activerecord-hackery--ransack/README.md

# Ransack

[![Build Status](https://travis-ci.org/activerecord-hackery/ransack.svg)]
(https://travis-ci.org/activerecord-hackery/ransack)
[![Gem Version](https://badge.fury.io/rb/ransack.svg)]
(http://badge.fury.io/rb/ransack)

Ransack is a rewrite of [MetaSearch]
(https://github.com/activerecord-hackery/meta_search)
created by [Ernie Miller](http://twitter.com/erniemiller)
and maintained by [Ryan Bigg](http://twitter.com/ryanbigg),
[Jon Atack](http://twitter.com/jonatack) and a great group of [contributors]
(https://github.com/activerecord-hackery/ransack/graphs/contributors).
While it supports many of the same features as MetaSearch, its underlying
implementation differs greatly from MetaSearch,
and backwards compatibility is not a design goal.

Ransack enables the creation of both simple and
[advanced](http://ransack-demo.herokuapp.com/users/advanced_search)
search forms against your application's models (demo source code
[here](https://github.com/activerecord-hackery/ransack_demo)).
If you're looking for something that simplifies query generation at the model
or controller layer, you're probably not looking for Ransack (or MetaSearch,
for that matter). Try [Squeel](https://github.com/activerecord-hackery/squeel)
instead.

## Getting started

Ransack is currently compatible with Rails 3.x, 4.0, 4.1 and 4.2.

In your Gemfile, for the last officially released Ransack gem:

```ruby
gem 'ransack'
```

Or, if you would like to use the latest updates:

```ruby
gem 'ransack', github: 'activerecord-hackery/ransack'
```

The other branches (`rails-4`, `rails-4.1`, and `rails-4.2`) were each used for
developing and running Ransack with the latest upcoming version of Rails at the
time. They are smaller and possibly slightly faster because they do not have to
support previous versions of Rails and Active Record. Once support for that
Rails version is merged from the branch into Ransack master, the branch is no
longer actively maintained -- unless the open source community submits pull
requests to maintain them. You are welcome to do so!

To use one of the branches, for example the `rails-4.1` branch:

```ruby
gem 'ransack', github: 'activerecord-hackery/ransack', branch: 'rails-4.1'
```

## Usage

Ransack can be used in one of two modes, simple or advanced.

### Simple Mode

This mode works much like MetaSearch, for those of you who are familiar with
it, and requires very little setup effort.

If you're coming from MetaSearch, things to note:

  1. The default param key for search params is now `:q`, instead of `:search`.
  This is primarily to shorten query strings, though advanced queries (below)
  will still run afoul of URL length limits in most browsers and require a
  switch to HTTP POST requests. This key is [configurable]
  (https://github.com/activerecord-hackery/ransack/wiki/Configuration).

  2. `form_for` is now `search_form_for`, and validates that a Ransack::Search
  object is passed to it.

  3. Common ActiveRecord::Relation methods are no longer delegated by the
  search object. Instead, you will get your search results (an
  ActiveRecord::Relation in the case of the ActiveRecord adapter) via a call to
  `Search#result`.
  
  4. If passed `distinct: true`, `result` will generate a `SELECT DISTINCT` to
  avoid returning duplicate rows, even if conditions on a join would otherwise
  result in some.

  Please note that for many databases, a sort on an associated table's columns
  may result in invalid SQL with `distinct: true` -- in those cases, you're on
  your own, and will need to modify the result as needed to allow these queries
  to work. If `distinct: true` is causing you problems, another way to remove
  duplicates is to call `#to_a.uniq` on your collection instead (see the next
  section below).

####In your controller

```ruby
def index
  @q = Person.search(params[:q])
  @people = @q.result(distinct: true)
end
```
or without `distinct:true`, for sorting on an associated table's columns (in
this example, with preloading each Person's Articles and pagination):

```ruby
def index
  @q = Person.search(params[:q])
  @people = @q.result.includes(:articles).page(params[:page])
  # or use `to_a.uniq` to remove duplicates (can also be done in the view):
  @people = @q.result.includes(:articles).page(params[:page]).to_a.uniq
end
```

####In your view

The two primary Ransack view helpers are `search_form_for` and `sort_link`,
which are defined in
[Ransack::Helpers::FormHelper](lib/ransack/helpers/form_helper.rb).

#####Ransack's `search_form_for` helper replaces `form_for` for creating the view search form:

```erb
<%= search_form_for @q do |f| %>

  # Search if the name field contains...
  <%= f.label :name_cont %>
  <%= f.search_field :name_cont %>

  # Search if an associated articles.title starts with...
  <%= f.label :articles_title_start %>
  <%= f.search_field :articles_title_start %>

  # Attributes may be chained. Search multiple attributes for one value...
  <%= f.label :name_or_description_or_email_or_articles_title_cont %>
  <%= f.search_field :name_or_description_or_email_or_articles_title_cont %>

  <%= f.submit %>
<% end %>
```

`cont` (contains) and `start` (starts with) are just two of the available
search predicates. See [Constants]
(https://github.com/activerecord-hackery/ransack/blob/master/lib/ransack/constants.rb)
for a full list and the [wiki]
(https://github.com/activerecord-hackery/ransack/wiki/Basic-Searching)
for more information.

The `search_form_for` answer format can be set like this:
```erb
<%= search_form_for(@q, format: :pdf) do |f| %>

<%= search_form_for(@q, format: :json) do |f| %>
```

#####Ransack's `sort_link` helper creates table headers that are sortable links:

```erb
<%= sort_link(@q, :name) %>
```
Additional options can be passed after the column attribute, like a different
column title or a default sort order:

```erb
<%= sort_link(@q, :name, 'Last Name', default_order: :desc) %>
```

You can also sort on multiple fields by specifying an ordered array:

```erb
<%= sort_link(@q, :last_name, [:last_name, 'first_name asc'], 'Last Name') %>
```

In the example above, clicking the link will sort by `last_name` and then
`first_name`. Specifying the sort direction on a field in the array tells
Ransack to _always_ sort that particular field in the specified direction.

Multiple `default_order` fields may also be specified with a hash:

```erb
<%= sort_link(@q, :last_name, %i(last_name first_name),
  default_order: { last_name: 'asc', first_name: 'desc' }) %>
```

This example toggles the sort directions of both fields, by default
initially sorting the `last_name` field by ascending order, and the
`first_name` field by descending order.

### Advanced Mode

"Advanced" searches (ab)use Rails' nested attributes functionality in order to
generate complex queries with nested AND/OR groupings, etc. This takes a bit
more work but can generate some pretty cool search interfaces that put a lot of
power in the hands of your users. A notable drawback with these searches is
that the increased size of the parameter string will typically force you to use
the HTTP POST method instead of GET. :(

This means you'll need to tweak your routes...

```ruby
resources :people do
  collection do
    match 'search' => 'people#search', via: [:get, :post], as: :search
  end
end
```

... and add another controller action ...

```ruby
def search
  index
  render :index
end
```

... and update your `search_form_for` line in the view ...

```erb
<%= search_form_for @q, url: search_people_path,
                        html: { method: :post } do |f| %>
```

Once you've done so, you can make use of the helpers in [Ransack::Helpers::FormBuilder](lib/ransack/helpers/form_builder.rb) to
construct much more complex search forms, such as the one on the
[demo page](http://ransack-demo.heroku.com) (source code [here](https://github.com/activerecord-hackery/ransack_demo)).

### Ransack #search method

Ransack will try to to make `#search` available in your models, but in the case
that `#search` has already been defined, you can use `#ransack` instead. For
example the following would be equivalent:

```ruby
Article.search(params[:q])
Article.ransack(params[:q])
```

### Associations

You can easily use Ransack to search for objects in `has_many` and `belongs_to`
associations.

Given you have these associations ...

```ruby
class Employee < ActiveRecord::Base
  belongs_to :supervisor

  # has attributes first_name:string and last_name:string
end

class Department < ActiveRecord::Base
  has_many :supervisors

  # has attribute title:string
end

class Supervisor < ActiveRecord::Base
  belongs_to :department
  has_many :employees

  # has attribute last_name:string
end
```

... and a controller ...

```ruby
class SupervisorsController < ApplicationController
  def index
    @q = Supervisor.search(params[:q])
    @supervisors = @q.result.includes(:department, :employees)
  end
end
```

... you might set up your form like this ...

```erb
<%= search_form_for @q do |f| %>
  <%= f.label :last_name_cont %>
  <%= f.search_field :last_name_cont %>

  <%= f.label :department_title_cont %>
  <%= f.search_field :department_title_cont %>

  <%= f.label :employees_first_name_or_employees_last_name_cont %>
  <%= f.search_field :employees_first_name_or_employees_last_name_cont %>

  <%= f.submit "search" %>
<% end %>
...
<%= content_tag :table %>
  <%= content_tag :th, sort_link(@q, :last_name) %>
  <%= content_tag :th, sort_link(@q, 'departments.title') %>
  <%= content_tag :th, sort_link(@q, 'employees.last_name') %>
<% end %>
```

### Using Ransackers to add custom search functions via Arel

The main premise behind Ransack is to provide access to
**Arel predicate methods**. Ransack provides special methods, called
_ransackers_, for creating additional search functions via Arel. More
information about `ransacker` methods can be found [here in the wiki]
(https://github.com/activerecord-hackery/ransack/wiki/Using-Ransackers).
Feel free to contribute working `ransacker` code examples to the wiki!

### Authorization (whitelisting/blacklisting)

By default, searching and sorting are authorized on any column of your model
and no class methods/scopes are whitelisted.

Ransack adds four methods to `ActiveRecord::Base` that you can redefine as
class methods in your models to apply selective authorization:
`ransackable_attributes`, `ransackable_associations`, `ransackable_scopes` and
`ransortable_attributes`.

Here is how these four methods are implemented in Ransack:

```ruby
  # Ransackable_attributes, by default, returns all column names
  # and any defined ransackers as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransackable_attributes(auth_object = nil)
    column_names + _ransackers.keys
  end

  # Ransackable_associations, by default, returns the names
  # of all associations as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransackable_associations(auth_object = nil)
    reflect_on_all_associations.map { |a| a.name.to_s }
  end

  # Ransortable_attributes, by default, returns the names
  # of all attributes available for sorting as an array of strings.
  # For overriding with a whitelist array of strings.
  #
  def ransortable_attributes(auth_object = nil)
    ransackable_attributes(auth_object)
  end

  # Ransackable_scopes, by default, returns an empty array
  # i.e. no class methods/scopes are authorized.
  # For overriding with a whitelist array of *symbols*.
  #
  def ransackable_scopes(auth_object = nil)
    []
  end
```

Any values not returned from these methods will be ignored by Ransack, i.e.
they are not authorized.

All four methods can receive a single optional parameter, `auth_object`. When
you call the search or ransack method on your model, you can provide a value
for an `auth_object` key in the options hash which can be used by your own
overridden methods.

Here is an example that puts all this together, adapted from
[this blog post by Ernie Miller]
(http://erniemiller.org/2012/05/11/why-your-ruby-class-macros-might-suck-mine-did/).
In an `Article` model, add the following `ransackable_attributes` class method
(preferably private):

```ruby
class Article < ActiveRecord::Base

  private

  def self.ransackable_attributes(auth_object = nil)
    if auth_object == :admin
      # whitelist all attributes for admin
      super
    else
      # whitelist only the title and body attributes for other users
      super & %w(title body) 
    end
  end
end
```

Here is example code for the `articles_controller`:

```ruby
class ArticlesController < ApplicationController

  def index
    @q = Article.search(params[:q], auth_object: set_ransack_auth_object)
    @articles = @q.result
  end
  
  private

  def set_ransack_auth_object
    current_user.admin? ? :admin : nil
  end
end
```

Trying it out in `rails console`:

```ruby
> Article
=> Article(id: integer, person_id: integer, title: string, body: text) 

> Article.ransackable_attributes
=> ["title", "body"] 

> Article.ransackable_attributes(:admin)
=> ["id", "person_id", "title", "body"] 

> Article.search(id_eq: 1).result.to_sql
=> SELECT "articles".* FROM "articles"  # Note that search param was ignored!

> Article.search({ id_eq: 1 }, { auth_object: nil }).result.to_sql
=> SELECT "articles".* FROM "articles"  # Search param still ignored!

> Article.search({ id_eq: 1 }, { auth_object: :admin }).result.to_sql
=> SELECT "articles".* FROM "articles"  WHERE "articles"."id" = 1
```

That's it! Now you know how to whitelist/blacklist various elements in Ransack.

### Using Scopes/Class Methods

Continuing on from the preceding section, searching by scopes requires defining
a whitelist of `ransackable_scopes` on the model class. The whitelist should be
an array of *symbols*. By default, all class methods (e.g. scopes) are ignored.
Scopes will be applied for matching `true` values, or for given values if the
scope accepts a value:

```ruby
class Employee < ActiveRecord::Base
  scope :active, ->(boolean = true) { where(active: boolean) }
  scope :salary_gt, ->(amount) { where('salary > ?', amount) }

  # Scopes are just syntactical sugar for class methods, which may also be used:

  def self.hired_since(date)
    where('start_date >= ?', date)
  end

  private

  def self.ransackable_scopes(auth_object = nil)
    if auth_object.try(:admin?)
      # allow admin users access to all three methods
      %i(active hired_since salary_gt)
    else
      # allow other users to search on active and hired_since only
      %i(active hired_since)
    end
  end
end

Employee.search({ active: true, hired_since: '2013-01-01' })

Employee.search({ salary_gt: 100_000 }, { auth_object: current_user })
```

If the `true` value is being passed via url params or by some other mechanism
that will convert it to a string (i.e. `active: 'true'` instead of
`active: true`), the true value will *not* be passed to the scope. If you want
to pass a `'true'` string to the scope, you should wrap it in an array (i.e.
`active: ['true']`).

Scopes are a recent addition to Ransack and currently have a few caveats:
First, a scope involving child associations needs to be defined in the parent
table model, not in the child model. Second, scopes with an array as an
argument are not easily usable yet, because the array currently needs to be
wrapped in an array to function (see
[this issue](https://github.com/activerecord-hackery/ransack/issues/404)),
which is not compatible with Ransack form helpers. For this use case, it may be
better for now to use [ransackers]
(https://github.com/activerecord-hackery/ransack/wiki/Using-Ransackers) instead,
where feasible. Pull requests with solutions and tests are welcome!

### Grouping queries by OR instead of AND

The default `AND` grouping can be changed to `OR` by adding `m: 'or'` to the
query hash.

You can easily try it in your controller code by changing `params[:q]` in the
`index` action to `params[:q].try(:merge, m: 'or')` as follows:

```ruby
def index
  @q = Artist.search(params[:q].try(:merge, m: 'or'))
  @artists = @q.result
end
```
Normally, if you wanted users to be able to toggle between `AND` and `OR`
query grouping, you would probably set up your search form so that `m` was in
the URL params hash, but here we assigned `m` manually just to try it out
quickly.

Alternatively, trying it in the Rails console:

```ruby
artists = Artist.search(name_cont: 'foo', style_cont: 'bar', m: 'or')
=> Ransack::Search<class: Artist, base: Grouping <conditions: [
  Condition <attributes: ["name"], predicate: cont, values: ["foo"]>,
  Condition <attributes: ["style"], predicate: cont, values: ["bar"]>
  ], combinator: or>>

artists.result.to_sql
=> "SELECT \"artists\".* FROM \"artists\"
    WHERE ((\"artists\".\"name\" ILIKE '%foo%'
    OR \"artists\".\"style\" ILIKE '%bar%'))"
```

The combinator becomes `or` instead of the default `and`, and the SQL query
becomes `WHERE...OR` instead of `WHERE...AND`.

This works with associations as well. Imagine an Artist model that has many
Memberships, and many Musicians through Memberships:

```ruby
artists = Artist.search(name_cont: 'foo', musicians_email_cont: 'bar', m: 'or')
=> Ransack::Search<class: Artist, base: Grouping <conditions: [
  Condition <attributes: ["name"], predicate: cont, values: ["foo"]>,
  Condition <attributes: ["musicians_email"], predicate: cont, values: ["bar"]>
  ], combinator: or>>

artists.result.to_sql
=> "SELECT \"artists\".* FROM \"artists\"
    LEFT OUTER JOIN \"memberships\"
      ON \"memberships\".\"artist_id\" = \"artists\".\"id\"
    LEFT OUTER JOIN \"musicians\"
      ON \"musicians\".\"id\" = \"memberships\".\"musician_id\"
    WHERE ((\"artists\".\"name\" ILIKE '%foo%'
    OR \"musicians\".\"email\" ILIKE '%bar%'))"
```

### Using SimpleForm

If you would like to combine the Ransack and SimpleForm form builders, set the
`RANSACK_FORM_BUILDER` environment variable before Rails boots up, e.g. in
`config/application.rb` before `require 'rails/all'` as shown below (and add
`gem 'simple_form'` in your Gemfile).

```ruby
require File.expand_path('../boot', __FILE__)
ENV['RANSACK_FORM_BUILDER'] = '::SimpleForm::FormBuilder'
require 'rails/all'
```

### I18n

Ransack translation files are available in
[Ransack::Locale](lib/ransack/locale). You may also be interested in one of the
many translations for Ransack available at
http://www.localeapp.com/projects/2999.

Predicate and attribute translations in forms may be specified as follows (see
the translation files in [Ransack::Locale](lib/ransack/locale) for more examples):

locales/en.yml:
```yml
en:
  ransack:
    asc: ascending
    desc: descending
    predicates:
      cont: contains
      not_cont: not contains
      start: starts with
      end: ends with
      gt: greater than
      lt: less than
    attributes:
      person:
        name: Full Name
      article:
        title: Article Title
        body: Main Content
```

Attribute names may also be changed globally, or under `activerecord`:

```yml
en:
  attributes:
    model_name:
      model_field1: field name1
      model_field2: field name2
  activerecord:
    attributes:
      namespace/article:
        title: AR Namespaced Title
      namespace_article:
        title: Old Ransack Namespaced Title
```

## Semantic Versioning

Ransack attempts to follow semantic versioning in the format of `x.y.z`, where:

`x` stands for a major version (new features that are not backward-compatible).
`y` stands for a minor version (new features that are backward-compatible).
`z` stands for a patch (bug fixes).

In other words: `Major.Minor.Patch`.

## Contributions

To support the project:

* Use Ransack in your apps, and let us know if you encounter anything that's
broken or missing. A failing spec to demonstrate the issue is awesome. A pull
request with passing tests is even better!
* Before filing an issue or pull request, be sure to read and follow the
[Contributing Guide](CONTRIBUTING.md).
* Please use Stack Overflow or other sites for questions or discussion not
directly related to bug reports, pull requests, or documentation improvements.
* Spread the word on Twitter, Facebook, and elsewhere if Ransack's been useful
to you. The more people who are using the project, the quicker we can find and
fix bugs!

## Copyright

Copyright &copy; 2011-2014 [Ernie Miller](http://twitter.com/erniemiller)