Admino

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.

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:

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 controller actions:

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:

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:

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, that needs to accept an argument.

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

`filter_by`

class TasksQuery < Admino::Query::Base
  # ...
  filter_by :status, [:completed, :pending]
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 the scope itself:

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

`sorting`

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:

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:

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

Inspecting the query state

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

query = TaskQuery.new
query.search_fields  # => [ #<Admino::Query::SearchField>, ... ]
query.filter_groups  # => [ #<Admino::Query::FilterGroup>, ... ]

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

Admino also offers a Showcase presenter that makes it really easy to generate search forms and filtering links:

<%# instanciate the the query object presenter %>
<% query = present(@query) %>

<%# generate the search form %>
<%= query.form do |q| %>
  <p>
    <%= q.label :title_matches %>
    <%= q.text_field :title_matches %>
  </p>
  <p>
    <%= q.submit %>
  </p>
<% end %>

<%# generate the filtering links %>
<% query.filter_groups.each do |filter_group| %>
  <h6><%= filter_group.name %></h6>
  <ul>
    <% filter_group.scopes.each do |scope| %>
      <li>
        <%= filter_group.scope_link(scope) %>
      <li>
    <% end %>
  </ul>
<% end %>

<%# generate the sorting links %>
<h6>Sort by</h6>
<ul>
  <% query.sorting.scopes.each do |scope| %>
    <li>
      <%= query.sorting.scope_link(scope) %>
    </li>
  <% end %>
</ul>

The 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

The presenter also offers a #simple_form method to make it work with Simple Form out of the box.

I18n

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

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'

Output customization

The presenter supports a number of optional arguments that allow a great amount of flexibility regarding customization of CSS classes, labels and HTML attributes. 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:

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

Coertions

Admino can perform automatic coertions from a param string input to the type needed by the model named scope:

class TasksQuery < Admino::Query::Base
  # ...
  field :due_date_from, coerce: :to_date
  field :due_date_to, coerce: :to_date
end

The following coertions are available:

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

If a specific coercion cannot be performed with the provided input, the scope won't be chained.

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 a scoping declaration:

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

Admino::Table::Presenter

Admino offers a Showcase collection presenter that makes it really easy to generate HTML tables from a set of records:

<%= Admino::Table::Presenter.new(@tasks, Task, self).to_html do |row, record| %>
  <%= row.column :title %>
  <%= row.column :completed do %>
    <%= record.completed ? '✓' : '✗' %>
  <% end %>
  <%= row.column :due_date %>
<% end %>

<table>
  <thead>
    <tr>
      <th role='title'>Title</th>
      <th role='completed'>Completed</th>
      <th role='due_date'>Due date</th>
    </tr>
  <thead>
  <tbody>
    <tr id='task_1' class='is-even'>
      <td role='title'>Call mum ASAP</td>
      <td role='completed'>✓</td>
      <td role='due_date'>2013-02-04</td>
    </tr>
    <tr id='task_2' class='is-odd'>
      <!-- ... -->
    </tr>
  <tbody>
</table>

Record actions

Often table rows needs to offer some kind of action associated with the record. The presenter implements the following DSL to support that:

<%= Admino::Table::Presenter.new(@tasks, Task, self).to_html 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 %>

<table>
  <thead>
    <tr>
      <!-- ... -->
      <th role='actions'>Actions</th>
    </tr>
  <thead>
  <tbody>
    <tr id='task_1' class='is-even'>
      <!-- ... -->
      <td role='actions'>
        <a href='/admin/tasks/1' role='show'>Show</a>
        <a href='/admin/tasks/1/edit' role='edit'>Edit</a>
        <a href='/admin/tasks/1' role='destroy' data-method='delete'>Destroy</a>
      </td>
    </tr>
  <tbody>
</table>

Sortable columns

Once a query object is passed to the presenter, columns can be associated to specific sorting scopes of the query object using the sorting option:

<% query = present(@query) %>

<%= Admino::Table::Presenter.new(@tasks, Task, query, self).to_html 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:

<table>
  <thead>
    <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" class='is-asc'>Due date</a>
      </th>
    </tr>
  <thead>
  <!-- ... -->
</table>

Customizing the output

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

<%= Admino::Table::Presenter.new(@tasks, Task, self).to_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 decide to 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:

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

Please refer to the tests for all the details.

Inherited resources

If the action URLs can be programmatically generated, it becomes even easier to specify the table actions:

<%= CustomTablePresenter.new(@tasks, Task, self).to_html do |row, record| %>
  <%# ... %>
  <%= row.actions :show, :edit, :destroy %>
<% end %>

For instance, using Inherited Resources to generate controller actions, you can use its helper methods to build a custom subclass of Admino::Table::Presenter:

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

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:

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

Admino

The philosophy behind it

A modular approach to the problem

Installation

Admino::Query::Base

Building the query itself

starting_scope

search_field

filter_by

sorting

ending_scope

Inspecting the query state

Presenting search form and filters to the user

Simple Form support

I18n

Output customization

Overwriting the starting scope

Coertions

Default sorting

Admino::Table::Presenter

Record actions

Sortable columns

Customizing the output

Inherited resources

I18n

`starting_scope`

`search_field`

`filter_by`

`sorting`

`ending_scope`