“异步"Azure Function App 未按预期等待

#39;async#39; Azure Function App not awaiting as expected(“异步Azure Function App 未按预期等待)

问题描述

我正在尝试使用 Azure storage SDK for node 在表格存储中创建一个表格，如果它不存在的话.

I'm attempting to use the Azure storage SDK for node to create a Table in Table Store, if it does not exist.

以下代码有效，返回200响应，虽然没有响应内容.但是，该表已按预期创建.

The following code is valid and returns a 200 response, although there is no response content. However, the table is created as expected.

经过调查，我可以看到 Azure Function 应用程序正在记录以下内容 -

Upon investigation, I can see that the Azure Function app is logging the following -

创建表测试".
[警告] 警告:函数执行完成后对上下文对象的日志"意外调用.请检查未等待的异步调用或在函数执行完成之前对完成"的调用.

Creating table 'Test'.
[warn] Warning: Unexpected call to 'log' on the context object after function execution has completed. Please check for asynchronous calls that are not awaited or calls to 'done' made before function execution completes.

看来，虽然 createTableInTableStore 按预期工作，但我的函数的 async/await 部分却没有.我怀疑我做错了什么，但从外观上看，我正确地实现了 await 以及何时需要它.

So it seems that while the createTableInTableStore is working as expected, the async/await part of my function is not. I suspect that I'm doing something wrong, but from the looks of it I am correctly implementing await as and when it's requried.

如何让函数等待 createTableInTableStore 方法完成后再继续?

How can I get the function to wait for the createTableInTableStore method to complete before it move on?

请注意，需要 azure-storage npm 包(npm install azure-storage).

Please note that the azure-storage npm package is required (npm install azure-storage).

module.exports = async function (context) {
    var azure_storage = require('azure-storage');
    var table_service = azure_storage.createTableService(process.env["AzureWebJobsStorage"]);
    var create_table_result = await createTableInTableStore(context, table_service, "Test");
    return {
        res: create_table_result
    };
};

async function createTableInTableStore(context, table_service, table_name) {
    context.log("Creating table '"+table_name+"'.");
    return await table_service.createTableIfNotExists(table_name, function(error, result, response) {
        if (!error && result) {
            context.log.info("[Info] Table created successfully.")
        } else if (!error && !result) {
            context.log.info("[Info] Table already exists.")
        }
        if (error) {
            context.log.error("[Error] An unexpected error occurred.")
            context.log.error(" -----> " + response)
        }
    });
}

推荐答案

你可以返回一个它会起作用的承诺.并在使用 await 时使用 try catch 处理错误.

you can return a promise it will work. and use try catch to handle errors when you use await.

module.exports = async function (context) {
    try{
    var azure_storage = require('azure-storage');
    var table_service = azure_storage.createTableService(process.env["AzureWebJobsStorage"]);
    var create_table_result = await createTableInTableStore(context, table_service, "Test");
      return {
          res: create_table_result
      };
    }catch(err){
    //handle errr
    console.log(err);
     }
};

function createTableInTableStore(context, table_service, table_name) {
    context.log("Creating table '"+table_name+"'.");
    return new Promise((resolve, reject) => {
      table_service.createTableIfNotExists(table_name, function(error, result, response) {
        if (!error && result) {
            context.log.info("[Info] Table created successfully.")
            resolve(result)
        } else if (!error && !result) {
            context.log.info("[Info] Table already exists.")
            resolve(response)
        }
        if (error) {
            context.log.error("[Error] An unexpected error occurred.")
            context.log.error(" -----> " + response)
            reject(error)
        }
    });
});
}

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