Request & Response filters

ServiceStack's Global Request and Response filter lets you apply your own generic custom behavior to ServiceStack Requests. These should be registered in your AppHost.Configure() Startup:

Global Request Filters​

The Request Filters are applied before the service gets called and accepts: (IRequest, IResponse, RequestDto) e.g:

//Global Request Filter to check if the user has a session initialized
this.GlobalRequestFilters.Add((req, res, requestDto) => 
{
    var sessionId = req.GetCookieValue("user-session");
    if (sessionId == null)
    {
        res.ReturnAuthRequired();
    }
});

Async​

Use GlobalRequestFiltersAsync when you need to make async requests in your Global Request Filters, e.g:

Simplified example of ServiceStack's Validation Feature:

//Global Async Request Filter to automatically validate a Request DTO
this.GlobalRequestFiltersAsync.Add(async (req, res, requestDto) => 
{    
    var validator = ValidatorCache.GetValidator(req, requestDto.GetType());
    if (validator == null)
        return;

    var validationResult = await Validate(validator, req, requestDto);
    if (validationResult.IsValid)
        return;

    var errorResponse = DtoUtils.CreateErrorResponse(requestDto, validationResult.ToErrorResult());
    
    await res.WriteToResponse(req, errorResponse);
});

Simple Rate-limiting example:

GlobalRequestFiltersAsync.Add(async (req,res,dto) => {
    var response = await client.Send(new CheckRateLimit { 
        Service = dto.GetType().Name,
        IpAddress = req.UserHostAddress,
     });
     if (response.RateLimitExceeded) 
     {
         res.StatusCode = 403;
         res.StatusDescription = "RateLimitExceeded";
         res.EndRequest();
     }
})

Global Response Filters​

The Response Filters are applied after your service is called and accepts: (IRequest, IResponse, ResponseDto) e.g:

//Add a response filter to add a 'Content-Disposition' header so browsers treat it as a native .csv file
this.GlobalResponseFilters.Add((req, res, responseDto) => 
{
    if (req.ResponseContentType == ContentType.Csv)
    {
        res.AddHeader(HttpHeaders.ContentDisposition,
        string.Format("attachment;filename={0}.csv", req.OperationName));
    }
});

Global Request and Response Filters​

• PreRequestFilters - Global Filter executed at the start of all ServiceStack Requests
• GlobalRequestFilters - Global Request Filter for ServiceStack Service Requests
• GlobalResponseFilters - Global Response Filter for ServiceStack Service Requests
• GatewayRequestFilters - Request Filter for Service Gateway Requests
• GatewayResponseFilters - Response Filter for Service Gateway Requests
• GlobalMessageRequestFilters - Request Filter for Service MQ Requests
• GlobalMessageResponseFilters - Response Filter for Service MQ Requests

Async versions are also available:

• GlobalRequestFiltersAsync - Global Request Filter for ServiceStack Service Requests
• GlobalResponseFiltersAsync - Global Response Filter for ServiceStack Service Requests
• GatewayRequestFiltersAsync - Request Filter for Service Gateway Requests
• GatewayResponseFiltersAsync - Response Filter for Service Gateway Requests
• GlobalMessageRequestFiltersAsync - Request Filter for Service MQ Requests
• GlobalMessageResponseFiltersAsync - Response Filter for Service MQ Requests

Typed Request Filters​

A more typed API to register Global Request and Response filters per Request DTO Type are available under the RegisterTyped* API's in AppHost where you can register both typed Request and Response Filters for HTTP and MQ Services independently:

void RegisterTypedRequestFilter<T>(Action<IRequest, IResponse, T> filterFn);
void RegisterTypedResponseFilter<T>(Action<IRequest, IResponse, T> filterFn);
void RegisterTypedMessageRequestFilter<T>(Action<IRequest, IResponse, T> filterFn);
void RegisterTypedMessageResponseFilter<T>(Action<IRequest, IResponse, T> filterFn);

Here's an example usage that enables more flexibility in multi-tenant solutions by attaching custom data on incoming requests, e.g:

public override void Configure(Container container)
{
    RegisterTypedRequestFilter<Resource>((req, res, dto) =>
    {
        var route = req.GetRoute();
        if (route != null && route.Path == "/tenant/{TenantName}/resource")
        {
            dto.SubResourceName = "CustomResource";
        }
    });
}

Autowired Typed Request Filters​

You can also register Autowired Typed Request and Response Filters which lets you handle Request DTOs in a Typed Filter similar to how Autowired Services handles Typed Request DTOs with access to IOC injected dependencies.

Autowired Typed Filters just needs to implement ITypedFilter<TRequest> and can be registered in the IOC like a regular dependency, e.g:

container.RegisterAutoWiredAs<Dependency, IDependency>();
container.RegisterAutoWired<TypedRequestFilter>();

Then can be registered using the new RegisterTypedRequestFilter overload:

this.RegisterTypedRequestFilter(c => c.Resolve<TypedRequestFilter>());

Which invokes the Typed Request Filter on each MyRequest where it's able to access any IOC injected dependencies, e.g:

class TypedRequestFilter : ITypedFilter<MyRequest>
{
    public IDependency Dependency { get; set; } // injected by IOC
 
    public void Invoke(IRequest req, IResponse res, MyRequest dto) 
    {
        // Handle MyRequest using a Request Filter
        if (!Dependency.GrantAccess(dto, req))
        {
            res.StatusCode = (int)HttpStatusCode.Forbidden;
            res.StatusDescription = "Thou shall not pass";
            res.EndRequest();
        }
    }
}

Apply custom behavior to multiple DTO's with Interfaces​

Typed Filters can also be used to apply custom behavior on Request DTO's sharing a common interface, e.g:

public override void Configure(Container container)
{
    RegisterTypedRequestFilter<IHasSharedProperty>((req, res, dtoInterface) => {
        dtoInterface.SharedProperty = "Is Shared";    
    });
}

Message Queue Endpoints​

Non-HTTP requests like Redis MQ are treated as Internal Requests which only execute the alternate GlobalMessageRequestFilters and GlobalMessageResponseFilters and Action Filter attributes.