catch 后继续 try 块。在一次尝试中记录所有异常

Question

我想做 4 个动作，每个动作都可以抛出一个异常。我需要全部执行并记录沿途发生的所有错误

我可以大而笨拙地做到这一点：

var exceptions = new List<ExceptionType1>();
try {
    result1 = await action1();
} catch (ExceptionType1 ex1) {
    exceptions.Add(ex1);
    logger.Log(ex1);
}

try {
    result2 = await action2();
} catch (ExceptionType1 ex1) {
    exceptions.Add(ex1);
    logger.Log(ex1);
}

try {
    result3 = await action3(result1);
} catch (ExceptionType2 ex2) {
    var ex1 = new ExceptionType1(ex2);
    exceptions.Add(ex1);
    logger.Log(ex1);
}

try {
    result4 = await action4(result2);
} catch (ExceptionType2 ex2) {    
    var ex1 = new ExceptionType1(ex2);
    exceptions.Add(ex1);    
    logger.Log(ex1);
}

if (exceptions.Count > 0) {
    return false;
}

显然，有时像这样的东西会迅速膨胀 我想以更优雅的方式做到这一点：

var exceptions = new List<ExceptionType1>();
try {
    result1 = await action1();
    result2 = await action2();
    result3 = await action3(result1);
    result4 = await action4(result2);
} catch(Exception ex) {
    var ex1 = new ExceptionType1(ex);
    exceptions.Add(ex1);
    logger.Log(ex1);
    ???
    ~~Goto try block and continue executing~~
    ???

}

if (exceptions.Count > 0) {
    return false;
}    

我试图找到有关如何返回 try 块并继续执行的信息，但未成功。可能吗。有没有其他我没有考虑过的解决方法？

Answer 1

我猜的一种方法（考虑到你的重新装备）是创建一个本地方法

var exceptions = new List<Exception>();

async Task<T> DoAsync<T>(Func<Task<T>> func)
{
   try
   {
      return await func();
   }
   catch (Exception ex)
   {
      exceptions.Add(ex);
      logger.Log(ex);
   }

   return default;
}

result1 = await DoAsync(action1);
result2 = await DoAsync(action2);

if (exceptions.Count > 0)
{
   return false;
}

Answer 2

也许您可以将其提取到local function：

// declare this inside the method that contains the code you showed
async void GetResult<TResult, TException>(out TResult result, Func<Task<TResul>> resultGetter, Func<TException, ExceptionType1> mapper)
    where TException: Exception {
    try {
        result = await resultGetter();
    } catch (TException ex) {
        var ex1 = mapper(ex)
        exceptions.Add(ex1);
        logger.Log(ex1);
    }
}

来电者：

GetResult(out result1, action1, (ExceptionType1 e) => e);
GetResult(out result2, action2, (ExceptionType1 e) => e);
GetResult(out result3, async () => await action3(result1), (ExceptionType2 e) => new ExceptionType1(e));
GetResult(out result4, async () => await action4(result2), (ExceptionType2 e) => new ExceptionType1(e));

Answer 3

如何回到 try 块并继续执行.. 有可能吗？

你不能做你正在寻找的东西：https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/try-catch

块一直执行，直到抛出异常或成功完成。

一旦出块，连已经初始化的变量也会回滚。

停止执行受安全保护的代码是异常的全部意义。

按照其他两个答案的建议来简化您的代码

Answer 4

我认为 Task 的 WhenAll() 方法将适合您的目的： https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/try-catch#taskwhenall-example 首先，您的操作已经是异步的。此外，如果您需要遵循任何执行顺序，您可以划分为多个 WhenAll() 块

来自文档的示例：

public async Task action1()
{
    throw new InvalidOperationException();
}
public async Task action2()
{
    throw new NotImplementedException();
}

public async Task action3()
{
    throw new InvalidCastException();
}
public async Task DoMultipleAsync()
{
    Task theTask1 = action1();
    Task theTask2 = action2();
    Task theTask3 = action3();

    Task allTasks = Task.WhenAll(theTask1, theTask2, theTask3);

    try
    {
        await allTasks;
    }
    catch (Exception ex)
    {
        Console.WriteLine("Exception: " + ex.Message);
        Console.WriteLine("Task IsFaulted: " + allTasks.IsFaulted);
        foreach (var inEx in allTasks.Exception.InnerExceptions)
        {
            Console.WriteLine("Task Inner Exception: " + inEx.Message);
        }
    }
}

// Output:
// Exception: Operation is not valid due to the current state of the object.
// Task IsFaulted: True
// Task Inner Exception: Operation is not valid due to the current state of the object.
// Task Inner Exception: The method or operation is not implemented.
// Task Inner Exception: Specified cast is not valid.