example.js

import wixData from 'wix-data';

/*
steps:
1. Get the order you need
2. Get a list of images that can be clicked
3. for each image, add a click event
4. In each click event, update the order
   from step 1 to be the id from the image
   
The hardest part will be associating each image
with the item in the collection.
*/

// onReady is called when the page is finished loading.
$w.onReady(async ()=>{
  //       ^^^^^
  // Important! async enables the await keyword.
  // This makes promises not so bad.
  
  const orderId = '---somehow get the order id---'
  
  // get the order before anything else happens.
  const order = await wixData.get('orders', orderId)
  
  const pictures = [
    // You need to get all the picture elements
    // e.g.:
    $w('#picture1'),
    $w('#picture2'),
    ///...
  ]
  
  // note
  // you'll probably need to visually change the picture
  // that is currently selected. You have the pictures in
  // an array, and you have the selected picture in the
  // variable named 'order' (e.g.: order.picture)
  
  pictures.forEach((picture)=>{
    // 'picture' is now set to the actual image on the
    // screen. It is not the item in your collection.
    // You'll need to get the _id of the item somehow.
    picture.onClick = async ()=>{
      // This will not work. Replace 'picture' with the
      // id of the item in the collection.
      order.picture = picture

      await wixData.update('orders', order)
      // note
      // this will not change the page visually. You'll
      // need to add something visually to the image here
      // so it shows the updated selection.
    }
  })
})