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!
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 (i.e. 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.
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Let's say I have a blazor component that uses a lot of resources to create an animation, it doesn't make sense to keep rendering it if the user scroll past the component (i.e. the component not visible in the screen). Is there a way to detect this using Blazor?
I am aware that I can rely on Intersection Observer API with JS, but I am looking for something in Blazor/C#.
Thanks,
I have a component that is sometimes pushed as a regular screen on top of the stack, and sometimes shown as a modal.
When a specific event occurs, I need to get rid of the component. But I don't know if it's a modal or a regular screen, so I don't know if I need to call Navigation.pop(componentId) or Navigation.dismissModal(componentId). Is there a way to check before calling?
I tried just calling both in succession, but then one of them fails and throws an error.
I could wrap them both in a try/catch, but that seems like an anti-pattern. What is the recommended way to deal with this?
You can use a command listener and track when it's pushed or shown as a modal
Consider the TextInput component of React Native. It has a prop called value. I set the value to this.state.text.
It also has a prop onChangeText, which I set to (text) => {this.setState({text: text}).
Setting the state will cause the view to re-render, which will in turn trigger setValue on the component.
This doesn't cause any sort of recursion or undesired behavior with stock components. However, in building my own text input component, I'm finding that using state in value and in onChangeText causes native input events to re-render the view and call setValue.
i.e user types on keyboard, native module emits onChangeText event, JavaScript component receives event and updates state, state change causes re-render, re-render calls setValue on the native component, and the native component swaps out the text with the value received from the initial event (the same value).
The problem is, when you set the text on an iOS or Android native text component, it resets the cursor. So I tried putting in a conditional if(newText != currentText) {setText(newText)}, and this works when you type slow, but when you type fast, things get chaotic and you can't predict the order of events.
I looked at how the React Native authors handle this in their own text component, and they seem to be using some sort of counter (here and here) to synchronize events, but I couldn't keep up with the logic as it was all over the place.
For now, my solution is to not use state in the render function, but then my component depends on render not being called unexpectedly to function properly, and that's just a disaster waiting to happen.
Any insight as how to better design a component like this, or how RN components get around this issue?
I've got a app that has a collection of scenes, and make many calls to a remote server that because they control hardware can take quite a while. In my redux store I have a variable that represents if there are any requests inflight.
What I'm trying to achieve is having a spinner or loading scene defined in a single place, and having automatically show dependent on the state of variable in the redux store.
I think that the answer lies in having a modal scene for the loading page, but the bit I'm missing is how to have it automatically displayed (and hidden) based from the state in the store. I don't want to call Actions.loadingScene() from all the places that makes the requests.
I've got a reducer in place that see's all the actions (both the application and the RNRF actions), but I couldn't work how what state I had to mutate to get it to display the modal scene.
Any pointers would be great!.
It appears that redux-saga would be the way to solve this, however I ended up making a HOC that adds the spinner, and displays it when required. It does mean that I have to remember to wrap all scenes with the HOC but that it OK.
I'm building an app which views are inside tabs.
Some of the views render lists from data fetched by a call to an api.
I noticed that the render method is callled every time I hit the tab.
This causes the render method to re-render the list, so there is a delay and this not user friendly at all, as it takes some time.
How can I render the views only once?
You should implement shouldComponentUpdate method for each react component
you don't want to re-render each time it's props or state changed