The initial problem solved by this commit is that it was possible to get
into a situation where a mounting/rendering was started, then the component was
updated, but then another mounting operation begins, and it tries to
reuse the previous rendering operation, which is no longer uptodate.
The underlying issue is that Owl did not track properly the various
internal state change of a component. These issue should be solved by
the introduction of the status enum, which currently tracks 6 possible
states:
- CREATED
- WILLSTARTED
- RENDERED
- MOUNTED
- UNMOUNTED
- DESTROYED
This status number replaces the isMounted and isDestroyed boolean flags.
It has the advantage of making sure that the component is in a
consistent state (it is no longer possible to be destroyed and mounted,
for example)
Another advantage is that it gives us an easy way to track the fact that
a component has been rendered, but is not in the DOM. This is a subtle
situation where some various events can happen, and we need to be able
to react to that case.
Note that there is a change of behaviour: if a component is mounted in a
specific target, then before the mounting is complete, the component is
mounted in another target, we no longer reject the first mounting
operation.
This commit makes sure that Owl does not crash when a component is
created, then updated (for example, with a (observed) state change), and
then, some moment later, mounted.
The initial render is not useful, because it is not linked to a mounting
action anyway. And it caused issues such as a crash when Owl tried to
patch it to a non existing target
This commit tries to improve the interactions involving unmounted
components, or components mounted in an htmelement which is detached
from the main DOM, and rendering actions.
The main example is mounting a component in detached div, to prepare all
children. If we just mount the component, it will work as expected: the
full component tree is rendered in memory, and ready to be really
mounted at the desired target.
However, if before doing that, we update the component and call render
on it (for example, with a change in an observed state), then this
rendering will be ignored, and therefore, the full subcomponent tree is
not uptodate.
This commit will also solve another issue in the compatibility layer in
odoo: in the form renderer, we mount components with the adapter in a
div, which is not yet attached to the DOM. We then manually call the
mounted hook when on_attach_callback is called. This means that before
this commit, any change to the components between the initial rendering
and the call to mounted will be ignored.
As a bonus, this commit has the effect of bringing closer the semantics
of render and mount operations, which is certainly good.
closes#823
Components can implement shouldUpdate to return false. In that case,
renderings coming from above should be ignored.
However, if the component was unmounted and is remounted, we actually
need to force a rerendering in that case, so it is mounted, otherwise
the subcomponent is left in unmounted state, which means that rendering
are ignored.
closes#800
Owl has to manage a lot of interesting situations. One of them is when
a rendering is initiated, which creates a sub component, but then
another rendering starts, which invalidate the previous one, and will
create another sub component. Since the first sub component was not
ever in the DOM, we cannot rely on the vdom patching process to remove
it, so we have to do it manually.
Sadly, this is actually a very tricky situation, since there are other
subtle situations where the code that remove an unmounted widget could
be executed, in particular when the parent component is unmounted, then
remounted, then modified to trigger yet another rendering.
In this commit, we handle this case more carefully by making sure that
the destroyed subcomponent properly configures its pvnode so the patch
process happens as expected.
joint work with the framework team, and in particular LPE for his work on
finding a testcase!
closes#724, #731
Have
```xml
<body t-name="webclient" />
```
and
```js
const comp = new WebClient();
comp.mount(document.body, {position: 'self'});
```
Before this commit, the body that was there before anything had happened
was *replaced* by the new body node created by the WebClient OWL component
After this commit, we ensure that the element body is the same at reference level
In most cases, we just want Component<any, Env>. But since it was so
annoying to have always the type Env, we actually used
Component<any,any> everywhere.
With this commit, the generic types have a default (and their order is
swapped), so we can simply use Component in most cases, and
Component<Props> when we want to type the props.
Géry Debongnie