Where should I put API calls? - react-native

Fairly new to React Native, I would like to apply proper "good practices" to my first project. I'm trying to build an Hacker News client.
You can find it here: https://github.com/napolux/hnative and as you can see I'm at the very beginning of my project.
I'm willing to separate the API calls I made to get the news from the component ItemList where they currently are. My goals is to maximize code reuse.
In pseudo-code, this is what I do:
componentDidMount = () => {
this.makeApiRequest();
}
makeApiRequest = () => {
// Ask for data
// Save data in component state
}
render = () => {
// Use data to render stuff...
}
I'm still puzzled by redux and I'm still not sure if it can fit my needs in any way and help me to organize my code.
Any suggestion?

You're on the right track. The most common mistake is to put your API calls in the componentWillMount lifecycle hook, but you're smarter than most people :)
As with most things, the correct answer though is going to be a dissatisfying "it depends". As you're just getting started, I think you're on the right track though. Keep it simple until simple becomes difficult to manage, then refactor to solve for that complexity.
There are several strategies you can employ. I think you've started with the right "first step". Here are a couple other strategies you might want to investigate though when the time is right.
Container Components
You're basically wrapping your stateless components in a container responsible for fetching the needed data. This would be your logical "next step". Here's a few articles I have bookmarked on the topic.
https://css-tricks.com/learning-react-container-components/
https://voice.kadira.io/let-s-compose-some-react-containers-3b91b6d9b7c8#.qgg1i13vp
http://krasimirtsonev.com/blog/article/react-js-presentational-container-components
API Helper
This is a strategy I learned from Tyler McGinnis and used on one of my first projects. You'd basically put all your API calls into a single, helper file. When you need to make a call out to an API, you just import it and use it. You could easily combine this with the Container strategy above if you wanted.
https://github.com/geirman/RepairMaps/tree/master/App/Utils
Redux
Redux should be your last stop. This adds a lot of boilerplate to the project and comes at a cost. Keep it simple until you need to solve the problems Redux is really good at solving. How do you know when that is? Dan Abromov wrote a great article on it, so I'll let him tell you so you can make the trade offs yourself.
https://medium.com/#dan_abramov/you-might-not-need-redux-be46360cf367

You could also look into mobx . You can place your API calls in mobx #action methods

Related

What is AsyncStorage *for*?

I can find information on how to write calls to AsyncStorage, how it actually stores information on device, etc., and some basic examples of usage storing keys, but what I'm looking for is a broader understanding of why I would use it.
The reason I'm asking is that I've recently had to refactor one area of our (react-native) mobile-app, which was being buggy and - not unrelated! - had become one unfathomable beast. It was previously a huge single class, and in its componentDidMount/unMount had calls to AsyncStorage, where it was stashing some state variables.
(Judging from the comments, at least part of the reason was to do with the previous developer struggling with understanding how to use/access state within FlatList, but I think it's more than just that)
The refactored code achieves the same goals as before, through several separate functional components, each performing a specific task. Everything FlatList calls is now stateless, and, having just finished testing, all the previous functionality seems to have been matched.
But, I realise I haven't used any calls to AsyncStorage, and I'm left wondering if that is a bad thing? I can imagine that I could stash into AsyncStorage all the state from this part of the app such that if it crashed we could jump back to whatever point we got to. And I suppose that might be handy, in its way. But is that a sensible use of async storage? Is that what y'all are using it for? Was the previous use case a poor one and should I move on without it?
(I appreciate this question is a more concept'y than what I normally look for / ask, and if I should be putting it somewhere else, please do say!)

React Native - Separate View and Logic

Is separate view and logic (like java class and xml in Android) in React Native is best way to increase app performance? Any reference for this guys?
In terms of app performance it wont really matter because in the end it all gets combined into a single JS bundle file. But separating render and business logic is always useful. It lets you rewrite business logic without having to navigate render logic when you want to make a change and also helps reuse business logic elsewhere in your app if you need to.
A simple example is something we evaluated at work, we have a react native application and a react website. A lot of our business logic of API handling data parsing and storage and redux handling was similar if not exactly the same on both platforms. What we realised is that if we write all the business logic separately we could simply write it once and use it on both platforms and only our render logic could change. Now it is more complicated than my explanation of course but it is possible.
Hope this helps.

Angular 6 - Why use #ngrx/store rather than service injection

I am recently learning Angular 6 with #ngrx/store while one of the tutorial is to use #ngrx/store for state management, however I don't understand the benefit of using #ngrx/store behind the scene.
For example, for a simple login and signup action, previously by using the service(Let's call it AuthService) we might use it to call the backend api, store "userInfo" or "token" in the AuthService, redirect user to "HOME" page and we can inject AuthService in any component where we need to get the userInfo by using DI, which simply that one file AuthService handles everything.
Now if we are using #ngrx/store, we need to define the Action/State/Reducer/Effects/Selector which probably need to write in 4 or 5 files to handle above action or event, then sometimes still we need to call backend api using service, which seems much much more complicated and redundant...
In some other scenario, I even see some page uses #ngrx/store to store the object or list of object like grid data., is that for some kind of in-memory store usage?
So back to the question, why are we using #ngrx/store over service registration store here in Angular project? I know it's for "STATE MANAGEMENT" usage, but what exactly is the "STATE MANAGEMENT"? Is that something like transaction log and When do we need it? Why would we manage it on the front end? Please feel free to share your suggestion or experience in the #ngrx/store area!
I think you should read those two posts about Ngrx store:
Angular Service Layers: Redux, RxJs and Ngrx Store - When to Use a Store And Why?
Ngrx Store - An Architecture Guide
If the first one explains the main issues solved by Ngrx Store, it also quote this statement from the React How-To "that seems to apply equally to original Flux, Redux, Ngrx Store or any store solution in general":
You’ll know when you need Flux. If you aren’t sure if you need it, you don’t need it.
To me Ngrx store solves multiple issues. For example when you have to deal with observables and when responsability for some observable data is shared between different components. In this case store actions and reducer ensure that data modifications will always be performed "the right way".
It also provides a reliable solution for http requests caching. You will be able to store the requests and their responses, so that you could verify that the request you're making has not a stored response yet.
The second post is about what made such solutions appear in the React world with Facebook's unread message counter issue.
Concerning your solution of storing non-obvervable data in services. It works fine when you're dealing with constant data. But when several components will have to update this data you will probably encounter change detection issues and improper update issues, that you could solve with:
observer pattern with private Subject public Observable and next function
Ngrx Store
I'm almost only reading about the benefits of Ngrx and other Redux like store libraries, while the (in my opinion) costly tradeoffs seem to be brushed off with far too much ease. This is often the only reason that I see given: "The only reason not to use Ngrx is if your app is small and simple". This (I would say) is simply incomplete reasoning and not good enough.
Here are my complaints about Ngrx:
You have logic split out into several different files, which makes the code hard to read and understand. This goes against basic code cohesion and locality principles. Having to jump around to different places to read how an operation is performed is mentally taxing and can lead to cognitive overload and exhaustion.
With Ngrx you have to write a lot more code, which increases the chances of bugs. More code -> more places for bugs to appear.
An Ngrx store can become a dumping ground for all things, with no rhyme or reason. It can become a global hodge podge of stuff that no one can get a coherent overview of. It can grow and grow until no one understands it any more.
I've seen a lot of unnecessary deep object cloning in Ngrx apps, which has caused real performance issues. A particular app I was assigned to work on was taking 40 ms to persist data in the store because of deep cloning of a huge store object. This is over two lost render frames if you are trying to hit a smooth 60 fps. Every interaction felt janky because of it.
Most things that Ngrx does can be done much simpler using a basic service/facade pattern that expose observables from rxjs subjects.
Just put methods on services/facades that return observables - such a method replaces the reducer, store, and selector from Ngrx. And then put other methods on the service/facade to trigger data to be pushed on these observables - these methods replace your actions and effects from Ngrx. So instead of reducers+stores+selectors you have methods that return observables. Instead of actions+effects you have methods that produce data the the observables. Where the data comes from is up to you, you can fetch something or compute something, and then just call subject.next() with the data you want to push.
The rxjs knowledge you need in order to use ngrx will already cause you to be competent in using bare rxjs yourself anyways.
If you have several components that depend on some common data, then you still don't need ngrx, as the basic service/facade pattern explicitly handles this already.
If several services depend on common data between them, then you just make a common service between these services. You still don't need ngrx. It's services all the way down, just like it is components all the way down.
For me Ngrx doesn't look so good on the bottom line.
It is essentially a bloated and over engineered Enterprise™🏢👨‍💼🤮 grade Rxjs Subject, when you could have just used the good old and trusty Rxjs Subject. Listen to me kids, life is too short for unnecessary complexity. Stick to the bare necessities. The simple bare necessities. Forget about your worries and your strife.
I've been working with NgRx for over three years now. I used it on small projects, where it was handy but unnecessary and I used it in applications where it was perfect fit. And meanwhile I had a chance to work on the project which did not use it and I must say it would profit from it.
On the current project I was responsible for designing the architecture of new FE app. I was tasked to completely refactor the existing application which for the same requirements used non NgRx way and it was buggy, difficult to understand and maintain and there was no documentation. I decided to use NgRx there and I did it because of following reasons:
The application has more than one actor over the data. Server uses
the SSE to push state updates which are independent from user
actions.
At the application start we load most of available data which are
then partially updated with SSE.
Various UI elements are enabled/disabled depending on multiple
conditions which come from BE and from user decisions.
UI has multiple variations. Events from BE can change currently
visible UI elements (texts in dialogs) and even user actions might
change how UI looks and works (recurring dialog can be replaced by
snack if user clicked some button).
State of multiple UI elements must be preserved so when user leaves
the page and goes back the same content (or updated via SSE) is
visible.
As you can see the requirements does not meet the standard CRUD operations web page. Doing it the "Angular" way brought such complexity to the code that it became super hard to maintain and what's worst by the time I joined the team the last two original members were leaving without any documentation of that custom made, non NgRx solution.
Now after the year since refactoring the app to use NgRx I think I can sum up the pros and cons.
Pros:
The app is more organized. State representation is easy to read,
grouped by purpose or data origin and is simple to extend.
We got rid of many factories, facades and abstract classes which lost
their purpose. The code is lighter, and components are 'dumber', with
less hidden tricks coming from somewhere else.
Complicated state calculations are made simple using effects and
selectors and most components can be now fully functional just by
injecting the store and dispatching the actions or selecting the
needed slice of the state while handling multiple actions at once.
Because of updated app requirements we were forced to refactor the
store already and it was mostly Ctrl + C, Ctrl + V and some renaming.
Thanks to Redux Dev Tools it is easier to debug and optimize (yep
really)
This is most important - even thought our state itself is unique the
store management we are using is not. It has support, it has
documentation and it's not impossible to find solutions to some
difficult problems on the internet.
Small perk, NgRx is another technology you can put to your CV :)
Cons:
My colleagues were new to the NgRx and it took some time for them to
adapt and fully understand it.
On some occasions we introduced the issue where some actions were
dispatched multiple times and it was difficult to find the cause of
it and fix it
Our Effects are huge, that's true. They can get messy but that's what
we have pull requests for. And if this code wasn't there it would
still end up somewhere else :)
Biggest issue? Actions are differentiated by their string type. Copy
an action, forget to rename it and boom, something different is
happening than you expect, and you have no clue why.
As a conclusion I would say that in our case the NgRx was a great choice. It is demanding at first but later everything feels natural and logical. Also, when you check the requirements, you'll notice that this is a special case. I understand the voices against NgRx and in some cases I would support them but not on this project. Could we have done it using 'Angular' way? Of course, it was done this way before, but it was a mess. It was still full of boiler plate code, things happening in different places without obvious reasons and more.
Anyone who would have the chance to compare those two versions would say the NgRx version is better.
There is also a 3rd option, having data in service and using service directly in html, for instance *ngFor="let item of userService.users". So when you update userService.users in service after add or update action is automatically rendered in html, no need for any observables or events or store.
If the data in your app is used in multiple components, then some kind of service to share the data is required. There are many ways to do this.
A moderately complex app will eventually look like a front end back end structure, with the data handling done in services, exposing the data via observables to the components.
At one point you will need to write some kind of api to your data services, how to get data in and out, queries, etc. Lots of rules like immutability of the data, and well defined single paths to modify the data. Not unlike the server backend, but much quicker and responsive than the api calls.
Your api will end up looking like one of the many state management libraries that already exist. They exist to solve difficult problems. You may not need them if your app is simple.
NGRX sometimes has a lot of files and a lot of duplicate code. Currently working on a fix for this. To make generic type classes for certain NGRX state management situations that are very common inside an Angular project like pagers and object loading from back-ends

Communicate between two unrelated components

How do you handle communication between components with no common parent in react-native ?
What's the best way to communicate between two unrelated components ?
I did some research and the most recommended way seems to be using context https://reactjs.org/docs/context.html.
There are multiples way to handle a global state, one of them is the new React Context API, but one of the most famous is redux, written by Dan Abramov, who works at Facebook, inspired by flux, an old facebook library to manage global state. There is also Mobx and many others, I suggest you take a look at each one and see what fits you best, it's hard to tell you without knowing your problem. Feel free to ask any other question about one of them

How to handle $dispatch and $broadcast deprecations in Vue.js?

I was working on a large-scale Vue.js application, and I have used broadcast and dispatch tons of places in my application. What's the best way to sit down and change all these? Or do I have some other way to deal with these breaking-changes?
Both these methods now are merged in the $emit method.
Unfortunately, replacing every instance of $broadcast and
$dispatch with $emit will not work because the pattern
used to manage events the one of the 'event emitter' now.
In my opinion the quickest way to deal with this deprecation is to create a spurious Vue instance and use it as an event hub.
I recently faced the same issue as you since I used a lot $broadcast and $dispatch. The solutions are:
as the previous answer points out, using a component as an event hub for managing your app state;
using vuex. I took some time to analyse the options and really felt that vuex was the way to go. Vuex provides you a central structure to manage all your app state and event and provides great out-of-box utilities that you can easily bring to your components. It also makes the code more modular and easier to rearrange and work with. At least in my opinion. I started using it 2 weeks ago and I'm really thrilled with it. If you take the time to learn I think it may be worth.
Cheers