渲染前后的海边挂钩

Question

I wanted to see if there is a hook in Seaside that is called before rendering, and one after rendering. It happens to me that I want to show a notification on the screen, and I would like that once the rendering is finished, this component is modified so that the next time the rendering is done, it is no longer displayed.

Thanks and regards!

Answer 1

Instead of 'hooks', Seaside has component decorations that you can wrap around a component to change their behaviour. If you wrap your root component, you can implement a decoration that invokes hooks before and after rendering on your entire component tree.

However, changing the state of your components while rendering will break the state backtracking behavior that Seaside offers you. The state changes should happen in the action callbacks. So, there is no 'after rendering' phase where you can change the state of your component (well, you can, but it will lead to subtle problems ). Instead, use the action phase (ie callbacks) to change the state of your component such that the next time the rendering phase is invoked, your component is not displayed.

I'm assuming that when you say 'the next time the rendering is done', this means after the user has clicked a link or done some other action. This means you can change state while executing the action callback and arrange the state of your rendering tree such that the concerned component is no longer shown. If you do it like this, the user will see the component again when he clicks the back button in the browser.