[SOLVED] Redux business logic best practice

Redux business logic best practice

Im building a shopping cart with React and Redux and failing to understand the best practice flow.

My Cart ACTIONS:

export const addToCart = (product) => (dispatch, getState) => {
  let { products: cartProducts } = getState().cart;
  let { newCartProducts, totalPrice } = handleAddToCart(cartProducts, product);
  dispatch(
    add({
      products: newCartProducts,
      total: totalPrice,
    })
  );
};

Mock-Server handlers: (All the logic of updating the product is going here => my main question is if this is makes any sense.

export function handleAddToCart(cartProducts, currentProduct) {
  let idx = cartProducts.findIndex((p) => p.id === currentProduct.id);
  let productInCart = cartProducts[idx];
  if (productInCart) {
    let updatedProduct = {
      ...currentProduct,
      quantity: productInCart.quantity + 1,
      price:
        productInCart.price +
        applySale({
          ...currentProduct,
          quantity: productInCart.quantity + 1,
          currentTotal: productInCart.price,
        }),
    };
    cartProducts.splice(idx, 1, updatedProduct);
  } else cartProducts.push({ ...currentProduct, quantity: 1 });
  let totalPrice = cartProducts.reduce((acc, val) => (acc += val.price), 0);
  return { newCartProducts: cartProducts, totalPrice };
}

Cart reducer:


};
export default (state = DEFAULT_STATE, action) => {
  switch (action.type) {
    case "ADD_TO_CART":
      return {
        products: [...action.payload.products],
        total: action.payload.total,
      };

    default:
      return DEFAULT_STATE;
  }
};

As you see from the code, I kept action and reducer logic to minimum and let the handler manipulate data. only after the data is manipulated, I insert it to the state. After giving it thought, the reducer ADD_TO_CART is only symbolic because it gets an array and not an item so it can be actually a multi purpose reducer which is i think not so good. Would be great to hear more opinions.

Solution