module IndexQueryBuilder

Simple DSL for building queries using filters.

This module makes it easy to fetch records from the database, specially for showing and filtering records in an index page

Constants

VERSION

Public Class Methods

query(base_scope, options={}, &block) click to toggle source

Builds a query by calling arel methods on base_scope

@param base_scope [Arel] used to build query on top of this scope @param options [Hash] @option :with [Hash] filters used to build query. Key is filter name, value is value for the filter @yield [QueryDefinition] Gives a QueryDefinition object that implements a DSL to define how to apply filters @return [Arel] returns arel object to make it easy to extend query (e.g. add pagination, etc)

Example¶ ↑

posts = IndexQueryBuilder.query Post.where(:user_id => user.id), with: { title: 'DSLs are awesome' } do |query|
  query.filter_field :posted
  query.filter_field :title, contains: :title
  query.filter_field :posted_date,
    greater_than_or_equal_to: :from_posted_date, less_than: :to_posted_date
  query.filter_field [:comments, :author, :name], equal_to: :comment_author_name

  query.order_by "posted_date DESC, posts.created_at DESC"
end

# File lib/index_query_builder.rb, line 33
def self.query(base_scope, options={}, &block)
  query_definition = QueryDefinition.new
  block.call(query_definition)

  QueryBuilder.apply(base_scope, query_definition, filters(options))
end

query_children(child_association, base_scope, options={}, &block) click to toggle source

Builds a query by calling arel methods on base_scope, but it returns children of base scope. Use this method when using same filters as when querying the parent, but want to get back all children instead. This way, you can reuse same query definition you used for IndexQueryBuilder.query.

@param child_association [Symbol] children's association name @param base_scope [Arel] used to build query on top of this scope @param options [Hash] @option options [Hash] :with filters used to build query. Key is filter name, value is value for the filter @yield [QueryDefinition] Gives a QueryDefinition object that implements a DSL to define how to apply filters @return [Arel] returns arel object to make it easy to extend query (e.g. add pagination, etc)

Example¶ ↑

comments = IndexQueryBuilder.query_children :comments, Comments, with: { title: 'DSLs are awesome' } do |query|
  query.filter_field :posted
  query.filter_field :title, contains: :title
  query.filter_field :posted_date,
    greater_than_or_equal_to: :from_posted_date, less_than: :to_posted_date
  query.filter_field [:comments, :author, :name], equal_to: :comment_author_name

  query.order_by "comment_date DESC"
end

# File lib/index_query_builder.rb, line 62
def self.query_children(child_association, base_scope, options={}, &block)
  parents = query(base_scope.eager_load(child_association), options, &block)

  children_of(parents, child_association, base_scope)
end

Private Class Methods

children_of(parents, child_association, base_scope) click to toggle source

# File lib/index_query_builder.rb, line 90
def self.children_of(parents, child_association, base_scope)
  initialize_parent_association(child_association, base_scope, parents).flat_map(&child_association)
end

filters(params) click to toggle source

# File lib/index_query_builder.rb, line 82
def self.filters(params)
  symbolize_keys(params.fetch(:with) { {} })
end

initialize_parent_association(child_association, base_scope, parents) click to toggle source

# File lib/index_query_builder.rb, line 94
def self.initialize_parent_association(child_association, base_scope, parents)
  parents.each do |parent|
    parent.public_send(child_association).each do |child|
      child.public_send("#{base_scope.name.underscore}=", parent)
    end
  end
end

symbolize_keys(params) click to toggle source

# File lib/index_query_builder.rb, line 86
def self.symbolize_keys(params)
  Hash[params.map { |key, value| [key.to_sym, value] }]
end