Kaminari

A Scope & Engine based, clean, powerful, customizable and sophisticated paginator for Rails 3

Features

Clean

Does not globally pollute Array, Hash, Object or AR::Base.

Easy to use

Just bundle the gem, then your models are ready to be paginated. No configuration required. Don’t have to define anything in your models or helpers.

Simple scope-based API

Everything is method chainable with less “Hasheritis”. You know, that’s the Rails 3 way. No special collection class or anything for the paginated values, instead using a general AR::Relation instance. So, of course you can chain any other conditions before or after the paginator scope.

Customizable engine-based I18n-aware helper

As the whole pagination helper is basically just a collection of links and non-links, Kaminari renders each of them through its own partial template inside the Engine. So, you can easily modify their behaviour, style or whatever by overriding partial templates.

ORM & template engine agnostic

Kaminari supports multiple ORMs (ActiveRecord, Mongoid, MongoMapper) and multiple template engines (ERB, Haml).

Modern

The pagination helper outputs the HTML5 <nav> tag by default. Plus, the helper supports Rails 3 unobtrusive Ajax.

Supported versions

Ruby 1.8.7, 1.9.2, 1.9.3 (trunk)
Rails 3.0.x, 3.1 (edge)
Haml 3
Mongoid 2
MongoMapper 0.9

Install

Put this line in your Gemfile:

gem 'kaminari'

Then bundle:

% bundle

Usage

Query Basics

the page scope

To fetch the 7th page of users (default per_page is 25)
```
User.page(7)
```
the per scope

To show a lot more users per each page (change the per_page value)
```
User.page(7).per(50)
```
Note that the per scope is not directly defined on the models but is just a method defined on the page scope. This is absolutely reasonable because you will never actually use per_page without specifying the page number.
the smart_count method

ActiveRecord count method may fail or give wrong results on complex queries. Say, for example, you use having constraint, based on select generated columns. As long as generated columns are thrown away, having constraint will fail and you will get invalid query. If this is your case, you should define a smart_count method on your model or scope. A possible implementation may be (works with any complex query):
```
def smart_count
  count_by_sql("SELECT COUNT(*) FROM (#{scoped.to_sql}) AS count_table")
end
```
Kaminari will call this method instead of count if it is defined.

General configuration options

You can configure the following default values by overriding these values using Kaminari.configure method.

default_per_page  # 25 by default
window            # 4 by default
outer_window      # 0 by default
left              # 0 by default
right             # 0 by default

There’s a handy generator that generates the default configuration file into config/initializers directory. Run the following generator command, then edit the generated file.

% rails g kaminari:config

Configuring default `per_page` value for each model

paginates_per

You can specify default per_page value per each model using the following declarative DSL.
```
class User < ActiveRecord::Base
  paginates_per 50
end
```

Controllers

the page parameter is in params[:page]

Typically, your controller code will look like this:
```
@users = User.order(:name).page params[:page]
```

Views

the same old helper method

Just call the paginate helper:
```
<%= paginate @users %>
```
This will render several ?page=N pagination links surrounded by an HTML5 <nav> tag.

Helper Options

specifing the “inner window” size (4 by default)
```
<%= paginate @users, :window => 2 %>
```
This would output something like ... 5 6 7 8 9 ... when 7 is the current page.
specifing the “outer window” size (0 by default)
```
<%= paginate @users, :outer_window => 3 %>
```
This would output something like 1 2 3 4 ...(snip)... 17 18 19 20 while having 20 pages in total.
outer window can be separetely specified by left, right (0 by default)
```
<%= paginate @users, :left => 1, :right => 3 %>
```
This would output something like 1 ...(snip)... 18 19 20 while having 20 pages in total.
changing the parameter name (:param_name) for the links
```
<%= paginate @users, :param_name => :pagina %>
```
This would modify the query parameter name on each links.
extra parameters (:params) for the links
```
<%= paginate @users, :params => {:controller => 'foo', :action => 'bar'} %>
```
This would modify each link’s url_option. :controller and :action might be the keys in common.
Ajax links (crazy simple, but works perfectly!)
```
<%= paginate @users, :remote => true %>
```
This would add data-remote="true" to all the links inside.

I18n and labels

The default labels for ‘previous’, ‘…’ and ‘next’ are stored in the I18n yaml inside the engine, and rendered through I18n API. You can switch the label value per I18n.locale for your internationalized application. Keys and the default values are the following. You can override them by adding to a YAML file in your Rails.root/config/locales directory.

en:
  views:
    pagination:
      previous: "&laquo; Prev"
      next: "Next &raquo;"
      truncate: "..."

Customizing the pagination helper

Kaminari includes a handy template generator.

to edit your paginator

Run the generator first,
```
% rails g kaminari:views default
```
then edit the partials in your app’s app/views/kaminari/ directory.
for Haml users

Haml templates generator is also available by adding the -e haml option (this is automatically invoked when the default template_engine is set to Haml).
```
% rails g kaminari:views default -e haml
```
themes

The generator has the ability to fetch several sample template themes from the external repository (github.com/amatsuda/kaminari_themes) in addition to the bundled “default” one, which will help you creating a nice looking paginator.
```
% rails g kaminari:views THEME
```
To see the full list of avaliable themes, take a look at the themes repository, or just hit the generator without specifying THEME argument.
```
% rails g kaminari:views
```
multiple themes

To utilize multiple themes from within a single application, create a directory within the app/views/kaminari/ and move your custom template files into that directory.
```
% rails g kaminari:views default (skip if you have existing kaminari views)
% cd app/views/kaminari
% mkdir my_custom_theme
% cp _*.html.* my_custom_theme/
```
Next reference that directory when calling the paginate method:
```
<%= paginate @users, :theme => 'my_custom_theme' %>
```
Customize away!

Note: if the theme isn’t present or none is specified, kaminari will default back to the views included within the gem.

Paginating a generic Array object

Kaminari provides an Array wrapper class that adapts a generic Array object to the paginate view helper. However, the paginate helper doesn’t automatically handle your Array object (this is an intensional design). Kaminari::paginate_array method converts your Array object into a paginatable Array that accepts page method.

Kaminari.paginate_array(my_array_object).page(params[:page]).per(10)

For more information

Check out Kaminari recipes on the GitHub Wiki for more advanced tips and techniques. github.com/amatsuda/kaminari/wiki/Kaminari-recipes

Questions, Feedback

Feel free to message me on Github (amatsuda) or Twitter (@a_matsuda) ☇☇☇ :)

Contributing to Kaminari

Fork, fix, then send me a pull request.