I am new to React so please excuse me if this is a noob question but I really could not find the answer in the DOCs or elsewhere.
Let's say I have two buttons with a counter that share the state but are far away from each other in terms of the placement in the UI.
The documentation says the common owner component for both buttons should own the state. It makes sense if the components are next to each other like in the example but what if my buttons are each part of a different UI group and are far away in terms of nesting? My state holder would be the root of the document and I would have to pass a handler function down through many layers. And what if I need to add new component somewhere else that also needs to know the state? Would I have to modify all the parent components in the way to pass the state down? That is tremendously impractical.
Without React I would have some global Subscribe/Publish pattern like jQuery Observer and all UI elements could subscribe/publish to it regardless of their nesting position.
How does React solve this?
Related question: If I need to load/save the state to DB, how do I pass a reference of the controller (or Whatever) to each React component that stores the state?
1 for global state you may use REDUX
Redux is a predictable state container for JavaScript apps
for connect/subscribe component with that state ,you should use react-redux
If components are far away in terms of nesting, you may connect/subscribe them to redux store, and take only neccessary part of state. They will update if only neccessary part is changed.
article that explains how you can do your case
to learn how to use redux you can watch this videos from creator of redux (Dan Abramov)
1.getting-started-with-redux
2.building-react-applications-with-idiomatic-redux
3.I definitely recommend to you discordapp rectiflux channel. because you allways can ask any question online.(there you can find contributors of that tools)
2 alternative way that less verbose then redux is MobX
MobX is a battle tested library that makes state management simple and scalable by transparently applying functional reactive programming (TFRP). The philosophy behind MobX is very simple:
Anything that can be derived from the application state, should be derived. Automatically.
I suggest to look at the Flux stores. In short, stores are like model in your application. You can listen to change (subscribe) and also modify their properties (publish). You can see how it was done in example app.
A better option is to go with Redux.
Redux is enabling use cases like yours in a way simpler fashion :)
It will help you with all the state and make your life much easier.
Some good resources for learning:
The Redux Website
Video courses from Dan Abramov, the creator [Free]
Awesome course on Udemy [Not free]
Building Applications with React and Redux in ES6
And finally take a look at this youtube series [Free]
Managing state in the middle layers of your app should be avoided where possible. This data belongs in a store, which holds the global state of the app. Then each component accesses the state via its props.
The naïve approach to get the data down to the component is to pass the store through all the layers of your app "manually", i.e. through props.
Smarter alternatives exist, which use connected components, that access the global state through the context (as opposed to the props). Typically, the presentational component (your button component) is wrapped in a container component that handles this connection to the store, then passes the data in via props.
There are numerous frameworks that facilitate this process, links to which are already provided in the other answers.
If you are trying to share simple states, try this ( I am the author): react-provide-state
Otherwise I will recommend Redux. It has become the most popular tool for managing application states.
In the applications being working on, we use Redux to manage the main application states and almost all other states. But we use 'react-provide-state' for simple, UI only states like Modal, Checkbox states.
Related
I have a question regarding the state management when using redux. the main aim of Redux is to globalize the state of the components so every component in the App can read and update that state.
My question is: When we write React/Redux applications, which design pattern we should use? to define every state in the Redux store? or to only define the states that require to be read by other components in the Redux store, and the rest will be encapsulated inside their relative components?
I think you got my question right? :D
Now, how about components' reusability? doesn't redux make it impossible for the components to be reusable?
& Thank yous 😘
There is no “right” answer for this. There are some Recommendations though -
Some common rules of thumb for determining what kind of data should be put into Redux:
Do other parts of the application care about this data?
Do you need to be able to create further derived data based on this original data?
Is the same data being used to drive multiple components?
Is there value to you in being able to restore this state to a given point - in time (ie, time travel debugging)?
Do you want to cache the data (ie, use what's in state if it's already - there instead of re-requesting it)?
Do you want to keep this data consistent while hot-reloading UI components (which may lose their internal state when swapped)?
From Redux Github -
Question: How to choose between Redux's store and React's state? #1287
dan_abramov - Use React for ephemeral state that doesn't matter to the app globally and doesn't mutate in complex ways. For example, a toggle in some UI element, a form input state. Use Redux for state that matters globally or is mutated in complex ways. For example, cached users, or a post draft.
Sometimes you'll want to move from Redux state to React state (when storing something in Redux gets awkward) or the other way around (when more components need to have access to some state that used to be local).
The rule of thumb is: do whatever is less awkward.
Cheatsheet -
I am building a web app where redux is configured and app is fairly large.
Now I want to store some user preferences which will be available as part of an API respopse.
As this data is required to the majority of components I am planning to store data in the context and wrap application using the context.
I have Few questions regarding approach.
Will considering context impact the performance?
As Redux is already configured which internally uses the Context. So should we continue to use redux for user data.
Is it good practice to use Redux and Context together.
Context and Redux are very different tools that solve different problems, with some overlap.
Context is not a "state management" tool. It's a Dependency Injection mechanism, whose only purpose is to make a single value accessible to a nested tree of React components. It's up to you to decide what that value is, and how it's created. Typically, that's done using data from React component state, ie, useState and useReducer. So, you're actually doing all the "state management" yourself - Context just gives you a way to pass it down the tree.
Redux is a library and a pattern for separating your state update logic from the rest of your app, and making it easy to trace when/where/why/how your state has changed. It also gives your whole app the ability to access any piece of state in any component.
In addition, there are some distinct differences between how Context and (React-)Redux pass along updates. Context has some major perf limitations - in particular, any component that consumes a context will be forced to re-render, even if it only cares about part of the context value.
So, yes, you can use them both in the same app, in the same way you can use a hammer and a screwdriver together on the same construction job.
For more details, see my posts:
Why React Context is Not a "State Management" Tool (and Why It Doesn't Replace Redux)
React, Redux, and Context Behavior
A (Mostly) Complete Guide to React Rendering Behavior
Will considering context impact the performance?
Since you want to share user preferences that (I guess) do not change often, you could use a React context to share that data.
But performance issues arise when you put multiple different data in one React context that update at different rates. This is because every component that uses the context will be rerendered even if the part of the context it is interessted in did not change. In this case you can split the context and use one context for each part of the data.
Since you want to use the context to share an application state, you should use Redux. In Redux you use selectors to select a part of the application state. This useSelector hook is implemented in a way that it only triggers a rerender of the component if the selected part changes. You can even pass it an equality function if you want to change the way state change is detected.
As Redux is already configured which internally uses the Context. So should we continue to use redux for user data.
I would say: yes, continue with Redux.
Since you already use Redux you should not spread your application state management over different concepts. Put the user settings in the Redux store (like any other application state) and don't handle them special.
Is it good practice to use Redux and Context together
Well, Redux is based on the React context. So if you use Redux it is already a good practice.
If you mean using both for application state management, I think you should go the Redux or the React context way. Mixing them makes it harder to understand where state is managed.
I am using Redux heavily in my application. I also have a very limited number of properties stored in Context:
username of currently logged-in user
screen geometry information (to adapt whenever browser window resizes)
Is this an antipattern and should I move everything over to Redux and dispense with Context altogether? I am inclined to answering yes. So the question is:
Are there valid use cases for using both Context and Redux in the same app or is it a code smell?
No I can't think of a single reason why it would be a good idea to use both.
Generally "if you are using Redux only to avoid passing props down to deeply nested components, then you could replace Redux with the Context API".
If you need more advanced features, like predictable state container, async actions and so on, then choose Redux.
Pardon the pun, but "context switching" between the two is only going to confuse you, your app and future developers on your app.
in your case, username stuff definitely could belong in a redux reducer and screen geometry information feels like it is basic enough to live in React and be passed down as props. although, this of course can be stored in Redux state too
I want to distribute a React App as a React component. Currently it uses Redux to manage its state. If the end user also uses Redux to manage the state, there will be nested Providers. Would it be a problem or should I pass the store as a prop as Dan suggested here? I personally do not like the second way tho.
Thanks a lot
As you're building a component to be consumed like any other black-box components, using redux internally and your own <Provider> is a fine option.
This will hide the parent app's store from your component but you don't want to access it anyways; it may not exist. Any data you want must be passed in through your top-level component's props.
Likewise, you don't want the parent-application to get data from your internal Redux store through Redux and you don't want any actions to go through both stores as there could easily be name conflicts and unwanted side effects.
Most people only think of Redux as an application-level state management solution and thus the negative comments. In your case your component is big enough to have a component-wide state management solution, and thus Redux for your component is appropriate.
All that said, I realize this post is several years old, so this answer is for others that stumble across this question (as I did). I would be interested in hearing in a comment what you ended up doing and how it worked out.
My question is, should I still be using stateful React components or should I move that state into the Redux store?
There is no single true answer for you question.
You have different types of states. You have a state of your models (in terms of MVC) and UI (View) state. In classical MVC your models should not depend on UI. So, here we have a question: is it ok to save UI state (inputs, checkboxes state) in global redux store.
The most general rule, in this case, is to use common sense :). You can choose any of the approaches depending on your needs and it will be ok if it suits better for your situation.
But, let's look at several examples.
global redux store for everything
I know apps, that save whole UI state in global redux store. I mean that every keystroke in any field will fire event and will update the global store.
Pros:
It is easy to track state changes when the whole state is in one place.
You can serialize the whole state for debugging purposes. It can be automatic state saving on errors. Or QA engineer can dump UI state with a special keyboard shortcut and send to developers. Developers can take this serialized state and restore whole UI as it was on QA's machine.
Cons:
Rerender the whole app on every keystroke.
A lot of intermediary state (in global store) that is needed only while user entering some data.
Passing state down to your components. You will use "Container" components for this but the question is should your "Container" components be only top-level components or you should wrap leaf dump components in containers. Both variants are acceptable but in most cases it is better to move state higher (while it makes sense). Read about "Smart vs Dumb" components or "Containers vs Presentational components"
You should manage different types of state (from different sources) in one global store.
UI state in your components.
For example, you have a form. And your form manages the state on your inputs by its own. So you just render it as <Form onSubmit={ (fields) => saveFields(fields) }>
Pros:
Intermidate form state is private to form. You can think that this state does not exist at all, it does not matter for you.
The shape of private state is much easier to change.
Components are more coherent. They are more independent, like simple mini applications inside your larger application.
Cons:
Other components cannot access this state.
There is no single place of storing state.
Different appoaches to state management.
Increases possibilty of situations when there will be more than one source of thruth.
Additional resources:
Presentation from ReactConf 2016 about possible options for managing state in ReactJS apps
Dan Abramov's great post about "Container" and "Presentational" components
Great video tutorial from Dan Abramov "Getting started with redux". It shows how to use presentational components and how to manage app state.
Some general ideas that can be useful:
Handle as less state as possible in your components but not less than required. Stateless components are easier to work with. But remeber that the state will be moved somewhere, so you will need to handle it in any case (it can be store, or presentational wrapper component etc).
Make your components as much independent as possible. You can make good independent components with private state or make them stateless.
Split components into presentational components (context independent) and container components (context dependent).
Move state as high as possible. Prefer saving state in upper level components. It can be not only container components. You can create presentational components that wraps you stateless components just to manage state (they will have no connection to redux)
I recommend reading this Medium post: Presentational and Container Components. It outlines the ideas of using component state for UI state but non-UI state is global (redux). It also suggest a pattern of how to approach that by having container components responsible for managing access to the global state and simple view components that the container passes state to as a prop.
So the answer is a little more complicated in my opinion because there are different types of state.
I highly recommend this free video series that goes into Redux in depth and provides a lot of explanation to build your knowledge up quickly: Getting Started with Redux.
After digging into Redux more and using it on a project to learn, I found myself making use of it to store UI state. The particular use case was a long scrolling div. I wanted the scroll position of the div to be the same when the back button was used. It was super easy to hook the click up to a dispatch to update the state for the current div.scrollTop and then on componentMount (back button pressed, component remounts) simply set the div.scrollTop to the position from state.
So I think it can be very useful to have UI state in Redux too. It is easier to reason about and simple to do. I can see building very powerful UIs this way that do not exhibit the typical UI issues seen with single page applications.