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A minimal, object-oriented solution to generate Rails administrative index views. Through query objects and presenters, it features a customizable table generator and search forms with filtering/sorting.

The philosophy behind it

The Rails ecosystem has many full-fledged solutions to generate administrative interfaces.

Although these tools are very handy to bootstrap a project quickly, they all obey the 80%-20% rule and tend to be very invasive, often mixing up different concerns on a single responsibility level, thus making tests unbelievably difficult to setup and write.

A time comes when these all-encompassing tools get in the way. And that will be the moment where all the cumulated saved time will be wasted to solve a single, trivial problem with ugly workarounds and epic facepalms.

So yes, if you’re starting a small, short-lived project, go ahead with them, it will be fine! If you’re building something that’s more valuable or is meant to last longer, there are better alternatives.

A modular approach to the problem

The great thing is that you don’t need to write a lot of code to get a more maintainable and modular administrative area. Gems like Inherited Resources and Simple Form, combined with Rails 3.1+ template-inheritance already give you ~90% of the time-saving features and the same super-DRY, declarative code that administrative interfaces offer, but with a far more relaxed contract.

If a particular controller or view needs something different from the standard CRUD/REST treatment, you can just avoid using those gems in that specific context, and fall back to standard Rails code. No workarounds, no facepalms. It seems easy, right? It is.

So what about Admino? Well, it complements the above-mentioned gems, giving you the the missing ~10%: a fast way to generate administrative index views.

Demo

To better illustrate how to create a 100%-custom, super-DRY administrative interface using Admino and the aforementioned gems, we prepared a repo with a sample Rails project you can take a look. The app is browsable at http://admino-example.herokuapp.com, and features a Bootstrap 3 theme.

Installation

Add this line to your application’s Gemfile:

gem 'admino'

And then execute:

$ bundle

Admino::Query::Base

Admino::Query::Base implements the Query object pattern, that is, an object responsible for returning a result set (ie. an ActiveRecord::Relation) based on business rules.

Given a Task model, we can generate a TasksQuery query object subclassing Admino::Query::Base:

“by class TasksQuery < Admino::Query::Base end

“

Each query object gets initialized with a hash of params, and features a #scope method that returns the filtered/sorted result set. As you may have guessed, query objects can be great companions to index actions:

“by class TasksController < ApplicationController def index @query = TasksQuery.new(params) @tasks = @query.scope end end

“

Building the query itself

You can specify how a TaskQuery must build a result set through a simple DSL.

starting_scope

The starting_scope method is in charge of defining the scope that will start the filtering/ordering chain:

“by class TasksQuery < Admino::Query::Base starting_scope { Task.all } end

Task.create(title: ‘Low priority task’)

TaskQuery.new.scope.count # => 1

“

search_field

Once you define the following field:

“by class TasksQuery < Admino::Query::Base # … search_field :title_matches end

“

The #scope method will check the presence of the params[:query][:title_matches] key. If it finds it, it will augment the query with a named scope called :title_matches, expected to be found within the Task model. The scope needs to accept an argument.

“by class Task < ActiveRecord::Base scope :title_matches, ->(text) { where(‘title ILIKE ?’, “%#text%”) } end

Task.create(title: ‘Low priority task’) Task.create(title: ‘Fix me ASAP!!1!’)

TaskQuery.new.scope.count # => 2 TaskQuery.new(query: { title_matches: ‘ASAP’ }).scope.count # => 1

“

You can provide a default value with the default option:

“by class TasksQuery < Admino::Query::Base # … search_field :title_matches, default: ‘TODO’ end

“

filter_by

“by class Task < ActiveRecord::Base enum :status, [:pending, :completed, :archived] scope :title_matches, ->(text) { where(‘title ILIKE ?’, “%#text%”) } end

class TasksQuery < Admino::Query::Base # … filter_by :status, [:completed, :pending] filter_by :deleted, [:with_deleted] filter_by :status, Task.statuses.keys end

“

Just like a search field, with a declared filter group the #scope method will check the presence of a params[:query][:status] key. If it finds it (and its value corresponds to one of the declared scopes) it will augment the query with the scope itself:

“by class Task < ActiveRecord::Base scope :completed, -> { where(completed: true) } scope :pending, -> { where(completed: false) } end

Task.create(title: ‘First task’, completed: true) Task.create(title: ‘Second task’, completed: true) Task.create(title: ‘Third task’, completed: false)

TaskQuery.new.scope.count # => 3 TaskQuery.new(query: { status: ‘completed’ }).scope.count # => 2 TaskQuery.new(query: { status: ‘pending’ }).scope.count # => 1 TaskQuery.new(query: { status: ‘foobar’ }).scope.count # => 3

“

You can include a “reset” scope with the include_empty_scope option, and provide a default scope with the default option:

“by class TasksQuery < Admino::Query::Base # … filter_by :time, [:last_month, :last_week], include_empty_scope: true, default: :last_week end

“

sorting

“by class TasksQuery < Admino::Query::Base # … sorting :by_due_date, :by_title end

“

Once you declare some sorting scopes, the query object looks for a params[:sorting] key. If it exists (and corresponds to one of the declared scopes), it will augment the query with the scope itself. The model named scope will be called passing an argument that represents the direction of sorting (:asc or :desc).

The direction passed to the scope will depend on the value of params[:sort_order], and will default to :asc:

“by class Task < ActiveRecord::Base scope :by_due_date, ->(direction) { order(due_date: direction) } scope :by_title, ->(direction) { order(title: direction) } end

expired_task = Task.create(due_date: 1.year.ago) future_task = Task.create(due_date: 1.week.since)

TaskQuery.new(sorting: ‘by_due_date’, sort_order: ‘desc’).scope # => [future_task, expired_task] TaskQuery.new(sorting: ‘by_due_date’, sort_order: ‘asc’).scope # => [expired_task, future_task] TaskQuery.new(sorting: ‘by_due_date’).scope # => [expired_task, future_task]

“

ending_scope

It’s very common ie. to paginate a result set. The block declared in the ending_scope block will be always appended to the end of the chain:

“by class TasksQuery < Admino::Query::Base ending_scope { |q| page(q.params[:page]) } end

“

Let the query object do the chaining

If you do not want to pollute your ActiveRecord model with all these scopes, you are free to implement them on the query object itself (just make sure to suffix them with _scope):

“by class Task < ActiveRecord::Base end

class TasksQuery < Admino::Query::Base search_field :title_matches

def title_matches_scope(scope, text) scope.where(‘title ILIKE ?’, “%#text%”) end end

“

Inspecting the query state

A query object supports various methods to inspect the available search fields, filters and sortings, and their state:

“by query = TaskQuery.new query.search_fields # => [#, ] query.filter_groups # => [#, ]

search_field = query.search_field_by_name(:title_matches)

search_field.name # => :title_matches search_field.present? # => true search_field.value # => ‘ASAP’

filter_group = query.filter_group_by_name(:status)

filter_group.name # => :status filter_group.scopes # => [:completed, :pending] filter_group.active_scope # => :completed filter_group.is_scope_active?(:pending) # => false

sorting = query.sorting # => #Admino::Query::Sorting sorting.scopes # => [:by_title, :by_due_date] sorting.active_scope # => :by_due_date sorting.is_scope_active?(:by_title) # => false sorting.ascending? # => true

“

Presenting search form and filters to the user

Admino offers some helpers that make it really easy to generate search forms and filtering links:

“b <%# generate the search form %> <%= search_form_for(query) do |q| %> <%# generate inputs from search_fields %> 

Maruku could not parse this XML/HTML: 
<p>

<%# generate the filtering links %> <% filters_for(query) do |filter_group| %> 

Maruku could not parse this XML/HTML: 
<h6>

Maruku could not parse this XML/HTML: 
<%# generate the sorting links %>
<h6>Sort by</h6>
Maruku could not parse this XML/HTML: 
<ul>
  <% sortings_for(query) do |scope| %>
    <li><%= scope.link %></li>
  <% end %>
</ul>

“he great thing is that:

  • the search form gets automatically filled in with the last input the user submitted
  • a is-active CSS class gets added to the currently active filter scopes
  • if a particular filter link has been clicked and is now active, it is possible to deactivate it by clicking on the link again
  • a is-asc/is-desc CSS class gets added to the currently active sorting scope
  • if a particular sorting scope link has been clicked and is now in ascending order, it is possible to make it descending by clicking on the link again

Simple Form support

If you prefer using Simple Form, please use the simple_search_form_for helper instead.

Output customization

The #link methods are very flexible, allowing you to change almost every aspect of the generated links:

“b <% filter_group.each_scope do |scope| %> 

Maruku could not parse this XML/HTML: 
<li>

“

Please refer to the tests for the details.

Overwriting the starting scope

Suppose you have to filter the tasks based on the @current_user work group. You can easily provide an alternative starting scope from the controller passing it as an argument to the #scope method:

“by def index @query = TasksQuery.new(params) @project_tasks = @query.scope(@current_user.team.tasks) end

“

Coertions

Suppose the presence of a model scope that requires a non-textual argument (ie. a date):

“by class Task < ActiveRecord::Base scope :due_date_from, ->(date) { where(‘due_date >= ?’, date) } end

“

Admino can perform some automatic coertions to the textual parameter it gets, and pass the coerced value to the scope:

“by class TasksQuery < Admino::Query::Base search_field :due_date_from, coerce: :to_date end

query = TaskQuery.new(query: { due_date_from: ‘2014-03-01’ }) query.search_field_by_name(:due_date_from).value # => #

Maruku could not parse this XML/HTML: 
<Date Sat, 01 Mar 2014>

“

If a specific coercion cannot be performed with the provided input, the scope won’t be chained. The following coertions are available:

  • :to_boolean
  • :to_constant
  • :to_date
  • :to_datetime
  • :to_decimal
  • :to_float
  • :to_integer
  • :to_symbol
  • :to_time

Please see the Coercible::Coercer::String class for details.

Default sorting

If you need to setup a default sorting, you can pass some optional arguments to the sorting declaration:

“by class TasksQuery < Admino::Query::Base # … sorting :by_due_date, :by_title, default_scope: :by_due_date, default_direction: :desc end

“

I18n

To localize the search form labels, as well as the group filter names and scope links, please refer to the following YAML file:

“ml en: query: attributes: tasks_query: title_matches: ‘Title contains’ filter_groups: tasks_query: status: name: ‘Filter by status’ scopes: completed: ‘Completed’ pending: ‘Pending’ sorting_scopes: task_query: by_due_date: ‘By due date’ by_title: ‘By title’

“

Admino::Table::Presenter

Admino offers a table_for helper that makes it really easy to generate HTML tables from a set of records:

“b <%= table_for(@tasks, class: Task) do |row, record| %> <%= row.column :title %> <%= row.column :completed do %> <%= record.completed ? ‘✓’ : ‘✗’ %> <% end %> <%= row.column :due_date %> <% end %>

“

With produces the following output:

“ml <table> <thead> Title Completed Due date <thead> <tbody> Call mum ASAP ✓ 2013-02-04 <tbody> </table>

“

Record actions

Often tables need to offer some kind of action associated with the records. The table builder implements the following DSL to support that:

“b <%= table_for(@tasks, class: Task) do |row, record| %> <%# … %> <%= row.actions do %> <%= row.action :show, admin_task_path(record) %> <%= row.action :edit, edit_admin_task_path(record) %> <%= row.action :destroy, admin_task_path(record), method: :delete %> <% end %> <% end %>

“

“ml <table> <thead> Actions <thead> <tbody> Show Edit Destroy <tbody> </table>

“

Sortable columns

If you want to make the table headers sortable, then please create an Admino query object class to define the available sorting scopes.

“by class TaskQuery < Admino::Query::Base sorting :by_title, :by_due_date end

“

You can then pass the query object as a parameter to the table presenter initializer, and associate table columns to specific sorting scopes of the query object using the sorting directive:

“b <% query = present(@query) %>

<%= table_for(@tasks, class: Task) do |row, record| %> <%= row.column :title, sorting: :by_title %> <%= row.column :due_date, sorting: :by_due_date %> <% end %>

“

This generates links that allow the visitor to sort the result set in ascending and descending direction:

“ml <table> <thead> 

Maruku could not parse this XML/HTML: 
<tr>
      <th role='title'>
        <a href='/admin/tasks?sorting=by_title&sort_order=desc' class='is-asc'>Title</a>
      </th>
      <th role='due-date'>
        <a href='/admin/tasks?sorting=by_due_date&sort_order=asc'>Due date</a>
      </th>
    </tr>
<thead> </table>

“

Customizing the output

The #column and #action methods are very flexible, allowing you to change almost every aspect of the generated table cells:

“b <%= table_for(@tasks, class: Task, html: { class: ‘table-class’ }) do |row, record| %> <%= row.column :title, ‘Custom title’, class: ‘custom-class’, role: ‘custom-role’, data: { custom: ‘true’ }, sorting: :by_title, sorting_html_options: { desc_class: ‘down’ } %> <%= row.action :show, admin_task_path(record), ‘Custom label’, class: ‘custom-class’, role: ‘custom-role’, data: { custom: ‘true’ } %> <% end %>

“

If you need more power, you can also subclass Admino::Table::Presenter. For each HTML element, there’s a set of methods you can override to customize it’s appeareance. Table cells are generated through two collaborator classes: Admino::Table::HeadRow and Admino::Table::ResourceRow. You can easily replace them with a subclass if you want. To grasp the idea here’s an example:

“by class CustomTablePresenter < Admino::Table::Presenter private

def table_html_options { class: ‘table-class’ } end

def tbody_tr_html_options(resource, index) { class: ‘tr-class’ } end

def zebra_css_classes %w(one two three) end

def resource_row(resource, view_context) ResourceRow.new(resource, view_context) end

def head_row(collection_klass, query, view_context) HeadRow.new(collection_klass, query, view_context) end

class ResourceRow < Admino::Table::ResourceRow private

def action_html_options(action_name)
  { class: 'action-class' }
end

def show_action_html_options
  { class: 'show-action-class' }
end

def column_html_options(attribute_name)
  { class: 'column-class' }
end

end

class HeadRow < Admino::Table::ResourceRow def column_html_options(attribute_name) { class: ‘column-class’ } end end end

“

“b <%= table_for(@tasks, class: Task, presenter: CustomTablePresenter) do |row, record| %> <%= row.column :title, ‘Custom title’, class: ‘custom-class’, role: ‘custom-role’, data: { custom: ‘true’ }, sorting: :by_title, sorting_html_options: { desc_class: ‘down’ } %> <%= row.action :show, admin_task_path(record), ‘Custom label’, class: ‘custom-class’, role: ‘custom-role’, data: { custom: ‘true’ } %> <% end %>

“

Please refer to the tests for all the details.

Inherited resources (and similar)

If your controller actions are generated through Inherited Resources, then you can always get the URL pointing to the show action with the resource_path helper method. Similar helpers are available for the other REST actions too (new, edit, destroy).

More in general, if you are able to programmatically generate/obtain the URLs of your row actions, you can subclass Admino::Table::Presenter and declare them:

“by class CustomTablePresenter < Admino::Table::Presenter private

def resource_row(resource, view_context) ResourceRow.new(resource, view_context) end

class ResourceRow < Admino::Table::ResourceRow def show_action_url h.resource_url(resource) end

def edit_action_url
  h.edit_resource_url(resource)
end

def destroy_action_url
  h.resource_url(resource)
end

def destroy_action_html_options
  { method: :delete }
end

end end

“

This will enable you to generate row actions even faster, simply declaring them as arguments to the #actions DSL method:

“b <%= table_for(@tasks, class: Task, presenter: CustomTablePresenter) do |row, record| %> <%# … %> <%= row.actions :show, :edit, :destroy %> <% end %>

“

Showcase::Traits::Record

As funny it may sound, it is strongly suggested to pass to the table presenter an array of records which in turn have been already presented. This enables you to use as columns not only the raw attributes of the model, but all the methods defined in the presenter.

Furthermore, if the record presenter includes the Showcase::Traits::Record trait, each row of the table will automatically have an unique id attribute thanks to the #dom_id method.

“by class TaskPresenter < Showcase::Presenter include Showcase::Traits::Record

def truncated_title h.truncate(title, length: 50) end end

“

“b <% tasks = present_collection(@tasks)

<%= Admino::Table::Presenter.new(tasks, Task, self).to_html do |row, record| %> <%= row.column :truncated_title, ‘Title’ %> <% end %>

“

“ml <table> <thead> Title <thead> <tbody> Call mum ASAP Buy some milk <tbody> </table>

“

I18n

Column titles are generated using the model #human_attribute_name method, so if you already translated the model attribute names, you’re good to go. To translate actions, please refer to the following YAML file:

“ml en: activerecord: attributes: task: title: ‘Title’ due_date: ‘Due date’ completed: ‘Completed?’ table: actions: task: title: ‘Actions’ show: ‘Details’ edit: ‘Edit task’ destroy: ‘Delete’

“

Running tests

Install gems:

“ bundle $ bundle exec appraisal

“

Launch tests:

“undle exec appraisal rake

“