Class: Migration::SafeMigrate

Inherits:
Object
  • Object
show all
Defined in:
lib/migration/safe_migrate.rb

Defined Under Namespace

Modules: NiceErrors, SafeMigration

Class Method Summary collapse

Class Method Details

.disable! ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 95

def self.disable!
  return if !PG::Connection.method_defined?(:exec_migrator_unpatched)
  return if ENV["RAILS_ENV"] == "production"

  PG::Connection.class_eval do
    alias_method :exec, :exec_migrator_unpatched
    alias_method :async_exec, :async_exec_migrator_unpatched

    remove_method :exec_migrator_unpatched
    remove_method :async_exec_migrator_unpatched
  end
end

.earliest_post_deploy_version ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 152

def self.earliest_post_deploy_version
  @@earliest_post_deploy_version ||=
    begin
      first_file = Dir.glob("#{Discourse::DB_POST_MIGRATE_PATH}/*.rb").sort.first
      file_name = File.basename(first_file, ".rb")
      file_name.first(14).to_i
    end
end

.enable! ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 75

def self.enable!
  return if PG::Connection.method_defined?(:exec_migrator_unpatched)
  return if ENV["RAILS_ENV"] == "production"

  PG::Connection.class_eval do
    alias_method :exec_migrator_unpatched, :exec
    alias_method :async_exec_migrator_unpatched, :async_exec

    def exec(*args, &blk)
      Migration::SafeMigrate.protect!(args[0])
      exec_migrator_unpatched(*args, &blk)
    end

    def async_exec(*args, &blk)
      Migration::SafeMigrate.protect!(args[0])
      async_exec_migrator_unpatched(*args, &blk)
    end
  end
end

.patch_active_record! ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 108

def self.patch_active_record!
  return if ENV["RAILS_ENV"] == "production"

  ActiveSupport.on_load(:active_record) { ActiveRecord::Migration.prepend(SafeMigration) }

  if defined?(ActiveRecord::Tasks::DatabaseTasks)
    ActiveRecord::Tasks::DatabaseTasks.singleton_class.prepend(NiceErrors)
  end
end

.post_migration_path ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 71

def self.post_migration_path
  Discourse::DB_POST_MIGRATE_PATH
end

.protect!(sql) ⇒ Object 



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# File 'lib/migration/safe_migrate.rb', line 118

def self.protect!(sql)
  if sql =~ /\A\s*(?:drop\s+table|alter\s+table.*rename\s+to)\s+/i
    $stdout.puts("", <<~TEXT)
      WARNING
      -------------------------------------------------------------------------------------
      An attempt was made to drop or rename a table in a migration
      SQL used was: '#{sql}'
      Please generate a post deployment migration using `rails g post_migration` to drop
      or rename the table.

      This protection is in place to protect us against dropping tables that are currently
      in use by live applications.
    TEXT
    raise Discourse::InvalidMigration, "Attempt was made to drop a table"
  elsif sql =~ /\A\s*alter\s+table.*(?:rename|drop(?!\s+not\s+null))\s+/i
    $stdout.puts("", <<~TEXT)
      WARNING
      -------------------------------------------------------------------------------------
      An attempt was made to drop or rename a column in a migration
      SQL used was: '#{sql}'

      Please generate a post deployment migration using `rails g post_migration` to drop
      or rename columns.

      Note, to minimize disruption use self.ignored_columns = ["column name"] on your
      ActiveRecord model, this can be removed 6 months or so later.

      This protection is in place to protect us against dropping columns that are currently
      in use by live applications.
    TEXT
    raise Discourse::InvalidMigration, "Attempt was made to rename or delete column"
  end
end