使用ServiceStack处理错误消息

Question

Is there a recommended way to keep error messages within the requested objects from a webservice?

In some examples I see the webservices returning a wrapper class containing some HTTP error codes, others hold messages of .NET-exceptions. On the other hand there are the examples returning the plain objects or list of objects.

Answer 1

The error handling can appear confusing at first. The official documentation is here . But essentially ServiceStack tries to return errors in a consistent way so your client always knows how to handle them. You should throw exceptions in the normal c# way, ServiceStack will catch these and encapsulated it in a ResponseStatus object, which looks like this:

public class ResponseStatus 
{
    public string ErrorCode { get; set; }
    public string Message { get; set; }
    public string StackTrace { get; set; }
    public List<ResponseError> Errors { get; set; }
}

Full definition here

So you will receive a response object that contains a property called ResponseStatus having the populated ResponseStatus object above.

Things to note:

• The StackTrace property will only be included if you enable debug mode in your ServiceStack AppHost Config. ie:

   SetConfig(new HostConfig { DebugMode = true }); 

  This will be the .NET exception you are referring to, and is shown conditionally depending if DebugMode is set.

  ---

• The Errors list of ResponseError is only populated for validation error failures. This will be the list of validation errors. Which is why you see in some examples a plain error response (ie not a validation error) , and a response with a list of errors attached (validation error) . You should also read the section about validation in the documentation . The format of ResponseError object is this:

   public class ResponseError { public string ErrorCode { get; set; } public string FieldName { get; set; } public string Message { get; set; } } 

  The ErrorCode and Message of the ResponseStatus object will be taken from the first item of the Errors list.

Where things get confusing for some people is how, to include the ResponseStatus as a property of your expected response request.

So assuming your wanted to return a Person object such as this:

class Person
{
    string FirstName { get; set; }
    string LastName { get; set; }
}

If a validation exception was thrown for a request that returns this Person response you may get a JSON response like this:

{
    "ResponseStatus": {
         "ErrorCode": "ShouldNotBeEmpty",
         "Message": "'FirstName' should not be empty",
         "StackTrace": "..."
         "Errors": [
             {
                 "ErrorCode": "ShouldNotBeEmpty",
                 "FieldName": "FirstName",
                 "Message": "'FirstName' should not be empty"
             },
             {
                 "ErrorCode": "ShouldNotBeEmpty",
                 "FieldName": "LastName",
                 "Message": "'LastName' should not be empty"
             },
         ]
    }
}

Note that the response object of Person is not included in this response, just an object containing the ResponseStatus property. If we want to include the response object with the status we must declare our person class this way:

class PersonResponse
{
    ResponseStatus ResponseStatus { get; set; }
    string FirstName { get; set; }
    string LastName { get; set; }
}

Then when an exception is thrown the response will include the response object and it's status:

{
    "FirstName": "",
    "LastName": "",
    "ResponseStatus": {
        ...

ServiceStack provides you with a lot of control over the error format you return when an exception is thrown, it's best you read through the official documentation I linked to above to understand it. Customisation is more of an advanced topic.