diff options
Diffstat (limited to 'config')
| -rw-r--r-- | config/initializers/postgresql_cte.rb | 132 |
1 files changed, 132 insertions, 0 deletions
diff --git a/config/initializers/postgresql_cte.rb b/config/initializers/postgresql_cte.rb new file mode 100644 index 00000000000..7f0df8949db --- /dev/null +++ b/config/initializers/postgresql_cte.rb @@ -0,0 +1,132 @@ +# Adds support for WITH statements when using PostgreSQL. The code here is taken +# from https://github.com/shmay/ctes_in_my_pg which at the time of writing has +# not been pushed to RubyGems. The license of this repository is as follows: +# +# The MIT License (MIT) +# +# Copyright (c) 2012 Dan McClain +# +# Permission is hereby granted, free of charge, to any person obtaining a copy +# of this software and associated documentation files (the "Software"), to deal +# in the Software without restriction, including without limitation the rights +# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +# copies of the Software, and to permit persons to whom the Software is +# furnished to do so, subject to the following conditions: +# +# The above copyright notice and this permission notice shall be included in +# all copies or substantial portions of the Software. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +# THE SOFTWARE. + +module ActiveRecord + class Relation + class Merger # :nodoc: + def normal_values + NORMAL_VALUES + [:with] + end + end + end +end + +module ActiveRecord::Querying + delegate :with, to: :all +end + +module ActiveRecord + class Relation + # WithChain objects act as placeholder for queries in which #with does not have any parameter. + # In this case, #with must be chained with #recursive to return a new relation. + class WithChain + def initialize(scope) + @scope = scope + end + + # Returns a new relation expressing WITH RECURSIVE + def recursive(*args) + @scope.with_values += args + @scope.recursive_value = true + @scope + end + end + + def with_values + @values[:with] || [] + end + + def with_values=(values) + raise ImmutableRelation if @loaded + @values[:with] = values + end + + def recursive_value=(value) + raise ImmutableRelation if @loaded + @values[:recursive] = value + end + + def recursive_value + @values[:recursive] + end + + def with(opts = :chain, *rest) + if opts == :chain + WithChain.new(spawn) + elsif opts.blank? + self + else + spawn.with!(opts, *rest) + end + end + + def with!(opts = :chain, *rest) # :nodoc: + if opts == :chain + WithChain.new(self) + else + self.with_values += [opts] + rest + self + end + end + + def build_arel + arel = super() + + build_with(arel) if @values[:with] + + arel + end + + def build_with(arel) + with_statements = with_values.flat_map do |with_value| + case with_value + when String + with_value + when Hash + with_value.map do |name, expression| + case expression + when String + select = Arel::Nodes::SqlLiteral.new "(#{expression})" + when ActiveRecord::Relation, Arel::SelectManager + select = Arel::Nodes::SqlLiteral.new "(#{expression.to_sql})" + end + Arel::Nodes::As.new Arel::Nodes::SqlLiteral.new("\"#{name}\""), select + end + when Arel::Nodes::As + with_value + end + end + + unless with_statements.empty? + if recursive_value + arel.with :recursive, with_statements + else + arel.with with_statements + end + end + end + end +end |