discourse/lib/migration/column_dropper.rb

65 lines
2.0 KiB
Ruby

require_dependency 'migration/base_dropper'
module Migration
class ColumnDropper < BaseDropper
def self.drop(table:, after_migration:, columns:, delay: nil, on_drop: nil)
validate_table_name(table)
columns.each { |column| validate_column_name(column) }
ColumnDropper.new(table, columns, after_migration, delay, on_drop).delayed_drop
end
def self.mark_readonly(table_name, column_name)
create_readonly_function(table_name, column_name)
ActiveRecord::Base.exec_sql <<~SQL
CREATE TRIGGER #{readonly_trigger_name(table_name, column_name)}
BEFORE INSERT OR UPDATE OF #{column_name}
ON #{table_name}
FOR EACH ROW
WHEN (NEW.#{column_name} IS NOT NULL)
EXECUTE PROCEDURE #{readonly_function_name(table_name, column_name)};
SQL
end
private
def initialize(table, columns, after_migration, delay, on_drop)
super(after_migration, delay, on_drop)
@table = table
@columns = columns
end
def droppable?
builder = SqlBuilder.new(<<~SQL)
SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS
/*where*/
LIMIT 1
SQL
builder.where("table_schema = 'public'")
.where("table_name = :table")
.where("column_name IN (:columns)")
.where(previous_migration_done)
.exec(table: @table,
columns: @columns,
delay: "#{@delay} seconds",
after_migration: @after_migration).to_a.length > 0
end
def execute_drop!
@columns.each do |column|
ActiveRecord::Base.exec_sql <<~SQL
DROP TRIGGER IF EXISTS #{BaseDropper.readonly_trigger_name(@table, column)} ON #{@table};
DROP FUNCTION IF EXISTS #{BaseDropper.readonly_function_name(@table, column)} CASCADE;
SQL
# safe cause it is protected on method entry, can not be passed in params
ActiveRecord::Base.exec_sql("ALTER TABLE #{@table} DROP COLUMN IF EXISTS #{column}")
end
end
end
end