As previously mentioned in the previous chapter, methods defined in Handlers are Business Logic. You are supposed to write your program in there.

The following methods are predefined in Handlers. Their names are starting with __ as prefix to avoid duplicate name.

The Callable Methods In Business Logic

The above methods are defined as instance methods and its accessibilities are protected.

__root

It returns a string value as the application root.

__assign(list)

Assigns specific variables into tempaltes.

__set_content_type(type)

Sets Content-Type header by a specific type. The configuration of content directive in route.yml will be overwritten after calling this method.

e.g.

class ExampleHandler < BaseHandler
    def index
        # The response header 'Content-Type:application/json' will be set
        __set_content_type :json
    end
end

__set_header(field, value)

Sets a specific response header. If the specified field name has already been set this method will overwrite it to the new value.

e.g.

class ExampleHandler < BaseHandler
    def index
        # The response header 'X-XSS-Protection:1;mode=block' will be set
        __set_header 'X-XSS-Protection', '1;mode=block'
    end
end

__set_headers(headers)

Sets specific response headers. The difference in __set_header is __set_headers can set any number of headers at the same time.

If the specified field name has already been set this method will overwrite it to the new value.

e.g.

class ExampleHandler < BaseHandler
    def index
        # The response headers 'Foo:1', 'Bar:2' will be set
        headers = {
            :Foo => 1,
            :Bar => 2
        }
        __set_headers headers
    end
end

__add_header(field, value, delimiter = ‘; ‘)

Adds a specific value to the existing header with a specific delimiter.

The specific header will be set anew if no header matched the specific field.

e.g.

class ExampleHandler < BaseHandler
    def index
        __set_header :Foo, 'Existing value'
        __add_header :Foo, 'Add a new value'
        #=> Response header 'Foo:Existing value; Add a new value' will be set
    end
end

__set_code(code)

Sets HTTP response status code.

e.g.

class ExampleHandler < BaseHandler
    def index
        # 'Status Code:401 Unauthorized' will be set
        __set_code 401
    end
end

__set_body(body)

Sets specific data to HTTP message body for response.

e.g.

class ExampleHandler < BaseHandler
    def index
        require 'json'
        response = {
            'foo' => 1,
            'bar' => 2
        }
        __set_content_type :json
        __set_body response.to_json
    end
end

The reponse body must be {"foo":1,"bar":2}.

__set_json_body(body)

Sets specific data as json to HTTP message body for response. The parameter body requires that it must be set as hash type.

The given body will be converted to json format string by JSON.pretty_generate method of json module in the standard library.

e.g.

class ExampleHandler < BaseHandler
    def index
        response = {
            'foo' => 1,
            'bar' => 2
        }
        __set_content_type :json
        __set_json_body response
    end
end

The reponse body must be {"foo":1,"bar":2}.

__add_body(body)

Adds specific data to the existing HTTP message body.

The specific data will be set anew to HTTP message body if no HTTP message has not been set.

e.g.

class ExampleHandler < BaseHandler
    def index
        __set_body 'Foo'
        __add_body 'Boo'
    end
end

The reponse body must be FooBoo.

__env_get(field = nil)

Returns a value of Rack environment from a specific field name.

e.g.

class ExampleHandler < BaseHandler
    def index
        # Get The User Agent
        ua = __env_get :HTTP_USER_AGENT
    end
end

This method is the alias for the class method Nekonote::Env.get.

__env_keys

Returns the list of field names for __env_get. It returns array.

This method is the alias for the class method Nekonote::Env.keys.

__setting_get(*fields)

Returns values from user configuration files by some specific field names. The return values depend on your user configuration files and the given values.

User configuration files are explained this chapter.

preference/your_environment/example.yml

path:
    foo: /path/to/foo
    bar: /path/to/bar

handler/foo.rb

class ExampleHandler < BaseHandler
    def index
        # It returns array {"foo"=>"/path/to/foo", "bar"=>"/path/to/bar"}
        path_list = __setting_get :path

        # It returns string /path/to/bar
        path_bar = __setting_get :path, :bar
    end
end

__setting_keys

Returns the list of top level field names from user setting files for __setting_get. It returns array.

__set_template(template)

Sets template. It overwrites configurations in route.yml.

__set_layout(layout)

Sets layout. It overwrites configurations in route.yml.

__redirect(dest, code=302)

Issues HTTP redirect.

When you would like to redirect in the middle of program, you must use return as the following example.

class ExampleHandler < BaseHandler
    def index
        # your program here

        return __redirect 'http://example.com'

        logwrite 'program after redirect'
    end
end

The above example redirects the request to the destination consisting of URI scheme and FQDN.

If you would like to redirect another page in the same FQDN, just giving the path to the page as the following example.

class ExampleHandler < BaseHandler
    def index
        __redirect 'path/to/some/page'
    end
end

The above example redirects the request to /path/to/some/page in the same URI scheme and FQDN.

Predefined Properties In Handlers

The following properties are predefined in Handler classes. You may use them when you need it.

Predefined Public Methods In Handlers

These methods are special. You are not supposed to overwrite them.