Arel: Add support for FILTER clause (SQL:2003)
Currently supported by PostgreSQL 9.4+ and SQLite 3.30+ See: - http://modern-sql.com/feature/filter - https://www.postgresql.org/docs/9.4/static/sql-expressions.html#SYNTAX-AGGREGATES - https://sqlite.org/lang_aggfunc.html#aggfilter Example: Model.all.pluck( Arel.star.count.as('records_total').to_sql, Arel.star.count.filter(Model.arel_table[:some_column].not_eq(nil)).as('records_filtered').to_sql, )
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@ -1,3 +1,23 @@
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* Arel: Add support for FILTER clause (SQL:2003)
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Currently supported by PostgreSQL 9.4+ and SQLite 3.30+
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Example usage:
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Model.all.pluck(
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Arel.star.count.as('records_total').to_sql,
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Arel.star.count.filter(Model.arel_table[:some_column].not_eq(nil)).as('records_filtered').to_sql,
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)
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Example result:
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SELECT
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COUNT(*) AS records_total,
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COUNT(*) FILTER (WHERE "some_column" IS NOT NULL) AS records_filtered
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FROM models
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*Andrey Novikov*
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* Two change tracking methods are added for `belongs_to` associations.
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The `association_changed?` method (assuming an association named `:association`) returns true
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@ -7,6 +7,7 @@
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require "arel/expressions"
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require "arel/predications"
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require "arel/filter_predications"
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require "arel/window_predications"
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require "arel/math"
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require "arel/alias_predication"
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9
activerecord/lib/arel/filter_predications.rb
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9
activerecord/lib/arel/filter_predications.rb
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# frozen_string_literal: true
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module Arel
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module FilterPredications
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def filter(expr)
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Nodes::Filter.new(self, expr)
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end
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end
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end
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@ -28,6 +28,7 @@
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# binary
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require "arel/nodes/binary"
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require "arel/nodes/equality"
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require "arel/nodes/filter"
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require "arel/nodes/in"
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require "arel/nodes/join_source"
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require "arel/nodes/delete_statement"
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10
activerecord/lib/arel/nodes/filter.rb
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10
activerecord/lib/arel/nodes/filter.rb
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# frozen_string_literal: true
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module Arel
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module Nodes
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class Filter < Binary
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include Arel::WindowPredications
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include Arel::AliasPredication
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end
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end
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end
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@ -4,6 +4,7 @@ module Arel # :nodoc: all
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module Nodes
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class Function < Arel::Nodes::NodeExpression
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include Arel::WindowPredications
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include Arel::FilterPredications
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attr_accessor :expressions, :alias, :distinct
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def initialize(expr, aliaz = nil)
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@ -245,6 +245,13 @@ def visit_Arel_Nodes_Window(o, collector)
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collector << ")"
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end
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def visit_Arel_Nodes_Filter(o, collector)
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visit o.left, collector
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collector << " FILTER (WHERE "
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visit o.right, collector
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collector << ")"
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end
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def visit_Arel_Nodes_Rows(o, collector)
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if o.expr
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collector << "ROWS "
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37
activerecord/test/cases/arel/nodes/filter_test.rb
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37
activerecord/test/cases/arel/nodes/filter_test.rb
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# frozen_string_literal: true
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require_relative "../helper"
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module Arel
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module Nodes
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class ::FilterTest < Arel::Spec
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describe "Filter" do
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it "should add filter to expression" do
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table = Arel::Table.new :users
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_(table[:id].count.filter(table[:income].gteq(40_000)).to_sql).must_be_like %{
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COUNT("users"."id") FILTER (WHERE "users"."income" >= 40000)
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}
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end
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describe "as" do
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it "should alias the expression" do
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table = Arel::Table.new :users
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_(table[:id].count.filter(table[:income].gteq(40_000)).as("rich_users_count").to_sql).must_be_like %{
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COUNT("users"."id") FILTER (WHERE "users"."income" >= 40000) AS rich_users_count
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}
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end
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end
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describe "over" do
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it "should reference the window definition by name" do
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table = Arel::Table.new :users
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window = Arel::Nodes::Window.new.partition(table[:year])
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_(table[:id].count.filter(table[:income].gteq(40_000)).over(window).to_sql).must_be_like %{
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COUNT("users"."id") FILTER (WHERE "users"."income" >= 40000) OVER (PARTITION BY "users"."year")
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}
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end
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end
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end
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end
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end
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end
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