S3Navigation

S3Navigation is an S3 module providing a generic framework for the implementation of navigation elements in the web UI.

S3NavigationItem

S3NavigationItem is a base class for the implementation of navigation items, and provides the common logic for all types of navigation items as well as an API for renderers.

Navigation items are UI elements to navigate the application, and can appear as menus, breadcrumb rows, tab rows, and various other types of links. They all have in common that they are linked to request URLs and usually get activated by clicking them.

Subclassing S3NavigationItem

The S3NavigationItem class is not meant to be used directly for the implementation of navigation items. Instead, it should be subclassed for each type of navigation items the user interface needs. Subclasses of S3NavigationItem are supposed to implement the layout of the respective item type, and are therefore referred to as Layouts.

To implement a Layout, create a new subclass of S3NavigationItem and implement a (static) method layout:

class MyMenuLayout(S3NavigationItem):

    @staticmethod
    def layout(item):
        # Layout implementation goes here

The layout method takes an instance of the layout class as parameter, and returns an instance of a web2py HTML helper class (DIV or a subclass of it). This HTML instance is what eventually gets written into the view.

The layout method can make use of the renderer API to retrieve the item's attributes and flags.

Defining Navigation Items

Once you have implemented the Layout, you can create instances of it to define the particular navigation elements. The elements can be nested using the call-method:

my_menu = MyMenuLayout("Home")(
             MyMenuLayout("First Item"),
             MyMenuLayout("Second Item"),
             MyMenuLayout("Submenu")(
                 MyMenuLayout("First SubmenuItem"),
                 MyMenuLayout("Second SubmenuItem")
             )
           )

Each particular item can receive any number of keyword parameters. The following keyword parameters are used by the base-class:

Keyword	Type	Meaning	Comments
label	string	The label for the item (if any)	always the first parameter, so the keyword can be omitted; labels which are not already T instances (localized strings) will automatically be rendered with T unless you set translate=False
r	Request	The request object	if passed, then the item inherits a, c, and f from this request, i.e. the item will always match this request
a	string	The application name in the target URL	inherited from parent item
c	string	The controller name in the target URL	inherited from parent item
f	string	The function name in the target URL	inherited from parent item
args	list of strings, or string	the arguments in the target URL	if passed as single string, the arguments must be separated by slashes
vars	dict of strings	the query variables in the target URL
extension	string	the URL extension (data format extension) in the target URL	defaults to None
p	string	the permission required to access this item	defaults to m
m	string	the URL method for the request	defaults to "", will be appended to args if not the last arg
t	string	the name of the table the permission is required for	defaults to <c>_<f>
tags	list of strings	a list of tags for this item	tags can later be used to address this item in the menu tree, e.g. to update flags
parent	the parent item	set the parent item explicitly	special purpose, defaults to None and should be left at that
translate	boolean	False will prevent automatic localization of the item label
layout	function	use this function to render this item instead of the layout of the class
check	boolean, function or mixed list of these types	conditions to check before rendering	functions will be called with the item as parameter and are expected to return a boolean
restrict	list of role IDs or UIDs	restrict access to this item to these roles
link	boolean	whether to link this item to the specified target URL or not	defaults to True = all items get linked
mandatory	boolean	override active check - item is always active	not implemented yet

All other keyword parameters will be stored in the item instance and passed on to the layout method - keywords starting with an "_" underscore will be stored in item.attributes, all other keywords in item.options (it is up to the layout method to deal with those then).

Rendering Navigation Items

To render a navigation element, just put it into the view like:

{{=my_menu}}

This will call the layout method of the element, provided whenever the element is active (i.e. relevant for the current request).

Implementing Layouts

Eden Standard Menus

Customizing Menus