Skip to main content

Building Reducer Using Redux Toolkit

Redux Toolkit is one of the libraries that can help us manage our application state which depends on Redux. It allows us to create reducers within our application and separate each reducer from one another based on any criteria that we desired in a specific kind of module. There are some approaches that we can utilize to build reducers in Redux Toolkit.


Basic Shape
const slice = createSlice({
    // ...
    reducers: {
    	increment: (state) => {
        	state += 1;
        }
    } 
});

On the code above, it seems that we mutate the state, but actually, Redux Toolkit utilizes Immer in the backstage so it will be translated into immutable operation. Then, unlike legacy libraries that require us to manually define the action that will be dispatched to be handled by a specific reducer, Redux Toolkit can generate action creators for us.

const { increment } = slice.actions; // "increment" is the action creator

Then, we can dispatch the action inside our component following any activity we desired.

<button onClick={ () => dispatch(increment()) }>Add</button>

Basic Shape With Payload

Commonly we need to pass a payload to be processed by the reducer. It can be achieved by utilizing the second parameter in a reducer function.

const slice = createSlice({
    // ...
    reducers: {
    	incrementBy: (state, action: PayloadAction<number>) => {
        	state += action.payload;
        }
    } 
});

Reducer With Pre-formatted Payload

Sometimes, we need to pre-format our payload before it is consumed by the reducer. We can declare our reducer as an object with specific properties rather than as a single function as the previous ones.

const slice = createSlice({
    // ...
    reducers: {
    	createArticle: {
            reducer: (state, action: PayloadAction<any>) => {
            	// do something
            },
            prepare: (title, author) => ({
            	payload: {
                    id: uuid(),
                    title,
                    author,
                    createdOn: Date.now(),
                }
            }),
        }
    } 
});

Then, we can pass the parameters which align with the configuration when we dispatch the action.

dispatch(createArticle(title, author));

Dispatching Action with Thunk Function

Originally, Redux Toolkit is integrated with thunk middleware that allows a function to be passed into a dispatch call and to interact with the dispatch and getState methods inside it. It can be used to perform asynchronous logic before dispatching specific actions.

const sampleThunk = (dispatch, getState) => {
  setTimeout(() => {
    const currentState = getState();
    dispatch(increment());
    const nextState = getState();
  }, 2000);
}

dispatch(sampleThunk)

If we want some data to be passed to the function, we can create a wrapper for that.

const sampleThunk = (amount) => (dispatch, getState) => {
  setTimeout(() => {
    const currentState = getState();
    dispatch(incrementBy(amount));
    const nextState = getState();
  }, 2000);
}

dispatch(sampleThunk(10))

Asynchronous Thunk using createAsyncThunk

The createAsyncThunk function will generate a thunk function that can provide a mechanism to interact with the store or auto-dispatch certain actions. It can be used when we want to monitor the states of asynchronous calls and then perform any action related to it. The function accepts two parameters, the first is the action name, and the second is the payload creator.

const getAllArticles = createAsyncThunk('article/getAllArticles', async (data?: any) => {
  const response = await client.get('http://localhost:3000/article');
  return response.data;
});

Now, the getAllArticles function can be passed into a dispatch call.

dispatch(getAllArticles());

Besides that, the variable will be appended with additional action creator properties related to an asynchronous activity that can be read to initiate specific actions and handled by reducers. The properties are pending, fullfiled, and rejected. Now, we can create extra reducers in our slice definition.

const slice = createSlice({
    reducers: {
    	// ...
    },
    extraReducers: (builder) => {
      builder
        .addCase(getAllArticles.pending, (state) => {
          // do something
        })
        .addCase(getAllArticles.fulfilled, (state, action: PayloadAction<Article[]>) => {
          // do something
        })
        .addCase(getAllArticles.rejected, (state, action) => {
          // do something
        });
  },
});

We can also perform additional actions in our component related to asynchronous results other than what is performed in the slice by using the unwrap method which is available when the dispatch function is instantiated.

try {
	await dispatch(getAllArticles()).unwrap()
	// do something
} catch (err) {
	console.error('Failed to get the articles: ', err)
} finally {
	// do something
}

Comments

Popular posts from this blog

Rangkaian Sensor Infrared dengan Photo Dioda

Keunggulan photodioda dibandingkan LDR adalah photodioda lebih tidak rentan terhadap noise karena hanya menerima sinar infrared, sedangkan LDR menerima seluruh cahaya yang ada termasuk infrared. Rangkaian yang akan kita gunakan adalah seperti gambar di bawah ini. Pada saat intensitas Infrared yang diterima Photodiode besar maka tahanan Photodiode menjadi kecil, sedangkan jika intensitas Infrared yang diterima Photodiode kecil maka tahanan yang dimiliki photodiode besar. Jika  tahanan photodiode kecil  maka tegangan  V- akan kecil . Misal tahanan photodiode mengecil menjadi 10kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 10 / (10+10) x Vcc V- = (1/2) x 5 Volt V- = 2.5 Volt Sedangkan jika  tahanan photodiode besar  maka tegangan  V- akan besar  (mendekati nilai Vcc). Misal tahanan photodiode menjadi 150kOhm. Maka dengan teorema pembagi tegangan: V- = Rrx/(Rrx + R2) x Vcc V- = 150 / (150+10) x Vcc V- = (150/160) x 5

Setting Up Next.js Project With ESLint, Typescript, and AirBnB Configuration

If we initiate a Next.js project using the  create-next-app tool, our project will be included with ESLint configuration that we can apply using yarn run lint . By default, the tool installs eslint-config-next and extends next/core-web-vitals in the ESLint configuration. The Next.js configuration has been integrated with linting rules for React and several other libraries and tools. yarn create next-app --typescript For additional configuration such as AirBnB, it is also possible. First, we need to install the peer dependencies of eslint-config-airbnb . We also add support for Typescript using eslint-config-airbnb-typescript . yarn add --dev eslint-config-airbnb eslint-plugin-import eslint-plugin-jsx-a11y eslint-plugin-react eslint-plugin-react-hooks yarn add --dev eslint-config-airbnb-typescript @typescript-eslint/eslint-plugin @typescript-eslint/parser After that, we can update the .eslintrc.json file for the new configuration. { "extends": [ "airb

Configuring Swap Memory on Ubuntu Using Ansible

If we maintain a Linux machine with a low memory capacity while we are required to run an application with high memory consumption, enabling swap memory is an option. Ansible can be utilized as a helper tool to automate the creation of swap memory. A swap file can be allocated in the available storage of the machine. The swap file then can be assigned as a swap memory. Firstly, we should prepare the inventory file. The following snippet is an example, you must provide your own configuration. [server] 192.168.1.2 [server:vars] ansible_user=root ansible_ssh_private_key_file=~/.ssh/id_rsa Secondly, we need to prepare the task file that contains not only the tasks but also some variables and connection information. For instance, we set /swapfile  as the name of our swap file. We also set the swap memory size to 2GB and the swappiness level to 60. - hosts: server become: true vars: swap_vars: size: 2G swappiness: 60 For simplicity, we only check the exi

Managing MongoDB Records Using NestJS and Mongoose

NestJS is a framework for developing Node.js-based applications. It provides an additional abstraction layer on top of Express or other HTTP handlers and gives developers a stable foundation to build applications with structured procedures. Meanwhile, Mongoose is a schema modeling helper based on Node.js for MongoDB. There are several main steps to be performed for allowing our program to handle MongoDB records. First, we need to add the dependencies which are @nestjs/mongoose , mongoose , and @types/mongoose . Then, we need to define the connection configuration on the application module decorator. import { MongooseModule } from '@nestjs/mongoose'; @Module({ imports: [ MongooseModule.forRoot('mongodb://localhost:27017/mydb'), ], controllers: [AppController], providers: [AppService], }) Next, we create the schema definition using helpers provided by NestJS and Mongoose. The following snippet is an example with a declaration of index setting and an o

Enabling Single Webcam for Multiple Applications Access in Linux

A webcam can not be accessed by two or more applications simultaneously. The solution is you can duplicate the video stream and make it available for any application. In short, you create a virtual webcam. First, a webcam is commonly detected on  /dev/video* . Before you go through the steps to duplicate video stream, you should check whether your webcam is working. You can try to capture video using VLC by this command. (For example, your webcam is on  /dev/video0 ) $ vlc v4l2:///dev/video0 If it doesn't work, you can try to change its mode to 0777 and make sure there are no other applications accessing it. If it still doesn't work, you can buy a new webcam. Seriously. Don't buy a cheap and unknown-brand webcam. I have $5 webcam and it had wasted my time. $ apt-get install ffmpeg linux-generic v4l2loopback-dkms FFmpeg is the main application that will access your webcam and duplicate its video stream. V4L2loopback is needed to create multiple virtual capture devic

Configure Gitlab SMTP Setting

Gitlab CE or EE is shipped with the capability to send messages through SMTP service as the basic feature to send notifications or updates to the users. The configuration parameters are available in /etc/gitlab/gitlab.rb . Each SMTP service provider has a different configuration, therefore the Gitlab configuration parameters should be adjusted according to the requirements. Some examples have been provided by Gitlab here . This is an example if you use the Zoho service. gitlab_rails['smtp_enable'] = true gitlab_rails['smtp_address'] = "smtp.zoho.com" gitlab_rails['smtp_port'] = 587 gitlab_rails['smtp_authentication'] = "plain" gitlab_rails['smtp_enable_starttls_auto'] = true gitlab_rails['smtp_user_name'] = "gitlab@mydomain.com" gitlab_rails['smtp_password'] = "mypassword" gitlab_rails['smtp_domain'] = "smtp.zoho.com" This is another example of using Amazon SES w