WebApi.Pagination

WebApi.Pagination allows you to easily add Range Header-based pagination to existing WebAPI endpoints that operate on IQueryable data sources.

NuGet package:

• WebApi.Pagination

Usage

Attributes

Simply add the [Pagination] attribute to a controller method with an IQueryable<T> return type.

Sample:

[Pagination]
public IQueryable<Person> Get()
{
  return Database.Persons.OrderBy(x => x.Name);
}

If you add any other filter attributes to your methods make sure the [Pagination] attribute is listed last. Otherwise modifications to the response made by other filters will be lost.

Use [Pagination(LongPolling = true)] to enable long polling.

Extension methods

If your controller method returns an HttpResponseMessage rather than a message content, you can use the .CreateResponsePagination() extension method for HttpRequestMessage to build a paginated response.

Sample:

[Pagination]
public HttpResponseMessage Get(HttpRequestMessage request)
{
  return request.CreateResponsePagination(
    Database.Persons.OrderBy(x => x.Name));
}

Use .CreateResponsePaginationAsync(..., longPolling: true) to enable long polling.

Sample project

The source code includes a sample project that uses demonstrates the usage of WebApi.Pagination. You can build and run it using Visual Studio 2015. By default the instance will be hosted by IIS Express at http://localhost:2085/attributes/ and http://localhost:2085/extension-methods/.

HTTP header samples

Subset

Request:

GET /resource
Range: elements=2-5

Response:

206 Partial Content
Content-Range: elements 2-3/5

[ 2, 3 ]

Tail

Request:

GET /resource
Range: elements=-2

Response:

206 Partial Content
Content-Range: elements 4-5/5

[ 4, 5 ]

Offset

Request:

GET /resource
Range: elements=2-

Response:

206 Partial Content
Content-Range: elements 2-5/5

[ 2, 3, 4, 5 ]

Long polling

Initial request:

GET /resource
Range: elements=0-

Response after timeout with no new content:

416 Requested Range not satisfiable

Client keeps polling automatically. Request:

GET /resource
Range: elements=0-

Response after delay until new content became available:

206 Partial Content
Content-Range: elements 0-1/*

[ 0, 1 ]

Client keeps polling automatically. Request:

GET /resource
Range: elements=2-

Response after delay until new content became available:

206 Partial Content
Content-Range: elements 2-3/4

[ 2, 3 ]

Client stops polling because content range with specified length (4 instead of *) indicates the end has been reached.