backbone-pageable

A pageable, drop-in replacement for Backbone.Collection inspired by Backbone.Paginator, but much better.

Table of Contents

Advantages

Supports client-side and server-side operations: You can initialize Backbone.PageableCollection to paginate and/or sort on the client-side, server-side or both.
Infinite paging: Many public APIs like Github or Facebook support infinite paging, Backbone.PageableCollection can handle them easily.
Comes with reasonable defaults: Server API parameters preconfigured to work with most Rails RESTful APIs by default.
Works well with existing server-side APIs: Query parameter mappings are all configurable, and you can use either 0-based or 1-based indices.
Bi-directional event handling: In client-mode, any changes done on one page is immediately reflected on the others with the appropriate events propagated.
100% compatible with existing code: Backbone.PageableCollection is a strict superset of Backbone.Collection and passes its test suite.
Well tested: Comes with 100s of tests in addition to the Backbone.Collection test suite.
Well documented: Use cases and functionality are thoroughly documented.
No surprising behavior: Backbone.PageableCollection performs internal state sanity checks at appropriate times, so it is next to impossible to get into a weird state.
Light-weight: The library is only 4 kb minified and gzipped.

Playable Demos

The following examples utilizes Backgrid.js to render the collections.

Installation

Installing from Node.js

npm install backbone-pageable

Installing from Bower

bower install backbone-pageable

Browser

<script src="underscore.js"></script>
<script src="backbone.js"></script>
<script src="backbone-pageable.js"></script>

Getting to the Backbone.PageableCollection Class from Node.js and AMD

var PageableCollection = require("backbone-pageable");

Getting to the Backbone.PageableCollection Class in the Browser

var PageableCollection = Backbone.PageableCollection;

Introduction

Like Backbone.Collection, you can provide a URL endpoint, configure your initial pagination state and server API mapping by extending Backbone.PageableCollection:

var Book = Backbone.Model.extend({});

var Books = Backbone.PageableCollection.extend({
  model: Book,
  url: "api.mybookstore.com/books",

  // Any `state` or `queryParam` you override in a subclass will be merged with
  // the defaults in `Backbone.PageableCollection` 's prototype.
  state: {

    // You can use 0-based or 1-based indices, the default is 1-based.
    // You can set to 0-based by setting ``firstPage`` to 0.
    firstPage: 0,

    // Set this to the initial page index if different from `firstPage`. Can
    // also be 0-based or 1-based.
    currentPage: 2,

    // Required under server-mode
    totalRecords: 200
  },

  // You can configure the mapping from a `Backbone.PageableCollection#state`
  // key to the query string parameters accepted by your server API.
  queryParams: {

    // `Backbone.PageableCollection#queryParams` converts to ruby's
    // will_paginate keys by default.
    currentPage: "current_page",
    pageSize: "page_size"
  }
});

You can initialize state and queryParams from the constructor too:

var Books = Backbone.PageableCollection.extend({
  model: Book,
  url:"api.mybookstore.com/books"
});

var books = new Books([], {

  // All the `state` and `queryParams` key value pairs are merged with
  // the defaults too.
  state: {
    firstPage: 0,
    currentPage: 0
  },

  queryParams: {
    currentPage: "current_page",
    pageSize: "page_size"
  }
});

Adapting to a Server API

To adapt to an existing server API that do not use will_paginate keys, you can configure the queryParams object hash to map state keys to the query parameters your server will accept. Those query parameters will be in the query string of the URL used for fetching. You can also put extra items into queryParams and they will be in the query string as is. Setting null as the value of any mapping will remove it from the query string. Finally, the values in the queryParams can be either a literal value or a parameter-less function that returns a value.

This is a listing of the default state and queryParam values.

`state`	`queryParams`
Attribute Value	Attribute Value
============ ===== firstPage 1 lastPage null	============= ============================
currentPage null	currentPage "page"
pageSize 25	pageSize "per_page"
totalPages null	totalPages "total_pages"
totalRecords null	totalRecords "total_entries"
sortKey null	sortKey "sort_by"
order -1	order "order"
	directions { "-1": "asc", "1": "desc" }

You can consult the API documentation for a detailed explaination of these fields.

Fetching Data and Managing States

You can access the pageable collection's internal state by looking at the state object attached to it. This state object, however, is generally read-only after initialization. There are various methods to help you manage this state, you should use them instead of manually modifying it. For the unusual circumstances where you need to modify the state object directly, a sanity check will be performed at the next time you perform any pagination-specific operations to ensure internal state consistency.

Method	Use When
`setPageSize`	Changing the page size
`setSorting`	Changing the sorting
`switchMode`	Switching between modes
`state`	Need to read the internal state
`get*Page`	Need to go to a different page
`hasPrevious, hasNext`	Check if paging backward or forward is possible

In addition to the above methods, you can also synchronize the state with the server during a fetch. Backbone.PageableCollection overrides the default Backbone.Collection#parse method to support an additional response data structure that contains an object hash of pagination state. The following is a table of the response data structure formats Backbone.PageableCollection accepts.

Without State	With State
[{}, {}, ...]	[{ pagination state }, [{}, {} ...]]

Bootstrapping

Backbone.PageableCollection is 100% compatible with Backbone.Collection 's interface, so you can bootstrap the models and supply a comparator to the constructor just like you are used to:

// Bootstrap with just 1 page of data for server-mode, or all the pages for
// client-mode.
var books = new Books([
  { name: "A Tale of Two Cities" },
  { name: "Lord of the Rings" },
  // ...
], {
  // Paginate and sort on the client side, default is `server`.
  mode: "client",
  // This will maintain the current page in the order the comparator defined
  // on the client-side, regardless of modes.
  comparator: function (model) { return model.get("name"); }
});

Pagination

Server-Mode

Backbone.Pagination defaults to server-mode, which means it only holds one page of data at a time. All of the get*page operations are done by delegating to fetch. They return a jqXHR in this mode.

books.getFirstPage();
books.getPreviousPage();
books.getNextPage();
books.getLastPage();

// All the `get*Page` methods under server-mode delegates to `fetch`, so you
// can attach a callback to the returned `jqXHR` objects' `done` event.
books.getPage(2).done(function () {
  // do something ...
});

All of the get*Page methods accept the same options Backbone.Collection#fetch accepts under server-mode.

Client-Mode

Client-mode is a very convenient mode for paginating a handful of pages entirely on the client side without going through the network page-by-page. This mode is best suited if you only have a small number of pages so sending all of the data to the client is not too time-consuming.

var book = new Book([
  // Bootstrap all the records for all the pages here
], { mode: "client" });

All of the get*Page methods reset the pageable collection's data to the models belonging to the current page and return the collection itself instead of a jqXHR.

// You can immediately operate on the collection without waiting for jQuery to
// call your `done` callback.
var json = JSON.stringify(books.getLastPage());

// You can force a fetch in client-mode to get the most updated data if the
// collection has gone stale.
books.getFirstPage({ fetch: true });

// Do something interesting with books...

Infinite-Mode

Infinite paging mode is a hybrid of server mode and client mode. Once initialized and bootstrapped, paging backwards will be done on the client-side by default while paging forward will be done by fetching.

As before, you can make use of getFirstPage, getPreviousPage, getNextPage, and getLastPage for navigation under infinite-mode. If a page has been fetched, you can use getPage directly with the page number, an error will be thrown if the page has not been fetched yet.

By default, Backbone.PageableCollection parses the response headers to find out what the first, last, next and prev links are. The parsed links are available in the links field.

var Issues = Backbone.PageableCollection.extend({
  url: "https://api.github.com/repos/documentclound/backbone/issues?state=closed",
  mode: "infinite"

  // Initial pagination states
  state: {
    pageSize: 15,
    sortKey: "updated",
    order: 1
  },

  // You can remap the query parameters from ``state`` keys from the default
  // to those your server supports. Setting ``null`` on queryParams removed them
  // from being appended to the request URLs.
  queryParams: {
    totalPages: null,
    totalRecords: null,
    sortKey: "sort",
    order: "direction",
    directions: {
      "-1": "asc",
      "1": "desc"
    }
  }

});

var issues = new Issues();

issues.getFirstPage().done(function () {
   // do something interesting...
});

If your server API does not return the links using the Link header like Github does, you can subclass Backbone.PageableCollection to override the parseLinks methods to return a links object.

var FBComment = Backbone.Model.extend({});

var FBComments = Backbone.PageableCollection.extend({
  model: FBComment,
  url: "https://graph.facebook.com/A_REALLY_LONG_FACEBOOK_OBJECT_ID",
  mode: "infinite",
  // Set the indices to 0-based for Graph API.
  state: {
    firstPage: 0
  },
  queryParams: {
    pageSize: "limit",
    // Setting a parameter mapping value to null removes it from the query string
    currentPage: null,
    // Any extra query string parameters are sent as is, values can be functions,
    // which will be bound to the pageable collection instance temporarily
    // when called.
    offset: function () { return this.state.currentPage * this.state.pageSize; }
  },
  // Return all the comments for this Facebook object
  parse: function (resp) {
    return resp.comments;
  },
  // Facebook's `paging` object is in the exact format
  // `Backbone.PageableCollection` accepts.
  parseLinks: function (resp, xhr) {
    return resp.comments.paging;
  }
});

Sorting

Sorting has been drastically simplified in the 1.0 release while retaining the full power it had in older versions.

The main way to define a sorting for a pageable collection is to utilize the setSorting method. Given a sortKey and an order, setSorting sets state.sortKey and state.order to the given values. If order is not given, state.order is assumed. By default a comparator is applied to the full collection under client mode. Calling sort on the full collection will then get the entire pageable collection sorted globally. When operating under server or infinite mode, no comparator will be applied to the collection as sorting is assumed to be done on the server by default. Set options.full to false to apply a comparator to the current page under any mode. To sort a pageable collection under infinite mode on the client side, set options.side to "client" will apply a comparator to the full collection.

Setting sortKey to null removes the comparator from both the current page and the full collection.

var books = new Books([
  ...
], {
  mode: "client"
});

// Sets a comparator on `#fullCollection` that sorts the title in ascending
// order
books.setSorting("title");

// Don't forget to call `sort` just like you would on a `Backbone.Collection`
books.fullCollection.sort();

// Clears the comparator
books.setSorting(null);

// Sets a comparator on the current page that sorts the title in descending
// order
books.setSorting("title", 1, {full: false})
books.sort();

books.switchMode("infinite");

// Sorts the books collection under infinite paging mode on the client side
books.setSorting("title", -1, {side: "client"});
books.fullCollection.sort();

books.switchMode("server");

// Sets a comparator on the current page under server mode
books.setSorting("title", {side: "client", full: false});
books.sort();

Manipulation

This is one of the areas where Backbone.PageableCollection truely shines. A Backbone.PageableCollection instance not only can do everything a plain Backbone.Collection can for the current page, in client-mode, it can also synchronize changes and events across all of the pages. For example, you can add or remove a model from either a Backbone.PageableCollection instance, which is holding the current page, or the Backbone.PageableCollection#fullCollection collection, which is a plain Backbone.Collection holding the models for all of the pages, and the pages will all update themselves to maintain within a page size. Any additions, removals, resets, model attribute changes and synchronization actions are communicated between all the pages throught the two collections.

// The books collection is initialized to start at the first page.
var books = new Books([
  // bootstrap with all of the models for all of the pages here
], {
  mode: "client"
});

// A book is added to the end of the current page, which will overflow to the
// next page and trigger an `add` event on `fullCollection`.
books.push({ name: "The Great Gatsby"});

books.fullCollection.at(books.state.currentPage - 1 * books.state.pageSize).get("name");
>>> "The Great Gatsby"

// Add a new book to the beginning of the first page.
books.fullCollection.unshift({ name: "Oliver Twist" });
books.at(0).get("name");
>>> "Oliver Twist"

API Reference

See here.

FAQ

Why another paginator?

This project was born out of the needs for a backing model for Backgrid.Paginator -an extension for the Backgrid.js project. The project needed a smart and intuitive model that is well-documented and well-tested to manage the paginator view. Upon examining the popular project Backbone.Paginator, the author has concluded that it does not satisfy the above requirements. Furthermore, the progress of the the project is too slow. The author hopes to reinvent a better wheel that is better suited and supported for Backgrid.js.
Which package managers does backbone-pageable support?

bower, CommonJS and AMD as of 0.9.0.
Why doesn't backbone-pageable support filtering?

Wheels should be reinvented only when they are crooked. backbone-pageable aims to do one thing only and does it well, which is pagination and sorting. Besides, since Backbone.PageableCollection is 100% compatible with Backbone.Collection, you can do filtering fairly easily with Backbone's built-in support for Underscore.js methods.

Change Log

1.1.6

Bugs Fixed

Fixed bug where a page of models disappeared after adding an array of models to the current page under client mode. (Issue #43).

1.1.5

Bugs Fixed

Add event handlers should be triggered before remove handlers during client mode. (Issue #42).

1.1.4

Changes

Dropped Backbone 0.9.2 support

Bugs Fixed

TypeError thrown when adding a model to an empty client mode collection. (Issue #38).
Adding with an index inserts into the wrong page under client mode. (Issue #39).

1.1.3

Bugs Fixed

Updating after fetching under infinite mode should not create useless add, remove and sort events. (Issue #34).
RangeError when emptying fullCollection during reset (Issue #37).

1.1.2

Bugs Fixed

Fix off by 1 error with hasNext and hasPrevious (Issue #32).

1.1.1

Bugs Fixed

Fix regression where fetch errors out if url is a function (Issue #30).
Fix temperatory state inconsistency when accessing state in event handlers during client mode. (Issue #27).

1.1

Bugs Fixed

Lots of fixes for infinite paging.
Fixed incompatibility with Zepto.

Enhancements

Introduced hasPrevious and hasNext for checking if the pageable collection can be paged backward or forward.
Tested against Backbone 0.9.10, jQuery 1.9 and Zepto 1.0rc1.

1.0

Bugs Fixed

Regression from 0.9.9 where mode wasn't saved after called switchMode.

Changed

makeComparator has been renamed to _makeComparator and is now a protected method.

Enhancements

Improved infinite-mode. Infinite paging mode now runs in a hybrid mode. (Issue #17).
Greatly simplified sorting. (Issue #19).

0.9.13

Bugs Fixed

pageSize cannot be larger than totalRecords.
Off by 1 problem when shifting a model to the current page after removing from fullCollection.
RangeError when removing the last element from the last page when totalPages is > 1.

0.9.12

Enhancements

Switching modes now resets the states by default.
Infinite mode now updates currentPage as well.

Bugs Fixed

state counters will now update automatically under client mode.

0.9.11

Changed

links.first and links.next is now initialized to url for infinite mode. Calling fetch in infinite mode is now equivalent to calling getNextPage.

0.9.10

Bugs Fixed

The initial call to getFirstPage will no longer fail under infinite-mode and will now default to fetch from the collection's url.
Function values in queryParams now has this bound to the collection instance when called.

0.9.9

Changed

switchMode now accepts a mode as the first parameter.
state.isClientMode is removed. There is now a new Backbone.PageableCollection#mode attribute for this purpose.
queryParams.totalRecords now maps to "total_entries".
queryParams.directions now maps to {"-1": "asc", "1": "desc"}.

Enhancements

Support extra queryParam parameters and function values.
Infinite paging.

0.9.2

This release is tested against Backbone.js 0.9.2 and 0.9.9.

Enhancements

currentPage defaults to firstPage.

0.9.1

Bugs Fixed

Instantiating a PageableCollection in client-mode without giving it any models no longer throws errors.

Enhancements

Overriding state and queryParams in a subclass's prototype now merge with the defaults in Backbone.PageableCollection.prototype.
fullCollection now respect the parent's prototype.

0.9.0

Initial release

Legal

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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