Fixing Shopify Cart Errors: Tackling JSON Glitches with a Spark of Joy

There’s a particular kind of grin you get when you're knee-deep in coding, and that flamboyant error message prances across your screen. I was working on my Shopify cart page when it happened. The /cart/change endpoint—our fickle companion—decided to fling an invalid JSON error with all the dramatics of a Shakespearean play. For a moment, it felt like staring into the abyss of a broken shopping cart. But like any brave programmer, we dust off our emotional shields and prepare to battle the one-eyed JSON monster.

Grappling with JSON: The Unexpected Culprit

Remember when we used to think the little bugs would stay away as long as we followed the best practices, especially while using trusty old Shopify CLI? Oh, sweet summer child. The error began manifesting when attempting to update item quantities or remove items. Our saga started with the assumption that the Dawn theme was the villain. But no, when developing on localhost, the villain revealed itself: the /cart/change endpoint serving us a half-baked JSON without its closing brackets.

And so, we stood there, bemused, staring at our screen. It reminded me of the time I tried baking a cake during a blackout. The hope was there, but so was the chaos. The missing brackets on items_removed, a small error, were the cause of our digital turmoil.

The Diagnostic Adventure: Unpacking the Mystery

First, let's dive into the errant JSON response. The JSON object with items_removed seemed like a Jackson Pollock painting—beautiful in its chaos, yet utterly confusing. The endpoint responded without closing brackets, leaving our applications scratching their heads.

Why such chaos? Jason (no connection to JSON, but a delightful coincidence) from the Shopify forums pointed out that this usually happens when scripts or links are inadvertently included in the response. Time for Sherlock mode: let's comb through the incoming data.

Opening the cart's CSS and script tags like wrapped gifts on a detangled adventure. It's crucial to ensure there are no tags inserted into the JSON response — trust me, misplaced tags are the dev-world's way of keeping life interesting. Inspect the response using network tools or a debugger for extraneous HTML.

Crafting a Solution: A Dash of Code

Once we identify the issue, we can craft our savior: the code. We need to ensure that the JSON response stays pure and clean like a freshly washed kitten. Here’s a simple way to achieve that:

fetch('/cart/change.js', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    id: variants[0].id,
    quantity: 0,
  }),
})
  .then((response) => response.json())
  .then((data) => {
    if (data.items_removed) {
      // Check if items_removed is an array and validate its structure
      if (
        Array.isArray(data.items_removed) &&
        data.items_removed.every((item) => item && item.id)
      ) {
        console.log('Cart items removed correctly:', data.items_removed)
      } else {
        console.error('Invalid "items_removed" format in JSON:', data.items_removed)
      }
    }
  })
  .catch((error) => console.error('Error updating cart:', error))

Here’s the clever part. The script checks whether items_removed is structured correctly. If you find HTML, clean it out and send a stern look to whoever thought mixing HTML in JSON responses was a good idea.

Wrapping Up the Glitchy Adventure

Wrestling each glitch to submission can feel exhilarating, can't it? Like taming a mustang on the open range—minus the dust and galloping. By ensuring our JSON responses remain pure, our cart changes will execute breezily.

There’s a subtle joy in watching the cart operate perfectly again, knowing we conquered yet another dimensional hiccup in our development journey. And isn’t that the essence of coding? Solving problems, one erroneous JSON bracket at a time, transforming chaos into order, and occasionally, sharing a delightful chuckle with fellow brave souls in the coding trenches.

It’s been a journey filled with twists and turns, but in the end, our cart is more agile, more efficient—and, might I say, sparkling with fresh digital polish. Thanks for joining this adventure with us. Now, let's keep building with a touch of spark and perhaps, just perhaps, fewer unexpected JSONs.