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Persist cart on refresh #58

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Persist cart on refresh #58

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5a92dfd
fix infinite loop
mattpauls Feb 19, 2023
b5a8c4d
add cart is empty
mattpauls Feb 20, 2023
a048ef6
show cart empty when cart.length is 0
mattpauls Feb 20, 2023
8ddb7ca
load cart from localstorage if exists
mattpauls Feb 22, 2023
bfdffeb
update localstorage cart on add/remove item
mattpauls Feb 22, 2023
6779f11
Merge branch 'developer-job-simulation:main' into persist-cart
mattpauls Mar 11, 2023
a91d835
change updateCart to separate wrap of setCartState
mattpauls Mar 12, 2023
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10 changes: 7 additions & 3 deletions src/Components/Cart.jsx
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import { Dialog, Transition } from "@headlessui/react";
import { XIcon } from "@heroicons/react/outline";
import { XIcon, ShoppingCartIcon } from "@heroicons/react/outline";
import React, { Fragment } from "react";

export default function Cart({ open, setOpen, cart, updateCart }) {
Expand Down Expand Up @@ -37,7 +37,7 @@ export default function Cart({ open, setOpen, cart, updateCart }) {
>
<div className="pointer-events-auto w-screen max-w-md">
<div className="flex h-full flex-col overflow-y-scroll bg-white shadow-xl">
<div className="flex-1 overflow-y-auto py-6 px-4 sm:px-6">
<div className="flex flex-col flex-1 overflow-y-auto py-6 px-4 sm:px-6">
<div className="flex items-start justify-between">
<Dialog.Title className="text-lg font-medium text-gray-900"> Shopping cart </Dialog.Title>
<div className="ml-3 flex h-7 items-center">
Expand All @@ -51,7 +51,11 @@ export default function Cart({ open, setOpen, cart, updateCart }) {
</button>
</div>
</div>

{cart.length == 0 &&
<div className="flex flex-col justify-center items-center flex-1">
<ShoppingCartIcon className="h-12 w-12" />
<span className="pt-2">Your Cart is Empty.</span>
</div>}
<div className="mt-8">
<div className="flow-root">
<ul role="list" className="-my-6 divide-y divide-gray-200">
Expand Down
2 changes: 1 addition & 1 deletion src/Components/ProductTable.jsx
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Expand Up @@ -41,7 +41,7 @@ export default function ProductTable({ cart, updateCart }) {
setProducts(body);
};
fetchProducts();
});
}, []);

return (
<div className="bg-white">
Expand Down
18 changes: 16 additions & 2 deletions src/Pages/Home.jsx
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Original file line number Diff line number Diff line change
@@ -1,11 +1,25 @@
import React, { useState } from "react";
import React, { useEffect, useState } from "react";
import Cart from "../Components/Cart";
import NavBar from "../Components/NavBar";
import ProductTable from "../Components/ProductTable";

function Home() {
const [open, setOpen] = useState(false);
const [cart, updateCart] = useState([]);
const [cart, updateCart] = useState(() => {
const localCart = JSON.parse(localStorage.getItem('cart'))
return localCart ? localCart : []
});

// Trying to have one location to update the local storage when the cart state changes, but only when items are added or removed.
// It doesn't make sense to overwrite the localstorage every time the page is loaded with the logic I have with state, above.
// But this implementation isn't much better, since I'm reading from disk twice on first load, and then again every time the cart is updated.
// The alternative that I'm aware of is to put it in the onClick actions for adding and removing from the cart, which probably makes more sense at this point in time.
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You're on the right track - linking the actions that update the cart to localStorage is what I would recommend, but with a slight twist.

instead of spreading the code to multiple components (as you stated), you can simply wrap the updateCart function in a new function. This new function can update the cart state, and also pass the new cart state straight into localStorage. Here is an example.

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Ohhh I think I see what you did there. That makes sense, I didn't think of handling state within another function. Thank you!

// That way, we're only reading/writing to disk as actually necessary, but it does spread the code to do the same thing across multiple components.
useEffect(() => {
if (cart != JSON.parse(localStorage.getItem('cart'))){
localStorage.setItem('cart', JSON.stringify(cart))
}
}, [cart])

return (
<main>
Expand Down