I’m working on the front end of a restaurant takeaway system, and I need to create an “infinitely” recursive nested product form wizard similar to the UberEats modal product form flow. The form should display product modifiers (via modifier groups) and have specific rules.
Here’s a simplified structure of the product data returned by our API:
Product Types:
type: 1= Main Producttype: 3= Modifier Group (e.g., size, crust type)type: 2= Modifier (e.g., specific size, specific crust)
Rules:
min= Minimum quantity for a modifiermax= Maximum quantity for a modifiermulti_max= Maximum times the same modifier can be chosen
For instance, a “Pizza” product might have a “Pizza Size” modifier group with modifiers like “9 inch” and “12 inch.” If “12 inch” is selected, further modifiers like “Stuffed Crust” or “Thin Crust” might appear via the nested “12 inch pizza crust” modifier group , with specific rules applied.
How can I dynamically display and hide these groups and modifiers based on the users selections, ensuring that only relevant sub-products and modifier groups appear when needed, while also enforcing the min, max, and multi_max modifier group rules for the modifiers? The products sub-products can vary in depth, so the solution needs to be flexible / “infinite”.
Below is an example of what I’ve tried so far, using JSON data for a pizza product. It somewhat works in terms of a flow but I’ve hit a kind of coder’s block. I’m not sure if my approach is correct, I am getting console errors and I’m also not sure how I advance what I’ve written so far to work with the rules and how to later submit it back to the API as form data.
Note: I’m using AlpineJS.
<code><!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" />
</head>
<body class="d-flex flex-column h-100 font-sans antialiased fs-7">
<main class="flex-shrink-0">
<div x-data="getProduct()">
<h1 x-text="product.name"></h1>
<div x-data="{
currentProduct: product,
}">
<div x-data="{
currentStep: 1,
totalSteps: currentProduct.sub_products.length
}">
<div class="row" x-init="$watch('currentProduct', value => {
totalSteps = value.sub_products.length;
key++; // Increment key to force re-render
})">
<div class="col-12 mb-2">
<h4 x-text="currentProduct.name"></h4>
Steps: <span x-text="totalSteps"></span>
Current Step: <span x-text="currentStep"></span>
</div>
<div class="col-12 mb-2">
<nav class="nav nav-pills flex-column flex-sm-row gap-1">
<template x-for="(sub_product, index) in currentProduct.sub_products">
<button
type="button"
class="flex-sm-fill text-sm-center nav-link border"
:class="{ 'active': currentStep === index+1 }"
@click.prevent="currentStep = index+1"
>
<span x-text="sub_product.name"></span>
</button>
</template>
</nav>
</div>
<div class="col-12">
<!-- Back Button -->
<button x-show="trail.length > 0" @click="
let lastStep = trail.pop();
currentProduct = lastStep.product;
currentStep = lastStep.step;
" class="btn btn-warning mb-2">
Back
</button>
<!-- Tab panes -->
<div>
<template x-for="(sub_product, index) in currentProduct.sub_products" :key="key + '-' + index">
<div
x-show="currentStep === index+1"
>
<div class="border rounded bg-light p-2">
<div class="d-flex justify-content-between mb-2">
<div>
<h5 class="mb-0"><span x-text="sub_product.name"></span></h5>
</div>
</div>
<ul class="list-group list-group-flush mb-0">
<template x-for="(deep_sub_product, index) in sub_product.sub_products" :key="key + '-' + deep_sub_product.id">
<li class="list-group-item d-flex justify-content-between align-items-center py-3">
<label class="stretched-link" x-bind:for="deep_sub_product.id"><span x-text="deep_sub_product.name"></span></label>
<input @change="
let isChecked = $event.target.checked;
if(isChecked) {
if(deep_sub_product.sub_products && deep_sub_product.sub_products.length) {
trail.push({ product: currentProduct, step: currentStep });
currentProduct = deep_sub_product;
currentStep = 1;
}
}"
class="form-check-input ms-1" type="checkbox" value="" x-bind:id="deep_sub_product.id">
</li>
</template>
</ul>
</div>
</div>
</template>
</div>
</div>
</div>
</div>
</div>
</div>
<script type="text/javascript">
function getProduct() {
return {
product: {
"id": "01j51xtwmcm4bmz2jpd2x8d1j0",
"type": 1,
"name": "Pizza",
"plu": "PROD-PIZ-IVUAW",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "500",
"currency": "GBP",
"formatted": "£5.00"
},
"sub_products": [
{
"id": "01j51xw86mj4zpw71qzd23yxkt",
"type": 3,
"name": "Pizza Size",
"plu": "MG-PIZ-GKNDC",
"min": 1,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51xxbrqyj6v0bs71503pvhz",
"type": 2,
"name": "9 inch",
"plu": "MOD-9IN-4O5B2",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "0",
"currency": "GBP",
"formatted": "£0.00"
},
"sub_products": []
},
{
"id": "01j51xxx0vaejrdnx80e2sc44m",
"type": 2,
"name": "12 inch",
"plu": "MOD-12I-LGK4P",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "200",
"currency": "GBP",
"formatted": "£2.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust DEPTH TEST",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust DEPTH TEST",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": []
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust DEPTH TEST",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
}
]
},
{
"id": "01j51zcdww6ekes424wse5w689",
"type": 3,
"name": "Pizza Additional Toppings",
"plu": "MG-PIZ-3VQTI",
"min": null,
"max": 3,
"multi_max": 3,
"sub_products": [
{
"id": "01j51zap82spt05ysm3m2fj9t4",
"type": 2,
"name": "Pepperoni",
"plu": "MOD-PEP-HDPL0",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zb90ptzkb7d5w92sphx1g",
"type": 2,
"name": "Pineapple",
"plu": "MOD-PIN-K7ZEV",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zbrajdmx0hz4136e41n8p",
"type": 2,
"name": "Tomato",
"plu": "MOD-TOM-ERSMC",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
trail: [],
key: 0
}
}
</script>
</main>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cdn.min.js"></script>
</body>
</html></code>
<code><!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" />
</head>
<body class="d-flex flex-column h-100 font-sans antialiased fs-7">
<main class="flex-shrink-0">
<div x-data="getProduct()">
<h1 x-text="product.name"></h1>
<div x-data="{
currentProduct: product,
}">
<div x-data="{
currentStep: 1,
totalSteps: currentProduct.sub_products.length
}">
<div class="row" x-init="$watch('currentProduct', value => {
totalSteps = value.sub_products.length;
key++; // Increment key to force re-render
})">
<div class="col-12 mb-2">
<h4 x-text="currentProduct.name"></h4>
Steps: <span x-text="totalSteps"></span>
Current Step: <span x-text="currentStep"></span>
</div>
<div class="col-12 mb-2">
<nav class="nav nav-pills flex-column flex-sm-row gap-1">
<template x-for="(sub_product, index) in currentProduct.sub_products">
<button
type="button"
class="flex-sm-fill text-sm-center nav-link border"
:class="{ 'active': currentStep === index+1 }"
@click.prevent="currentStep = index+1"
>
<span x-text="sub_product.name"></span>
</button>
</template>
</nav>
</div>
<div class="col-12">
<!-- Back Button -->
<button x-show="trail.length > 0" @click="
let lastStep = trail.pop();
currentProduct = lastStep.product;
currentStep = lastStep.step;
" class="btn btn-warning mb-2">
Back
</button>
<!-- Tab panes -->
<div>
<template x-for="(sub_product, index) in currentProduct.sub_products" :key="key + '-' + index">
<div
x-show="currentStep === index+1"
>
<div class="border rounded bg-light p-2">
<div class="d-flex justify-content-between mb-2">
<div>
<h5 class="mb-0"><span x-text="sub_product.name"></span></h5>
</div>
</div>
<ul class="list-group list-group-flush mb-0">
<template x-for="(deep_sub_product, index) in sub_product.sub_products" :key="key + '-' + deep_sub_product.id">
<li class="list-group-item d-flex justify-content-between align-items-center py-3">
<label class="stretched-link" x-bind:for="deep_sub_product.id"><span x-text="deep_sub_product.name"></span></label>
<input @change="
let isChecked = $event.target.checked;
if(isChecked) {
if(deep_sub_product.sub_products && deep_sub_product.sub_products.length) {
trail.push({ product: currentProduct, step: currentStep });
currentProduct = deep_sub_product;
currentStep = 1;
}
}"
class="form-check-input ms-1" type="checkbox" value="" x-bind:id="deep_sub_product.id">
</li>
</template>
</ul>
</div>
</div>
</template>
</div>
</div>
</div>
</div>
</div>
</div>
<script type="text/javascript">
function getProduct() {
return {
product: {
"id": "01j51xtwmcm4bmz2jpd2x8d1j0",
"type": 1,
"name": "Pizza",
"plu": "PROD-PIZ-IVUAW",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "500",
"currency": "GBP",
"formatted": "£5.00"
},
"sub_products": [
{
"id": "01j51xw86mj4zpw71qzd23yxkt",
"type": 3,
"name": "Pizza Size",
"plu": "MG-PIZ-GKNDC",
"min": 1,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51xxbrqyj6v0bs71503pvhz",
"type": 2,
"name": "9 inch",
"plu": "MOD-9IN-4O5B2",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "0",
"currency": "GBP",
"formatted": "£0.00"
},
"sub_products": []
},
{
"id": "01j51xxx0vaejrdnx80e2sc44m",
"type": 2,
"name": "12 inch",
"plu": "MOD-12I-LGK4P",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "200",
"currency": "GBP",
"formatted": "£2.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust DEPTH TEST",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust DEPTH TEST",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": []
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust DEPTH TEST",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
}
]
},
{
"id": "01j51zcdww6ekes424wse5w689",
"type": 3,
"name": "Pizza Additional Toppings",
"plu": "MG-PIZ-3VQTI",
"min": null,
"max": 3,
"multi_max": 3,
"sub_products": [
{
"id": "01j51zap82spt05ysm3m2fj9t4",
"type": 2,
"name": "Pepperoni",
"plu": "MOD-PEP-HDPL0",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zb90ptzkb7d5w92sphx1g",
"type": 2,
"name": "Pineapple",
"plu": "MOD-PIN-K7ZEV",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zbrajdmx0hz4136e41n8p",
"type": 2,
"name": "Tomato",
"plu": "MOD-TOM-ERSMC",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
trail: [],
key: 0
}
}
</script>
</main>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cdn.min.js"></script>
</body>
</html></code>
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.jsdelivr.net/npm/[email protected]/dist/css/bootstrap.min.css" rel="stylesheet" />
</head>
<body class="d-flex flex-column h-100 font-sans antialiased fs-7">
<main class="flex-shrink-0">
<div x-data="getProduct()">
<h1 x-text="product.name"></h1>
<div x-data="{
currentProduct: product,
}">
<div x-data="{
currentStep: 1,
totalSteps: currentProduct.sub_products.length
}">
<div class="row" x-init="$watch('currentProduct', value => {
totalSteps = value.sub_products.length;
key++; // Increment key to force re-render
})">
<div class="col-12 mb-2">
<h4 x-text="currentProduct.name"></h4>
Steps: <span x-text="totalSteps"></span>
Current Step: <span x-text="currentStep"></span>
</div>
<div class="col-12 mb-2">
<nav class="nav nav-pills flex-column flex-sm-row gap-1">
<template x-for="(sub_product, index) in currentProduct.sub_products">
<button
type="button"
class="flex-sm-fill text-sm-center nav-link border"
:class="{ 'active': currentStep === index+1 }"
@click.prevent="currentStep = index+1"
>
<span x-text="sub_product.name"></span>
</button>
</template>
</nav>
</div>
<div class="col-12">
<!-- Back Button -->
<button x-show="trail.length > 0" @click="
let lastStep = trail.pop();
currentProduct = lastStep.product;
currentStep = lastStep.step;
" class="btn btn-warning mb-2">
Back
</button>
<!-- Tab panes -->
<div>
<template x-for="(sub_product, index) in currentProduct.sub_products" :key="key + '-' + index">
<div
x-show="currentStep === index+1"
>
<div class="border rounded bg-light p-2">
<div class="d-flex justify-content-between mb-2">
<div>
<h5 class="mb-0"><span x-text="sub_product.name"></span></h5>
</div>
</div>
<ul class="list-group list-group-flush mb-0">
<template x-for="(deep_sub_product, index) in sub_product.sub_products" :key="key + '-' + deep_sub_product.id">
<li class="list-group-item d-flex justify-content-between align-items-center py-3">
<label class="stretched-link" x-bind:for="deep_sub_product.id"><span x-text="deep_sub_product.name"></span></label>
<input @change="
let isChecked = $event.target.checked;
if(isChecked) {
if(deep_sub_product.sub_products && deep_sub_product.sub_products.length) {
trail.push({ product: currentProduct, step: currentStep });
currentProduct = deep_sub_product;
currentStep = 1;
}
}"
class="form-check-input ms-1" type="checkbox" value="" x-bind:id="deep_sub_product.id">
</li>
</template>
</ul>
</div>
</div>
</template>
</div>
</div>
</div>
</div>
</div>
</div>
<script type="text/javascript">
function getProduct() {
return {
product: {
"id": "01j51xtwmcm4bmz2jpd2x8d1j0",
"type": 1,
"name": "Pizza",
"plu": "PROD-PIZ-IVUAW",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "500",
"currency": "GBP",
"formatted": "£5.00"
},
"sub_products": [
{
"id": "01j51xw86mj4zpw71qzd23yxkt",
"type": 3,
"name": "Pizza Size",
"plu": "MG-PIZ-GKNDC",
"min": 1,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51xxbrqyj6v0bs71503pvhz",
"type": 2,
"name": "9 inch",
"plu": "MOD-9IN-4O5B2",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "0",
"currency": "GBP",
"formatted": "£0.00"
},
"sub_products": []
},
{
"id": "01j51xxx0vaejrdnx80e2sc44m",
"type": 2,
"name": "12 inch",
"plu": "MOD-12I-LGK4P",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "200",
"currency": "GBP",
"formatted": "£2.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": [
{
"id": "01j51xz2qhze0synfzwbg8qkyp",
"type": 3,
"name": "12 inch pizza crust DEPTH TEST",
"plu": "MG-12I-PTYOS",
"min": null,
"max": 1,
"multi_max": null,
"sub_products": [
{
"id": "01j51y0n1dfa1eech6rc4avx5f",
"type": 2,
"name": "Stuffed Crust DEPTH TEST",
"plu": "MOD-STU-9H2BP",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "100",
"currency": "GBP",
"formatted": "£1.00"
},
"sub_products": []
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust DEPTH TEST",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
{
"id": "01j51y1crn99gg2evy2b96ytev",
"type": 2,
"name": "Thin Crust",
"plu": "MOD-THI-0TYVD",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
}
]
},
{
"id": "01j51zcdww6ekes424wse5w689",
"type": 3,
"name": "Pizza Additional Toppings",
"plu": "MG-PIZ-3VQTI",
"min": null,
"max": 3,
"multi_max": 3,
"sub_products": [
{
"id": "01j51zap82spt05ysm3m2fj9t4",
"type": 2,
"name": "Pepperoni",
"plu": "MOD-PEP-HDPL0",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zb90ptzkb7d5w92sphx1g",
"type": 2,
"name": "Pineapple",
"plu": "MOD-PIN-K7ZEV",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
},
{
"id": "01j51zbrajdmx0hz4136e41n8p",
"type": 2,
"name": "Tomato",
"plu": "MOD-TOM-ERSMC",
"min": null,
"max": null,
"multi_max": null,
"price": {
"amount": "50",
"currency": "GBP",
"formatted": "£0.50"
},
"sub_products": []
}
]
}
]
},
trail: [],
key: 0
}
}
</script>
</main>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cdn.min.js"></script>
</body>
</html>Example of an UberEats Pizza product, to somewhat visualise what I’m trying to achieve:
PS: Sorry if the code is messy, I’ve been tweaking this trying to figure it out for weeks now!