Showing the message in the cart lets customers see the problem earlier and fix their order before they reach checkout.
Before you start
- Make sure the Nex Validator app embed is enabled in your current Shopify theme — see install.
- Save the theme after enabling the app embed.
Steps
1. Install Nex Validator
If Nex Validator is not installed yet, install it from the Shopify App Store and approve the required permissions. If it is already installed, skip to the next step.
2. Open the rule where you want to show a message in the cart. Turn on Show message in cart page.
3. Make sure the rule is Enabled, then click Save.
4. Add products to the cart so the order does not meet the rule. Open the cart and check that the rule message appears. For example, if the minimum quantity is 2, add only 1 item — the cart should show the message.
When your theme needs a hint
Most Shopify themes should work automatically. If the message does not appear correctly in your cart or cart drawer, your theme may need one of the settings below.
| Setting | Use when |
|---|---|
| Checkout Button Selector | Nex Validator cannot find the checkout button |
| Error Container Selector | You need to choose where the message appears |
| Cart Total Selector | The cart total is not being detected correctly |
| Exclude Selector | An element, such as a Buy Now button, should be ignored |
| Drawer Watch Selector | The message does not appear or update in the cart drawer |
If the cart message already works correctly, leave these settings empty.
Styling it
Use Text Color to change the message color. If you need more design changes, such as the background, border, or spacing, you can use Custom CSS.
Verify it worked
- Create a cart that does not meet the rule → the message should appear in the cart.
- If your store uses a cart drawer, check the message there too.
- Change the cart so it meets the rule → the message should disappear.
- Go to checkout with an invalid cart → the rule should still block checkout.
Cart limits behave slightly differently
Cart quantity and cart amount rules may update differently while customers change items in the cart. Always test the rule at checkout as well to confirm that the limit is working correctly.