ChildMemberships Form UI for ActiveScaffold

An addon for ActiveScaffold adding :child_memberships form_ui.

It requires ActiveScaffold 4.0, and RecordSelect 4.0.2 if want to use :recordselect to add new columns.

Usage

ActiveScaffold allows to edit memberships on one record with :select form_ui, for either has_and_belongs_to_many, or has_many through. For example, using :select in :roles column with any of these examples would work in the same way:

class User < ApplicationRecord
  has_and_belongs_to_many :roles
end

class User < ApplicationRecord
  has_many :role_memberships
  has_many :roles, through: :role_memberships
end

class RoleMembership < ApplicationRecord
  belongs_to :user
  belongs_to :role
end

But sometimes you may have User model grouped in other model, with has_many association, and may want to edit memberships for all the users in the group.

class Group < ApplicationRecord
  has_many :users
end

This form_ui :child_memberships can be used in a :roles has_many through association:

class Group < ApplicationRecord
  has_many :users
  has_many :roles, through: :users
end
class GroupsController < ApplicationController
  active_scaffold :group do |conf|
    conf.update.columns = [:name, :roles]
    conf.columns[:roles].form_ui = :child_memberships
  end
end

Then you get a table, with all users in the group in the rows, and roles in the columns. Only the assigned roles are in the columns by default, and new column can be added with a select tag to pick a new role to assign to users:

The form_ui used to select the record of the new columns can be changed, with options for the form_ui (or column's options), with the key :add_column_ui, for example to use RecordSelect:

    conf.columns[:roles].form_ui = :child_memberships, {add_column_ui: :record_select}

If no form_ui is defined with :add_column_ui, it defaults to :select. If ui options must be passed to the form_ui, they can be added using an array with the form UI and the options hash:

    conf.columns[:roles].form_ui = :child_memberships, {add_column_ui: [:select, {include_blank: 'Pick one'}]}

The method used for the label in the rows is defined with :label_method, defaults to :to_label. For example, to use short_name method of Role model:

    conf.columns[:roles].form_ui = :child_memberships, {label_method: :short_name}

The method used for the label in the rows is defined with :child_label_method, defaults to :to_label. For example, to use first_name method of User model:

    conf.columns[:roles].form_ui = :child_memberships, {child_label_method: :first_name}

The label of the link to add a new column uses :add_label translation key, in the :active_scaffold scope. It can be changed to a string, skipping the translation, or other symbol to use other translation key, in the :active_scaffold scope. The translation can use %{model} variable to display the name of the associated model.

    conf.columns[:roles].form_ui = :child_memberships, {add_label: 'Add other role'}

If new columns are not allowed, it can be disabled using add_label: false:

    conf.columns[:roles].form_ui = :child_memberships, {add_label: false}

Overriding Helpers

The helper active_scaffold_child_memberships_members can be overrided to change the default columns rendered, instead of the assigned records only. For example to render all available roles:

def active_scaffold_child_memberships_helper(column, row_records)
  column.association.klass.all
end

The helper can use model prefix too:

def group_active_scaffold_child_memberships_helper(column, row_records)
  column.association.klass.all
end

To change the record selector for new columns, the helper active_scaffold_child_memberships_new_column can be overrided instead of using :add_column_ui. It supports model prefix too. The field should be rendered disabled, as it's a template to be cloned when the add column link is clicked:

def active_scaffold_child_memberships_new_column(column, name, source_col, ui_options)
  if column == :roles
    select_tag name, options_from_collection_for_select(Role.allowed_for(current_login), :id, :name), id: nil, disabled: true
  else
    super
  end
end

Also, the available records can be changed with the usual methods, options_for_association_conditions and association_klass_scoped, they receive the source association of the has_many through association (:roles in the example), and an empty record of the through association.

To change how checkboxes are rendered, for example, adding extra content, the helper active_scaffold_child_memberships_checkbox can be overrided. It supports model prefix too. The argument child is the record of the row, and member is the record of the column.

def active_scaffold_child_memberships_checkbox(column, source_column, child, member, name:, value:)
  if column == :roles
    safe_join [super, content_tag(:span, member.state_for(child))] 
  else
    super
  end
end