My App.js looks roughly like this:
<HorizontalNavigation />
<DataPanel />
The HorizontalNavigation component contains a Button to export the DataPanel containing charts into a PDF File. This already works fine. Now there is one tiny thing I need to do on the Chart components before I export them.
I am a react beginner, but when I understand correctly a basic solution would be to lift state up to a common ancestor of HorizontalNavigation and DataPanel. That would feel weird as I would have to reach down that state to a lot of intermediate components from DataPanel to the actual charts components. Also they would all be rerendered when this is not necessary at all.
What I had in mind is to use an observable pattern where the PDF export button notifies all charts to do their thing before exporting. How would you design such a pattern in react? The PDF Export button would be my subject to which the charts observers had to attach. But as I don't have a reference to the subject, how do observers attach?
As I'm a react beginner there might be a much more simple solution I don't see yet. So I also appreciate suggestions for other solutions.
What you are looking is state transfer between component. Have a look at below link
https://reactjs.org/docs/hooks-reference.html#usecontext
Related
I want to build a simple app like in picture attached with react js, I just cannot find the right idea of:
How to "select" photos(or item) in an application and have the "cart"-like component appear at the bottom when at least one photo/item is selected(and close and deselect all already selected photo/items) and expand the cart-like component at the bottom when clicked to show what's been already selected.
What is the best approach to this?
P.S I'm new to react with a big idea in mind xD
app's view
This question definitely needs more information, but I will try to point you in the right direction. There are hundred of ways to create the UI/functionality you are describing but here is a very generic overview;
The "items" (Img1-6) looks like a grid of ShopItem components, possibly in a CSS Grid / flexbox. Each ShopItem would probably make use of an onClick method to "do something" when it is clicked - this may involve updating a state (using the useState react hook) somewhere which tells you if a ShopItem is checked or not. It could also potentially use a callback method to do something in the parent when the items are checked.
I imagine that each ShopItem may own its own "checked" state or may update a global state (Such as Zustand or Redux) or a Context (React) when it is toggled on and off. The checked state of a ShopItem would also inform the UI of the component.
The "cart-like" component could be looking at the global state/context/callback from the item component, and could change based on its value and how many checked items there are. (Eg/ checkedItems !== 0 ? show : don't show)
This is just one way in which this UI can be built, if you would like a more specific solution, please edit your question to include code snippets and what you've already tried.
I've posted this on Reactiflux but may get more traction here. I've created a sandbox to demonstrate my need: https://codesandbox.io/s/xvnk0znw7z
What I'm trying to do is create a generic modal wrapper that I can use to encapsulate several components; in the sandbox, the component is a date range picker, but I also have a formik component for example.
The thing is, the Apply and Clear buttons need to be a part of the wrapping modal, and not the child component it wraps.
However, when clicking on Apply or Clear, saving the child component state to the Context (not included for brevity) is really the responsibility of the child component itself; only it knows how it should do it.
In the example above, that would be the ok and clear methods of DatesPicker. Intuitively, I would call children.ok and children.clear from the wrapping modal, but I know for a fact that's not how it should be done.
I looked a lot at the Cat and Mouse render-prop example in React's docs, but I can't get my head around how I can apply this here.
I am looking for a good code pattern to allow some communication between components, when using React & Redux.
Most likely this communication should be done via redux, like many articles suggest. (like this one, for example).
However, there are some situations when using the store would be a bit of a hack rather then using it for state management. These special cases are usually when you need to give a command to a component, like show or hide.
I will give an example:
Lets say that we have a <Tooltip /> component which all it does is render some help icon, that when clicked, opens a tooltip popup.
And lets say that we have more than one in a page, but we want to make sure that only one is open at a given time. So if tooltip A is open, and the user clicks on tooltip B, then B should open and A should close.
Here are some patterns that I thought might be relevant to implement this requirement:
Using Redux: We could have in the store some state for these tooltips:
{
showTooltip: "A" // the ID of the tooltip to show
}
This means that we have to connect the tooltips to the redux store, and check for each tooltip if it's ID is the one that should be opened, and when the user clicks on the tooltip icon, we dispatch an action to set the opened tooltip.
Using additional event mechanism: We can use an additional event mechanism to Redux, like emitter.
In this case we can fire an event whenever a tooltip is about to be opened, and all other tooltips can listen and hide themselves once they get such an event.
I have to say that it seems to me that maybe having two event mechanisms in the app seems a bit redundant, but on the other hand, using redux store to communicate with components seems a bit overkill.
Would love to hear some opinions about this issue.
The React and Redux world generally encourages representing your app's behavior as state. For example, rather than an imperative $("#someModal").show() command, you might save a flag value somewhere that says {modalVisible : true}.
There's numerous examples of using state to drive modals and popups. A typical implementation would store the values for a single modal or a list of modals in state somewhere (either in a parent component or in Redux), and then render modal components as appropriate based on those values, such as: {type : "notificationPopup", level : "warning", message : "Something happened!"}. The basic approach works whether you're storing the data in React, Redux, MobX, or something else.
For specific examples, see Dan Abramov's answer to "How can I display a modal dialog in Redux?", Dave Ceddia's article "Modal Dialogs in React", the article "Scalable Modals with React and Redux". I also have other articles that demonstrate modal management in the React Component Patterns#Modal Dialogs and Redux Techniques#UI and Widget Implementations sections of my React/Redux links list.
According to the docs, one should avoid having multiple components with state. I am in the situation where I want to make a text box that automatically expands vertically as the user writes, and for that I'm using this trick http://www.impressivewebs.com/textarea-auto-resize/, which means I need to get the height of a component. Now, I've been playing around with it a bit, and it doesn't seem feasible to pass a ref to my parent component which contains state, so the easy way out would be to keep a piece of state in the component with the textbox, and then use the ref from there.
This got me thinking, how exactly do multiple state components negatively affect my app? Is it only maintainability / comprehensability? Or are there actual performance issues with it? I've noticed a lot of open source react components that you would just plug in to your app keep state, meaning if you use open source components, chances are you will have several state components in your app.
It's totally ok to use local state for this kind of tricks on DOM. It's even better approach, than to share such implementation details to parent components.
In general, use this places for state:
Application-wide data in stores outside React (redux, flux-store, observables)
Form temporary data can be placed in store also. But if don't need it anywhere else except form, it's better to place this data in form component.
Tricks on DOM, short living and very local state can be placed in component that just need it
are there actual performance issues with it?
No. If you'll place all your state in components, your application will become even faster. Because when you update local state, only this component and it's childs updates.
But you shouldn't do that, because it kills maintainability.
lot of open source react components that you would just plug in to your app keep state
If component doesn't allow you to control it through the props - it's bad component. Usually open source components written to be easier to use, so they provide nice defaults, that allow you to just place component to your application, and be happy with that.
For example, Tabs component usually controlls selected tab using local state. But also it takes selectedTab and callback onSelect, so you can control it by yourself.
Stupid components (like your textarea component) should not have state with data. But they can have their own UI state.
In this case you can easily keep textarea height in state of stupid component.
I've designed a pretty simple responsive layout (be sure to open link with Chrome) and now I'm trying to implement it in React. I've attached some screenshots of the layout as well.
This app is supposed to be the typical tab/nav app, but due to the responsive layout, the view hierarchy is pretty awkward to work with in React.
I've built a React component called Layout to abstract away all the layout stuff. Layout also has props for renderLeft, renderRight, title, and onTab. Layout's children are then rendered into the content block.
The easy solution would be to make Layout a child of the current view and render whatever you want. However, this is going to mess up some animations I had in mind. I want to have a CSSTransitionGroup element wrapped around the tabbar, the title, and the left and right buttons animating them as they change. Thus, the Layout element must remain the same between the views else a new CSSTransitionGroup element will be rendered for each view which isn't good.
So now the problem is that I have a Layout component with a view rendered as its child (but sort of as sibling with respect to the App component), but the view needs to specify renderLeft, renderRight and title for the Layout which is its parent! For example, in the top-level App component, the render function may look like the following, and I need some way of setting Layout's renderLeft from the View.
render() {
return (
<Layout renderLeft={??}>
<View setRenderLeft={??}/>
<Layout/>
)
}
The only thing I've thought of so far seems totally like the wrong way of doing it:
In the top-level App component, have a state variables for renderLeft, renderRight, and title and App passes those to the Layout props. Now for the view, pass some functions like setRenderLeft, setRenderRight, and setTitle which will change the App state and thus change the Layout. We can thus call these functions in componentWillMount for each view.
This just seems like a total hack and seems to break the whole idea of one-directional-data-flow. However, I'm not sure how else to do it! Are there any more proper ways of doing this? I'm reminded of the concept of delegation when building iOS apps, but thats very OOP and not very FP.
Any ideas?
Your question is a little difficult to tell exactly what the issue is, however if I were you I would read up on https://facebook.github.io/react/tips/communicate-between-components.html
For communication between two components that don't have a
parent-child relationship, you can set up your own global event
system. Subscribe to events in componentDidMount(), unsubscribe in
componentWillUnmount(), and call setState() when you receive an event.
Flux pattern is one of the possible ways to arrange this.
You want to either have the siblings talk to the parent and communicate there, or at the global level.
Hope this helps.