Define the menu tree
When you are defining a page, there are 4 fields related to menu.
Nav Parent：The parent page on navigation tree.
Show In Menu: Appear on navigation tree or not
Navigation Text: Link Text, the page object also has a LinkText Property which will get the page name when navigation text is not available.
Navigation Order: Sort order
To make a page appear in the menu tree, "Show In Menu" must be checked.
Query the menu
There are 4 methods in PageHelper object to query menu tree.
getNavigation: Get sub pages of one cms_page
GetParentNavigation： Get the parent page object of one cms_page.
GetSubNavigations: Get the child list of cms_page object of current cms_page
GetTopNavigations: Get the list of root cms_pages, those page do not have parent page.
Below are some sample codes for building the site navigation.