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## Angular Directive to Paginate Anything [![Build Status](https://travis-ci.org/begriffs/angular-paginate-anything.png?branch=master)](https://travis-ci.org/begriffs/angular-paginate-anything)

Add server-side pagination to any list or table on the page. This directive connects a variable of your choice on the local scope with data provied on a given URL. It provides a pagination user interface that triggers updates to the variable through paginated AJAX requests.

Pagination is a distinct concern and should be handled separately from other app logic. Do it right, do it in one place. Paginate anything!

DEMO

Usage

Include with bower

bower install angular-paginate-anything

The bower package contains files in the dist/directory with the following names:

  • angular-paginate-anything.js
  • angular-paginate-anything.min.js
  • angular-paginate-anything-tpls.js
  • angular-paginate-anything-tpls.min.js

Files with the min suffix are minified versions to be used in production. The files with -tpls in their name have the directive template bundled. If you don't need the default template use the angular-paginate-anything.min.js file and provide your own template with the templateUrl attribute.

Load the javascript and declare your Angular dependency

<script src="bower_components/angular-paginate-anything/dist/angular-paginate-anything-tpls.min.js"></script>
angular.module('myModule', ['bgf.paginateAnything']);

Then in your view

<!-- elements such as an ng-table reading from someVariable -->

<bgf-pagination
  collection="someVariable"
  url="'http://api.server.com/stuff'">
</bgf-pagination>

The pagination directive uses an external template stored in tpl/paginate-anything.html. Host it in a place accessible to your page and set the templateUrl attribute. Note that the url param can be a scope variable as well as a hard-coded string.

Benefits

  • Attaches to anything — ng-repeat, ng-grid, ngTable etc
  • Server side pagination scales to large data
  • Works with any MIME type through RFC2616 Range headers
  • Handles finite or infinite lists
  • Negotiates per-page limits with server
  • Keeps items in view when changing page size
  • Twitter Bootstrap compatible markup

Directive Attributes

Name Description Access
url url of endpoint which returns a JSON array Read/write. Changing it will reset to the first page.
url-params map of strings or objects which will be turned to ?key1=value1&key2=value2 after the url Read/write. Changing it will reset to the first page.
headers additional headers to send during request Write-only.
page the currently active page Read/write. Writing changes pages. Zero-based.
per-page (default=`50`) Max number of elements per page Read/write. The server may choose to send fewer items though.
per-page-presets Array of suggestions for per-page. Adjusts depending on server limits Read/write.
auto-presets (default=`true`) Overrides per-page presets and client-limit to quantized values 1,2,5,10,25,50... Read/write.
client-limit (default=`250`) Biggest page size the directive will show. Server response may be smaller. Read/write.
link-group-size (default=`3`) Number of elements surrounding current page. illustration Read/write.
num-items Total items reported by server for the collection Read-only.
num-pages num-items / per-page Read-only.
server-limit Maximum results the server will send (Infinity if not yet detected) Read-only.
range-from Position of first item in currently loaded range Read-only.
range-to Position of last item in currently loaded range Read-only.
reload-page If set to true, the current page is reloaded. Write-only.
size Twitter bootstrap sizing `sm`, `md` (default), or `lg` for the navigation elements. Write-only.
passive If using more than one pagination control set this to 'true' on all but the first. Write-only.
transform-response Function that will get called once the http response has returned. See Angular's $https documentation for more information. Read/write. Changing it will reset to the first page.
method Type of request method. Can be either GET or POST. Default is GET. Read/write.
post-data An array of data to be sent when method is set to POST. Read/write.
load-fn A callback function to perform the request. Gets the http config as parameter and must return a promise. Write-only.

Events

The directive emits events as pages begin loading (pagination:loadStart) or finish (pagination:loadPage) or errors occur (pagination:error). To catch these events do the following:

$scope.$on('pagination:loadPage', function (event, status, config) {
  // config contains parameters of the page request
  console.log(config.url);
  // status is the HTTP status of the result
  console.log(status);
});

The pagination:loadStart is passed the client request rather than the server response.

To trigger a reload the pagination:reload event can be send:

function () {
  $scope.$broadcast('pagination:reload');
}

How to deal with sorting, filtering and facets?

Your server is responsible for interpreting URLs to provide these features. You can connect the url attribute of this directive to a scope variable and adjust the variable with query params and whatever else your server recognizes. Or you can use the url-params attribute to connect a map of strings or objects which will be turned to ?key1=value1&key2=value2 after the url. Changing the url or url-params causes the pagination to reset to the first page and maintain page size.

Example:

$scope.url = 'api/resources';
$scope.urlParams = {
  key1: "value1",
  key2: "value2"
};

Will turn into the URL of the resource that is being requested: api/resources?key1=value1&key2=value2

What your server needs to do

This directive decorates AJAX requests to your server with some simple, standard headers. You read these headers to determine the limit and offset of the requested data. Your need to set response headers to indicate the range returned and the total number of items in the collection.

You can write the logic yourself, or use one of the following server side libraries.

Framework Solution
Ruby on Rails begriffs/clean_pagination gem
Node.js node-paginate-anything module
Express JS from scratch howto
ServiceStack for .NET Service Stack .NET howto
ASP.NET Web API ASP.NET Web API howto

For a reference of a properly configured server, visit pagination.begriffs.com.

Here is an example HTTP transaction that requests the first twenty-five items and a response that provides them and says there are one hundred total items.

Request

GET /stuff HTTP/1.1
Range-Unit: items
Range: 0-24

Response

HTTP/1.1 206 Partial Content
Content-Range: 0-24/100
Range-Unit: items
Content-Type: application/json

[ etc, etc, ... ]

In short your server parses the Range header to find the zero-based start and end item. It includes a Content-Range header in the response disclosing the unit and range it chooses to return, along with the total items after a slash, where total items can be "*" meaning unknown or infinite.

When there are zero elements to return your server should send status code 204 (no content), Content-Range: */0, and an empty body (or [] if the endpoint normally returns a JSON array).

To do all this header stuff you'll need to enable CORS on your server. In a Rails app you can do this by adding the following to config/application.rb:

config.middleware.use Rack::Cors do
  allow do
    origins '*'
    resource '*',
      :headers => :any,
      :methods => [:get, :options],
      :expose => ['Content-Range', 'Accept-Ranges']
  end
end

For a more complete implementation including other appropriate responses see my clean_pagination gem.

Using the load-fn callback

Instead of having paginate-anything handle the http requests there is the option of using a callback function to perform the requests. This might be helpful e.g. if the data does not come from http endpoints, further processing of the request needs to be done prior to submitting the request or further processing of the response is necessary.

The callback can be used as follows:

<bgf-pagination collection="data" page="filter.page" per-page="filter.perpage" load-fn="callback(config)"></bgf-pagination>
$scope.callback = function (config) {
  return $http(config);
}

// alternatively
$scope.callback = function(config) {
  return $q(function(resolve) {
    resolve({
      data: ['a', 'b'],
      status: 200,
      config: {},
      headers: function(headerName) {
        // fake Content-Range headers
        return '0-1/*';
      }
    });
  });
}

Further reading

Thanks

Thanks to Steve Klabnik for discussions about doing hypermedia/HATEOAS right, and to Rebecca Wright for reviewing and improving my original user interface ideas for the paginator.