This blog is about simple actions and reducers required in shopping cart app. Here I am not going to write down all the UI used for it, its only about how you can manage your state in redux store and update it accordingly.

Here I am writing actions and reducers for these five scenarios

Add to cart
Remove from cart
Increase quantity of product
Decrease quantity of product
Discard cart

First we need to create three files actionTypes.js, actions.js and reducer.js. So first thing first we'll write our actionTypes.js file and define our all action types there like this.

export const ADD_TO_CART = 'ADD_TO_CART';
export const REMOVE_FROM_CART = 'REMOVE_FROM_CART';
export const ADD_QUANTITY = 'ADD_QUANTITY';
export const SUB_QUANTITY = 'SUB_QUANTITY';
export const EMPTY_CART = 'EMPTY_CART';

Our actions.js will look like this now

export const addToCart = id => {
  return {
    type: ADD_TO_CART,
    id
  };
};
export const removeFromCart = id => {
  return {
    type: REMOVE_FROM_CART,
    id,
  };
};
export const subtractQuantity = id => {
  return {
    type: SUB_QUANTITY,
    id,
  };
};
export const addQuantity = id => {
  return {
    type: ADD_QUANTITY,
    id,
  };
};
export const emptyCart = () => {
  return {
    type: EMPTY_CART,
  };
};

Here you need to import ur action types from actionTypes.js file above. In actions we are only getting id of products and returning to reducer with its respective action type and id. Empty/Discard cart action doesn't need any id, it will discard the whole cart.

Before writing reducer, I want to show you the sample of my products json:

"products": [
    {
      "id": 1,
      "name": "Perfume",
      "image": "https://image.shutterstock.com/z/stock-photo-vintage-red-shoes-on-white-background-92008067.jpg",
      "price": 200,
      "quantity": 1,
      "selected": false
    }
]

Now the real work is done in reducer.js

const initialState = {
  products: [],
};
const ShoppinReducer = (state = initialState, action) => {
  switch (action.type) {
    case ADD_TO_CART:
      return {
        ...state,
        products: state.products.map(product =>
          product.id === action.id ? {...product, selected: true} : product,
        ),
      };
    case REMOVE_FROM_CART:
      return {
        ...state,
        products: state.products.map(product =>
          product.id === action.id
            ? {...product, selected: false, quantity: 1}
            : product,
        ),
      };
    case ADD_QUANTITY:
      return {
        ...state,
        products: state.products.map(product =>
          product.id === action.id
            ? {...product, quantity: product.quantity + 1}
            : product,
        ),
      };
    case SUB_QUANTITY:
      return {
        ...state,
        products: state.products.map(product =>
          product.id === action.id
            ? {
                ...product,
                quantity: product.quantity !== 1 ? product.quantity - 1 : 1,
              }
            : product,
        ),
      };
    case EMPTY_CART:
      return {
        ...state,
        products: state.products.map(product =>
          product.selected
            ? {...product, selected: false, quantity: 1}
            : product,
        ),
      };
    default:
      return state;
  }
};
export {ShoppinReducer};

so that's it, you get a basic functionality of cart done. I hope you like it and do visit my profile for more blogs. Thanks!

Aneeqa Khan

Software Engineer by profession, Artist by heart

Building Shopping Cart Actions and Reducers with Redux

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Aneeqa Khan