结果试图映射到 HttpRequest 对象。

index.ts:

import { AzureFunction, Context, HttpRequest } from '@azure/functions';
...

const serviceBusTopicTrigger: AzureFunction = async function(context: Context, req: HttpRequest) {
    let categoryMessage: CategoryMessage = Object.assign(new CategoryMessage(), req);
    let messageValidationResult = await categoryMessage.validate();
    if(!messageValidationResult.isValid) {
        context.log.error(messageValidationResult.errors);
        return {
            status: 400,
            body: "Unexpected error"
        };
    }

    ...
}

function.json 输出绑定：

...
    {
      "type": "http",
      "direction": "out",
      "name": "$return"
    }
...

host.json

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "extensionBundle": {
    "id": "Microsoft.Azure.Functions.ExtensionBundle",
    "version": "[1.*, 2.0.0)"
  }
}

【问题讨论】：

标签： javascript typescript azure azure-blob-storage

【解决方案1】：

var http = require('https');
module.exports = function (context, eventHubMessages) {
    context.log(`JavaScript eventhub trigger function called for message array ${eventHubMessages}`);
    
    eventHubMessages.forEach((message, index) => {
        
        function callService(msg) {
            let promise = new Promise((resolve, reject) => {
                var options = {
                    host: process.env["HOST"],
                    port: process.env["PORT"],
                    path: process.env["PATH"],
                    method: process.env["WEBSERVICE_METHOD"],
                    headers: {
                        'Content-Type': process.env["WEBSERVICE_CONTENT_TYPE"],
                        'x-api-key' : process.env["WEBSERVICE_API_KEY"]
                    }
                };
                var response = '';
                const request = http.request(options, (res) => {
                    res.on('data', (d) => {
                        response += d;
                    })
    
                    res.on('end', (d) => {
                        context.res = {
                            body: response
                        };
                        resolve(response);
                    })
                });

                request.on('error', (error) => {
                    context.log.error(error);
                    reject(error);
                    context.done();
                })
                
                request.write(msg);
                request.end();

              });
              promise.then((response) => {
                context.log(`mensagge send: ${msg}`);
                context.log(`response: ${response}`);
                context.done();
            });
            
        }
        
        callService(message);
    });
};

这是我的 index.js

现在是我的 function.js：

{
  "bindings": [
    {
      "type": "eventHubTrigger",
      "name": "eventHubMessages",
      "direction": "in",
      "eventHubName": "event-hub-name",
      "connection": "CONNECTION_EVENT_HUB",
      "cardinality": "many",
      "consumerGroup": "$Default",
      "dataType": "string"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "$return"
    }
  ]
}

在 local.settings.json 中，我声明了所有环境变量，如 HOST、PORT、CONNECTION_EVENT_HUB 等。

【讨论】：

【解决方案2】：

这是因为，您的函数可能正在尝试创建另一个它没有预料到的对象。

正如您提到的响应变量名称为$return 并且它是预期的。而不是这样，编码你的函数如下：

function.json:

{
    "disabled": false,    
    "bindings": [
        {
            "authLevel": "function",
            "type": "httpTrigger",
            "direction": "in",
            "name": "req"
        },
        {
            "type": "http",
            "direction": "out",
            "name": "res"
        }
    ]
}

JS 代码：

module.exports = function(context, req) {
    context.log('Node.js HTTP trigger function processed a request. RequestUri=%s', req.originalUrl);

    if (req.query.name || (req.body && req.body.name)) {
        context.res = {
            // status defaults to 200 */
            body: "Hello " + (req.query.name || req.body.name)
        };
    }
    else {
        context.res = {
            status: 400,
            body: "Please pass a name on the query string or in the request body"
        };
    }
    context.done();
};

function.json中的配置选项，您可以访问here和here。

【讨论】：