Module: Sequel::Postgres::Comment::DatabaseMethods

Defined in:
lib/sequel/extensions/pg_comment/database_methods.rb

Overview

Support for setting and retrieving comments on all object types in a PostgreSQL database.

Instance Method Summary collapse

Instance Method Details

#apply_alter_table_generator(name, generator) ⇒ Object

:nodoc: Enhanced version to support setting comments on objects created in a block-form alter_table statement.



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 143

def apply_alter_table_generator(name, generator)
	super

	schema, table = schema_and_table(name)
	fqtable = [schema, table].compact.map { |e| literal e.to_sym }.join('.')

	generator.operations.each do |op|
		if op[:comment]
			case op[:op]
			when :add_column
				comment_on(:column, [name, op[:name]], op[:comment])
			when :add_constraint
				case op[:type]
				when :primary_key
					comment_on(:index, "#{name}_pkey".to_sym, op[:comment])
				when :foreign_key, :check
					c_name = op[:name] || "#{name}_#{op[:columns].first}_fkey".to_sym
					comment_on(:constraint, [name, c_name], op[:comment])
				when :unique
					c_name = op[:name] || ([name] + op[:columns] + ["key"]).join("_").to_sym
					comment_on(:index, c_name, op[:comment])
				end
			when :add_index
				c_name = op[:name] || ([name] + op[:columns] + ["index"]).join("_").to_sym
				comment_on(:index, c_name, op[:comment])
			end
		end
	end
end

#comment_for(object) ⇒ String, NilClass

Retrieve the comment for a database object.

Parameters:

  • object (#to_s) —

    The name of the database object to retrieve. For most objects, this should be the literal name of the object. However, for columns on tables and views, the name of the table/view should be a separated from the name of the column by a double underscore (ie __).

Returns:

  • (String, NilClass) —

    The comment on the object, or nil if no comment has been defined for the object.



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 56

def comment_for(object)
	object = object.to_s

	if object.index("__")
		tbl, col = object.split("__", 2)

		(select(Sequel.function(:col_description, :c__oid, :a__attnum).as(:comment)).
		   from(Sequel.as(:pg_class, :c)).
		   join(Sequel.as(:pg_attribute, :a), :c__oid => :a__attrelid).
		   where(:c__relname => tbl).
		   and(:a__attname => col).first || {})[:comment]
	else
		(select(
		   Sequel.function(
		     :obj_description,
		     Sequel.cast(object, :regclass),
		     "pg_class"
		   ).as(:comment)
		 ).first || {})[:comment]
	end
end

#comment_on(type, id, comment) ⇒ Object

Parameters:

  • type (Symbol) —

    The object type you're looking to set the comment on. This is just the PostgreSQL type name, lowercased, with spaces replaced with underscores.

  • id (Symbol, String, Array<Symbol, String>) —

    The identifier of the object that you wish to comment on. For most types of object, this should be the literal name of the object. However, for objects which are "contained" in another object (columns in tables/views, and constraints, triggers, and rules in tables) you must pass the identifier as a two-element array, where the first element is the container table or view, and the second element is the contained object (column, constraint, rule, or trigger).

    In any event, when a Symbol is encountered, it is quoted for safety, and split into a schema and object name pair, if appropriate. If a String is passed, then no escaping or quoting is done. While this is a slight risk, it is necessary to allow you to reference complex object names which can't reasonably be described otherwise (FUNCTION, I'm looking at you).

  • comment (String) —

    The comment you wish to set for the database object.

Raises:

  • (Sequel::Error) —

    if the specified type isn't recognised.

See Also:

  • for details on how the comment string is interpreted.


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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 33

def comment_on(type, id, comment)
	if Sequel::Postgres::Comment::STANDALONE_TYPES.include?(type)
		comment_on_standalone_type(type, id, comment)
	elsif Sequel::Postgres::Comment::CONTAINED_TYPES.include?(type)
		comment_on_contained_type(type, id, comment)
	else
		raise Sequel::Error,
		      "Unknown object type: #{type.inspect}"
	end
end

#create_table(*args) ⇒ Object

An enhanced form of the standard create_table method, which supports setting a comment in the create_table call when the :comment option is provided.

Parameters:

  • [String] (Hash) —

    a customizable set of options

See Also:



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 86

def create_table(*args)
	super

	if args.last.is_a?(Hash) && args.last[:comment]
		comment_on(:table, args.first, args.last[:comment])
	end
end

#create_table_from_generator(name, generator, options) ⇒ Object

:nodoc: Enhanced to support creating comments on columns, after the table itself (and hence all its columns) have been created.



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 98

def create_table_from_generator(name, generator, options)
	generator.columns.each do |col|
		if col[:comment]
			comment_on(:column, [name, col[:name]], col[:comment])
		end
	end

	generator.constraints.each do |c|
		case c[:type]
		when :primary_key
			c_name = c[:name] || "#{name}_pkey".to_sym
			comment_on(:index, c_name, c[:comment])
		when :foreign_key, :check
			if c[:type] == :check && c[:name].nil?
				raise Sequel::Error,
				      "Setting comments on unnamed check constraints is not supported"
			end
			c_name = c[:name] || "#{name}_#{c[:columns].first}_fkey".to_sym
			comment_on(:constraint, [name, c_name], c[:comment])
		when :unique
			c_name = c[:name] || ([name] + c[:columns] + ["key"]).join("_").to_sym
			comment_on(:index, c_name, c[:comment])
		end
	end
end

#create_table_indexes_from_generator(name, generator, options) ⇒ Object

:nodoc: Enhanced to support creating comments on indexes, after the indexes themselves have been created.



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 128

def create_table_indexes_from_generator(name, generator, options)
	super

	generator.indexes.each do |idx|
		if idx[:comment]
			i_name = idx[:name] || ([name] + idx[:columns] + ["index"]).join("_").to_sym
			comment_on(:index, i_name, idx[:comment])
		end
	end
end

#create_view(*args) ⇒ Object

An enhanced form of the standard create_view method, which supports setting a comment in the create_view call when the :comment option is provided.

Parameters:

  • [String] (Hash) —

    a customizable set of options

See Also:



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# File 'lib/sequel/extensions/pg_comment/database_methods.rb', line 181

def create_view(*args)
	super

	if args.last.is_a?(Hash) && args.last[:comment]
		comment_on(:view, args.first, args.last[:comment])
	end
end