# File lib/active_record/relation/query_methods.rb, line 259 def arel @arel ||= with_default_scope.build_arel end
# File lib/active_record/relation/query_methods.rb, line 126 def bind(value) relation = clone relation.bind_values += [value] relation end
# File lib/active_record/relation/query_methods.rb, line 263 def build_arel arel = table.from table build_joins(arel, @joins_values) unless @joins_values.empty? collapse_wheres(arel, (@where_values - ['']).uniq) arel.having(*@having_values.uniq.reject{|h| h.blank?}) unless @having_values.empty? arel.take(connection.sanitize_limit(@limit_value)) if @limit_value arel.skip(@offset_value.to_i) if @offset_value arel.group(*@group_values.uniq.reject{|g| g.blank?}) unless @group_values.empty? order = @order_values order = reverse_sql_order(order) if @reverse_order_value arel.order(*order.uniq.reject{|o| o.blank?}) unless order.empty? build_select(arel, @select_values.uniq) arel.distinct(@uniq_value) arel.from(@from_value) if @from_value arel.lock(@lock_value) if @lock_value arel end
# File lib/active_record/relation/query_methods.rb, line 179 def create_with(value) relation = clone relation.create_with_value = value ? create_with_value.merge(value) : {} relation end
# File lib/active_record/relation/query_methods.rb, line 25 def eager_load(*args) return self if args.blank? relation = clone relation.eager_load_values += args relation end
Used to extend a scope with additional methods, either through a module or through a block provided.
The object returned is a relation, which can be further extended.
module Pagination def page(number) # pagination code goes here end end scope = Model.scoped.extending(Pagination) scope.page(params[:page])
You can also pass a list of modules:
scope = Model.scoped.extending(Pagination, SomethingElse)
scope = Model.scoped.extending do def page(number) # pagination code goes here end end scope.page(params[:page])
You can also use a block and a module list:
scope = Model.scoped.extending(Pagination) do def per_page(number) # pagination code goes here end end
# File lib/active_record/relation/query_methods.rb, line 243 def extending(*modules) modules << Module.new(&Proc.new) if block_given? return self if modules.empty? relation = clone relation.send(:apply_modules, modules.flatten) relation end
# File lib/active_record/relation/query_methods.rb, line 185 def from(value) relation = clone relation.from_value = value relation end
# File lib/active_record/relation/query_methods.rb, line 80 def group(*args) return self if args.blank? relation = clone relation.group_values += args.flatten relation end
# File lib/active_record/relation/query_methods.rb, line 140 def having(opts, *rest) return self if opts.blank? relation = clone relation.having_values += build_where(opts, rest) relation end
# File lib/active_record/relation/query_methods.rb, line 15 def includes(*args) args.reject! {|a| a.blank? } return self if args.empty? relation = clone relation.includes_values = (relation.includes_values + args).flatten.uniq relation end
# File lib/active_record/relation/query_methods.rb, line 115 def joins(*args) return self if args.compact.blank? relation = clone args.flatten! relation.joins_values += args relation end
# File lib/active_record/relation/query_methods.rb, line 148 def limit(value) relation = clone relation.limit_value = value relation end
# File lib/active_record/relation/query_methods.rb, line 160 def lock(locks = true) relation = clone case locks when String, TrueClass, NilClass relation.lock_value = locks || true else relation.lock_value = false end relation end
# File lib/active_record/relation/query_methods.rb, line 154 def offset(value) relation = clone relation.offset_value = value relation end
# File lib/active_record/relation/query_methods.rb, line 88 def order(*args) return self if args.blank? relation = clone relation.order_values += args.flatten relation end
# File lib/active_record/relation/query_methods.rb, line 33 def preload(*args) return self if args.blank? relation = clone relation.preload_values += args relation end
# File lib/active_record/relation/query_methods.rb, line 173 def readonly(value = true) relation = clone relation.readonly_value = value relation end
Replaces any existing order defined on the relation with the specified order.
User.order('email DESC').reorder('id ASC') # generated SQL has 'ORDER BY id ASC'
Subsequent calls to order on the same relation will be appended. For example:
User.order('email DESC').reorder('id ASC').order('name ASC')
generates a query with 'ORDER BY id ASC, name ASC'.
# File lib/active_record/relation/query_methods.rb, line 106 def reorder(*args) return self if args.blank? relation = clone relation.reordering_value = true relation.order_values = args.flatten relation end
# File lib/active_record/relation/query_methods.rb, line 253 def reverse_order relation = clone relation.reverse_order_value = !relation.reverse_order_value relation end
Works in two unique ways.
First: takes a block so it can be used just like Array#select.
Model.scoped.select { |m| m.field == value }
This will build an array of objects from the database for the scope, converting them into an array and iterating through them using Array#select.
Second: Modifies the SELECT statement for the query so that only certain fields are retrieved:
>> Model.select(:field) => [#<Model field:value>]
Although in the above example it looks as though this method returns an array, it actually returns a relation object and can have other query methods appended to it, such as the other methods in ActiveRecord::QueryMethods.
The argument to the method can also be an array of fields.
>> Model.select([:field, :other_field, :and_one_more]) => [#<Model field: "value", other_field: "value", and_one_more: "value">]
Any attributes that do not have fields retrieved by a select will raise a ActiveModel::MissingAttributeError when the getter method for that attribute is used:
>> Model.select(:field).first.other_field => ActiveModel::MissingAttributeError: missing attribute: other_field
# File lib/active_record/relation/query_methods.rb, line 70 def select(value = Proc.new) if block_given? to_a.select {|*block_args| value.call(*block_args) } else relation = clone relation.select_values += Array.wrap(value) relation end end
Specifies whether the records should be unique or not. For example:
User.select(:name) # => Might return two records with the same name User.select(:name).uniq # => Returns 1 record per unique name User.select(:name).uniq.uniq(false) # => You can also remove the uniqueness
# File lib/active_record/relation/query_methods.rb, line 201 def uniq(value = true) relation = clone relation.uniq_value = value relation end
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