Module: DynamicMigrations::ActiveRecord::Migrators::Function

Included in:
DynamicMigrations::ActiveRecord::Migrators
Defined in:
lib/dynamic_migrations/active_record/migrators/function.rb

Defined Under Namespace

Classes: FunctionDoesNotExistError, MissingFunctionBlockError

Instance Method Summary collapse

Instance Method Details

#create_function(function_name, comment: nil, &block) ⇒ Object

create a postgres function



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# File 'lib/dynamic_migrations/active_record/migrators/function.rb', line 12

def create_function function_name, comment: nil, &block
  unless block
    raise MissingFunctionBlockError, "create_function requires a block"
  end
  # todo - remove this once steep/rbs can better handle blocks
  unless block.is_a? NilClass
    fn_sql = block.call.strip
  end

  # schema_name was not provided to this method, it comes from the migration class
  execute <<~SQL
    CREATE FUNCTION #{schema_name}.#{function_name}() returns trigger language plpgsql AS
    $$#{fn_sql}$$;
  SQL

  if comment.is_a? String
    set_function_comment function_name, comment
  end
end

#drop_function(function_name) ⇒ Object

remove a function from the schema



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# File 'lib/dynamic_migrations/active_record/migrators/function.rb', line 72

def drop_function function_name
  execute <<~SQL
    DROP FUNCTION #{schema_name}.#{function_name}();
  SQL
end

#remove_function_comment(function_name) ⇒ Object

remove the comment from a function



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# File 'lib/dynamic_migrations/active_record/migrators/function.rb', line 86

def remove_function_comment function_name
  execute <<~SQL
    COMMENT ON FUNCTION #{schema_name}.#{function_name} IS null;
  SQL
end

#set_function_comment(function_name, comment) ⇒ Object

add a comment to a function



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# File 'lib/dynamic_migrations/active_record/migrators/function.rb', line 79

def set_function_comment function_name, comment
  execute <<~SQL
    COMMENT ON FUNCTION #{schema_name}.#{function_name} IS #{quote comment};
  SQL
end

#update_function(function_name, comment: nil, &block) ⇒ Object

update a postgres function



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# File 'lib/dynamic_migrations/active_record/migrators/function.rb', line 33

def update_function function_name, comment: nil, &block
  unless block
    raise MissingFunctionBlockError, "create_function requires a block"
  end
  # todo - remove this once steep/rbs can better handle blocks
  unless block.is_a? NilClass
    fn_sql = block.call.strip
  end

  # schema_name was not provided to this method, it comes from the migration class
  # assert it already exists
  exists_result = execute <<~SQL
    SELECT TRUE as exists
    FROM pg_proc p
    INNER JOIN pg_namespace p_n
      ON p_n.oid = p.pronamespace
    WHERE
      p.proname = #{function_name}
      AND p_n.nspname = #{schema_name}
      -- arguments (defaulting to none for now)
      AND pg_get_function_identity_arguments(p.oid) = ''
  SQL

  unless exists_result.to_a.first["exists"]
    raise FunctionDoesNotExistError, "Can not update Function. Function #{schema_name}.#{function_name} does not exist."
  end

  # create or replace will update the function
  execute <<~SQL
    CREATE OR REPLACE FUNCTION #{schema_name}.#{function_name}() returns trigger language plpgsql AS
    $$#{fn_sql}$$;
  SQL

  if comment.is_a? String
    set_function_comment function_name, comment
  end
end