diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/merger.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/merger.rb | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/relation/merger.rb b/activerecord/lib/active_record/relation/merger.rb new file mode 100644 index 0000000000..4de7465128 --- /dev/null +++ b/activerecord/lib/active_record/relation/merger.rb @@ -0,0 +1,189 @@ +# frozen_string_literal: true + +require "active_support/core_ext/hash/keys" + +module ActiveRecord + class Relation + class HashMerger # :nodoc: + attr_reader :relation, :hash + + def initialize(relation, hash) + hash.assert_valid_keys(*Relation::VALUE_METHODS) + + @relation = relation + @hash = hash + end + + def merge #:nodoc: + Merger.new(relation, other).merge + end + + # Applying values to a relation has some side effects. E.g. + # interpolation might take place for where values. So we should + # build a relation to merge in rather than directly merging + # the values. + def other + other = Relation.create( + relation.klass, + table: relation.table, + predicate_builder: relation.predicate_builder + ) + hash.each { |k, v| + if k == :joins + if Hash === v + other.joins!(v) + else + other.joins!(*v) + end + elsif k == :select + other._select!(v) + else + other.send("#{k}!", v) + end + } + other + end + end + + class Merger # :nodoc: + attr_reader :relation, :values, :other + + def initialize(relation, other) + @relation = relation + @values = other.values + @other = other + end + + NORMAL_VALUES = Relation::VALUE_METHODS - + Relation::CLAUSE_METHODS - + [:includes, :preload, :joins, :left_outer_joins, :order, :reverse_order, :lock, :create_with, :reordering] # :nodoc: + + def normal_values + NORMAL_VALUES + end + + def merge + normal_values.each do |name| + value = values[name] + # The unless clause is here mostly for performance reasons (since the `send` call might be moderately + # expensive), most of the time the value is going to be `nil` or `.blank?`, the only catch is that + # `false.blank?` returns `true`, so there needs to be an extra check so that explicit `false` values + # don't fall through the cracks. + unless value.nil? || (value.blank? && false != value) + if name == :select + relation._select!(*value) + else + relation.send("#{name}!", *value) + end + end + end + + merge_multi_values + merge_single_values + merge_clauses + merge_preloads + merge_joins + merge_outer_joins + + relation + end + + private + + def merge_preloads + return if other.preload_values.empty? && other.includes_values.empty? + + if other.klass == relation.klass + relation.preload!(*other.preload_values) unless other.preload_values.empty? + relation.includes!(other.includes_values) unless other.includes_values.empty? + else + reflection = relation.klass.reflect_on_all_associations.find do |r| + r.class_name == other.klass.name + end || return + + unless other.preload_values.empty? + relation.preload! reflection.name => other.preload_values + end + + unless other.includes_values.empty? + relation.includes! reflection.name => other.includes_values + end + end + end + + def merge_joins + return if other.joins_values.blank? + + if other.klass == relation.klass + relation.joins!(*other.joins_values) + else + joins_dependency = other.joins_values.map do |join| + case join + when Hash, Symbol, Array + other.send(:construct_join_dependency, join) + else + join + end + end + + relation.joins!(*joins_dependency) + end + end + + def merge_outer_joins + return if other.left_outer_joins_values.blank? + + if other.klass == relation.klass + relation.left_outer_joins!(*other.left_outer_joins_values) + else + joins_dependency = other.left_outer_joins_values.map do |join| + case join + when Hash, Symbol, Array + other.send(:construct_join_dependency, join) + else + join + end + end + + relation.left_outer_joins!(*joins_dependency) + end + end + + def merge_multi_values + if other.reordering_value + # override any order specified in the original relation + relation.reorder!(*other.order_values) + elsif other.order_values.any? + # merge in order_values from relation + relation.order!(*other.order_values) + end + + extensions = other.extensions - relation.extensions + relation.extending!(*extensions) if extensions.any? + end + + def merge_single_values + relation.lock_value ||= other.lock_value if other.lock_value + + unless other.create_with_value.blank? + relation.create_with_value = (relation.create_with_value || {}).merge(other.create_with_value) + end + end + + def merge_clauses + relation.from_clause = other.from_clause if replace_from_clause? + + where_clause = relation.where_clause.merge(other.where_clause) + relation.where_clause = where_clause unless where_clause.empty? + + having_clause = relation.having_clause.merge(other.having_clause) + relation.having_clause = having_clause unless having_clause.empty? + end + + def replace_from_clause? + relation.from_clause.empty? && !other.from_clause.empty? && + relation.klass.base_class == other.klass.base_class + end + end + end +end |