Module: DynamicMigrations::Postgres::Generator::Trigger

Included in:
DynamicMigrations::Postgres::Generator
Defined in:
lib/dynamic_migrations/postgres/generator/trigger.rb

Defined Under Namespace

Classes: TemplateAlreadyExistsError, UnexpectedTemplateError

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.add_template(name, template_class) ⇒ Object

install a template into the migration generator, this can be used from outside this library to clean up common migrations (replace common migrations with syntatic sugar)

Raises:



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 21

def self.add_template name, template_class
  @templates ||= {}
  raise TemplateAlreadyExistsError, name if @templates.key?(name)
  @templates[name] = template_class
end

.has_template?(template_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 15

def self.has_template? template_name
  @templates&.key?(template_name) || false
end

.template(template_name) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 11

def self.template template_name
  @templates && @templates[template_name]
end

Instance Method Details

#add_trigger(trigger, code_comment = nil) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 27

def add_trigger trigger, code_comment = nil
  # if we have a corresponding template, then use it
  if trigger.template
    unless (template_class = Trigger.template(trigger.template))
      raise UnexpectedTemplateError, "Unrecognised template #{trigger.template}"
    end

    arguments = template_class.new(trigger, code_comment).fragment_arguments

    # if the template class returns nil, then we skip the creation of this migration
    # this is common for triggers where the template is respinsible for setting up
    # multiple triggers (a mix of on update/insert and before/after etc.)
    unless arguments.nil?
      # we only provide a dependent function if the function has more than one trigger
      # or is in a different schema, otherwise it is added to the same migration as this
      # trigger and we don't need to worry about dependencies
      if trigger.function && (trigger.function.triggers.count > 1 || trigger.table.schema != trigger.function.schema)
        add_fragment(dependent_function: trigger.function, **arguments)
      else
        add_fragment(**arguments)
      end
    end

  # no template, process this as a default trigger (takes all options)
  else
    options = {
      name: ":#{trigger.name}"
    }

    # if the trigger is a row trigger and the action timing is before or after
    # then we can use some syntactic sugar to make the migration look nicer
    # we use method names like before_insert, after_update, etc. and drop the
    # unnessessary options
    if trigger.action_orientation == :row && [:before, :after].include?(trigger.action_timing)
      method_name = "#{trigger.action_timing}_#{trigger.event_manipulation}"
    else
      method_name = "add_trigger"
      options[:action_timing] = ":#{trigger.action_timing}"
      options[:event_manipulation] = ":#{trigger.event_manipulation}"
      options[:action_orientation] = ":#{trigger.action_orientation}"
    end

    # added here because we want the timing and manipulation to visually appear first
    options[:function_schema_name] = ":#{trigger.function.schema.name}"
    options[:function_name] = ":#{trigger.function.name}"

    unless trigger.action_condition.nil?
      options[:action_condition] = "\"#{trigger.action_condition}\""
    end

    unless trigger.parameters.empty?
      options[:parameters] = "[\"#{trigger.parameters.join('", "')}\"]"
    end

    unless trigger.action_reference_old_table.nil?
      options[:action_reference_old_table] = ":#{trigger.action_reference_old_table}"
    end

    unless trigger.action_reference_new_table.nil?
      options[:action_reference_new_table] = ":#{trigger.action_reference_new_table}"
    end

    unless trigger.description.nil?
      options[:comment] = <<~RUBY
        <<~COMMENT
          #{indent trigger.description}
        COMMENT
      RUBY
    end

    options_syntax = options.map { |k, v| "#{k}: #{v}" }.join(", ")

    # we only provide a dependent function if the function has more than one trigger
    # or is in a different schema, otherwise it is added to the same migration as this
    # trigger and we don't need to worry about dependencies
    dependent_function = nil
    # trigger.function will be nil if the trigger is not an function
    if trigger.function && (trigger.function.triggers.count > 1 || trigger.table.schema != trigger.function.schema)
      dependent_function = trigger.function
    end

    add_fragment schema: trigger.table.schema,
      table: trigger.table,
      migration_method: :add_trigger,
      object: trigger,
      code_comment: code_comment,
      dependent_function: dependent_function,
      migration: <<~RUBY
        #{method_name} :#{trigger.table.name}, #{options_syntax}
      RUBY
  end
end

#recreate_trigger(original_trigger, updated_trigger) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 131

def recreate_trigger original_trigger, updated_trigger
  fragments = []
  # remove the original trigger
  fragments << remove_trigger(original_trigger, <<~CODE_COMMENT)
    Removing original trigger because it has changed (it is recreated below)
    Changes:
      #{indent original_trigger.differences_descriptions(updated_trigger).join("\n")}
  CODE_COMMENT

  # recrete the trigger with the new options
  recreation_fragment = add_trigger updated_trigger, <<~CODE_COMMENT
    Recreating this trigger
  CODE_COMMENT
  fragments << recreation_fragment unless recreation_fragment.nil?

  # return the new fragments (the main reason to return them here is for the specs)
  fragments
end

#remove_trigger(trigger, code_comment = nil) ⇒ Object 



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 120

def remove_trigger trigger, code_comment = nil
  add_fragment schema: trigger.table.schema,
    table: trigger.table,
    migration_method: :remove_trigger,
    object: trigger,
    code_comment: code_comment,
    migration: <<~RUBY
      remove_trigger :#{trigger.table.name}, :#{trigger.name}
    RUBY
end

#remove_trigger_comment(trigger, code_comment = nil) ⇒ Object

remove the comment from a trigger



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 171

def remove_trigger_comment trigger, code_comment = nil
  add_fragment schema: trigger.table.schema,
    table: trigger.table,
    migration_method: :remove_trigger_comment,
    object: trigger,
    code_comment: code_comment,
    migration: <<~RUBY
      remove_trigger_comment :#{trigger.table.name}, :#{trigger.name}
    RUBY
end

#set_trigger_comment(trigger, code_comment = nil) ⇒ Object

add a comment to a trigger



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# File 'lib/dynamic_migrations/postgres/generator/trigger.rb', line 151

def set_trigger_comment trigger, code_comment = nil
  description = trigger.description

  if description.nil?
    raise MissingDescriptionError, "Missing required description for trigger `#{trigger.name}` on table `#{trigger.table.schema.name}.#{trigger.table.name}`"
  end

  add_fragment schema: trigger.table.schema,
    table: trigger.table,
    migration_method: :set_trigger_comment,
    object: trigger,
    code_comment: code_comment,
    migration: <<~RUBY
      set_trigger_comment :#{trigger.table.name}, :#{trigger.name}, <<~COMMENT
        #{indent description}
      COMMENT
    RUBY
end