The body document (UrlPage)
Every DomUI page extends UrlPage, and a UrlPage is the <body> of the
rendered document. It is an ordinary NodeContainer - a Div subclass, in fact
- so everything true of a node is true of it, and this page is only about the things that are true of it alone.
The title in the browser
setTitle("Album - " + album.getTitle()); // the browser's title bar
setPageTitle("Album"); // the title bar on the page
On every other node, title is the html title attribute - the tooltip. On
a UrlPage it is the <title> element of the document instead, because the
page is the body and the head is rendered from it.
pageTitle is a different property with a confusingly similar name: it is the
page's name as AppPageTitleBar and
the breadcrumb show it, and it never reaches the head.
A page that sets no title gets one from
DomApplication.getDefaultPageTitle(body), which is
"DomUI Application - " + the class's simple name unless the application
overrides it.
Lifecycle hooks
createContent() builds the page and is called again after every
forceRebuild(). Around it, UrlPage adds hooks that only a page has:
| Method | When it runs |
|---|---|
onReload() |
the page is being reloaded - a root page only |
onDestroy() |
the page is being thrown away, by navigation or by the conversation ending |
onAfterRequest() |
at the end of every request that touched this page |
afterCreateContent() |
after createContent() has run, for a base class that has to act on the finished tree |
onForceRebuild() |
the tree is about to be discarded and rebuilt |
onShelve() and onUnshelve() come from NodeContainer and fire when the page
is put aside for another page and brought back;
state management is where that story is told.
The database context of the page
QDataContext dc = getSharedContext();
A page has a shared QDataContext: created when first asked for, held by the
page's conversation, released when that conversation ends. Every component on
the page that asks gets the same one, which is what makes an entity loaded in
one part of the page the same object as in another.
getSharedContext(key) gives a second, independent context under a name of your
own, for work that must not sit in the same transaction.
resetAllSharedContexts() throws them all away. forceReloadData() does that,
re-injects the page's URL parameters and rebuilds - the way to make a page
re-read everything it shows.
lc() returns the ILogicContext for the page's shared context - the entry
point to the logic classes, when an application uses them.
Odds and ends
redirectIn(url, milliseconds)schedules a browser redirect, for a page that shows something and then moves on.closeWindow()closes the browser window the page is in.postbox()is the page'sAsyncMessageLink: how work on another thread hands results back to the page (see asynchronous work).setThemeVariant()puts this page on a variant of the current theme.