How to get an Exception from another class c#

Question

i have these class

//Class 1, ViewModel
    public async System.Threading.Tasks.Task<JObject> ExecuteSystemObject(string parameters)
    {    
        ...
        dynamic j = await ExternalProject.ExecuteSomething<MyModel>(parameters);
        //How i can catch the error from the another class?
        ...
    }

//Class2, Manager
    public async Task<Object> ExecuteSomething<T>() where T : IModel, new()
    {
        ...
        WebResponse response = await ExternalProject.ExecuteRequestAsync(PostRequest);
        ...
    }

//Class 3, from a binding Project 
    public static async Task<WebResponse> ExecuteRequestAsync(WebRequest request)
    {
        try
        {
            return await request.GetResponseAsync();
        }
        catch(WebException e)
        {
            var resp = new StreamReader(e.Response.GetResponseStream()).ReadToEnd();
            dynamic obj = JsonConvert.DeserializeObject(resp);
            //I have the message error here
            var messageFromServer = obj.error.text;
            throw e;
        }
    }

I can get the error only in the last class, if i try to get the WebException in the other, it will return null for me. Then, how can i pass that error to the main class(1º one, ViewModel)?

Answer 1

Always use throw; whenever you want to rethrow an exception for you to be able to retain the stacktrace.

public async System.Threading.Tasks.Task<JObject> ExecuteSystemObject(string parameters)
{    
    try 
    {
        dynamic j = await ExternalProject.ExecuteSomething<MyModel>(parameters);
        //How i can catch the error from the another class?
        ...
    }
    catch(Exception e)
    {
        //WebException will be caught here
    }
}

public async Task<Object> ExecuteSomething<T>() where T : IModel, new()
{
    try 
    {
        WebResponse response = await ExternalProject.ExecuteRequestAsync(PostRequest);
    }
    catch(Exception)
    {
        throw;
    }

}

public static async Task<WebResponse> ExecuteRequestAsync(WebRequest request)
{
    try
    {
        //return await request.GetResponseAsync();
        throw new WebException("Test error message");
    }
    catch(WebException e)
    {
        throw;
    }
}

EDIT: Just a rule of thumb, only catch exceptions when you have something to do with it. If you are catching exceptions just to log it. Don't do it.