Option Combinations for OpenCart — stock, price and SKU of every option combination

Option Combinations for OpenCart counts not separate option values but their combinations. A “red × M” T-shirt has its own stock, “blue × L” has its own, and “green × S” is not sold at all. Plain OpenCart cannot do that: stock and surcharges exist only per value, so the shop keeps selling “red M” after red M is gone, as long as there are some red ones and some M ones.

The module gives a product a combination grid built from “select” and “radio” options. Every combination has its availability and stock, and in Pro a surcharge, weight, its own SKU and photo. On the product page unavailable combinations are greyed out, conditional options show up only when needed (“engraving text” only after “Engraving: yes”), and drop-downs become colour dots and buttons. No OpenCart core file is changed. One licence, three builds: OpenCart 4.x, 3.x and 2.3.

What the customer sees

• What is there is visible. A value no combination is sold with is greyed out and cannot be clicked. A value that only conflicts with the current pick (blue exists, just not in S) is dimmed — clicking it clears the conflicting pick instead of showing an error.
• The variant price at once. The page asks the shop for the price of the picked combination — the one the cart will charge, with specials, discounts and tax — and puts it into the theme price together with the “Ex Tax” line.
• SKU, availability, photo. Under the options — SKU and availability of the combination (or the exact quantity, if you choose so), and the combination photo replaces the main one.
• Nothing extra. A conditional option stays hidden until needed and is not required while hidden.

What the admin gets

Extensions → Modules → Option Combinations, four tabs: Products, Swatches, Settings and Licence.

• A grid in a minute. Pick a product, tick the options the variants are made of and press “Add missing combinations” — the module creates every combination and leaves existing rows as they are. Bulk changes for all rows — one line above the grid.
• Product policy: what to do with a combination missing from the grid (do not sell, or sell as an ordinary product) and with a sold-out one (grey it out, hide it or take backorders).
• Conditional options: “show option B when A has one of the ticked values”, chains of conditions; a condition that loops back on itself is not saved.
• Checks before saving: a non-numeric stock, a negative surcharge without a sign, a photo outside the shop folders — the module names the combination with the mistake and saves nothing.
• Per-value stock of the grid options is switched off by the module itself, and it says how many values it switched off.

Pro: surcharge, weight, SKU and photo of every combination

• Surcharge with a + or − sign on top of the product price and other options; specials and taxes work as always.
• Weight of the combination — for shipping that counts weight.
• SKU of the combination becomes the model of the order line: it shows in the cart, the order, the invoice and the waybill.
• Photo — one of the product photos, replaces the main one on the page and in the cart.
• No cap on products.

How it works, step by step

1. You build the grid in the admin: product, options, stock, and in Pro prices, SKUs and photos.
2. On the product page the module hands the grid to a script that draws swatches, greyed-out values and conditional options over the ordinary OpenCart form — the pick goes to the cart through the same fields.
3. On “add to cart” the module checks the combination and the stock and answers with OpenCart’s own option error when it cannot be sold.
4. The cart is built with OpenCart’s own cart class a second time, and lines with a combination get its surcharge, weight, SKU, photo and stock. Everything else is counted by OpenCart itself, so the cart, the mini-cart, the checkout and One Page Checkout show the same amounts.
5. When an order enters a processing or complete status, the module takes the combination stock (once per line) and returns it when the order leaves those statuses.

Under the hood

• No core edits. OpenCart events and a startup action (on 3.x and 2.3 — an event before the first controller). Core files and option prices in the catalogue are not changed.
• Own tables: product settings, combinations, conditions, swatch looks, value colours and a journal of stock taken per order line (so a cancellation returns exactly what was taken).
• Compatibility. Option Specials builds its cart under ours, so a special on a value and the combination surcharge apply together; Size Price Calculator wraps our cart whichever of the modules starts first.
• Load. Products without a grid are not touched; with a grid the cart is counted by OpenCart’s class once more — unnoticeable on a normal cart.
• Feeds see the product as before — there is no separate integration with combinations.
• Multi-store: grids and swatches are shared by all stores of one installation.
• Removal. The uninstall removes the events and the startup row and drops the module tables unless “Keep the data when the module is uninstalled” is on in the settings. On OpenCart 2.3 the settings go too, the licence key with them — activate it again after a reinstall.

How to install

1. OpenCart 4: Extensions → Installer → upload cc_optcomb.ocmod.zip (do not rename the archive) and press Install. OpenCart 3: Extensions → Installer → cc_optcomb-oc3.ocmod.zip, then Extensions → Modifications → Refresh. OpenCart 2.3: the 2.3 installer copies nothing without a configured FTP, so upload the contents of the upload/ folder from cc_optcomb-oc2.ocmod.zip to the shop root through your hosting file manager — no FTP setup in OpenCart needed.
2. Extensions → Extensions → Modules → Option Combinations → Install, then Edit.
3. Settings tab: Status on; optionally how to show stock and whether to swap the photo. Save.
4. Products tab: pick a product, tick the grid options, press “Add missing combinations”, fill in the stock and press “Save product”.
5. Swatches tab: for “Colour” choose “colours” and a colour per value, for “Size” — “buttons”.
6. For Pro: paste the licence key from the e-mail after payment or start the 7-day trial on the Licence tab.