# Bill of Materials — Kits & Assembly — Full Guide > Overview and requirements The Bill of Materials module adds BOM management to PrestaShop: any product can declare the list of its components with quantities, and the store automatically draws the… - Page: - Language: en - Last updated: 2026-07-08 - Other languages: [fr](https://www.datafirefly.com/documentation/datafireflybom/index.md), [es](https://www.datafirefly.com/es/documentation/datafireflybom/index.md), [de](https://www.datafirefly.com/de/documentation/datafireflybom/index.md), [it](https://www.datafirefly.com/it/documentation/datafireflybom/index.md), [pl](https://www.datafirefly.com/pl/documentation/datafireflybom/index.md), [pt](https://www.datafirefly.com/pt/documentation/datafireflybom/index.md), [nl](https://www.datafirefly.com/nl/documentation/datafireflybom/index.md) - Index: ## Overview and requirements The Bill of Materials module adds **BOM** management to PrestaShop: any product can declare the list of its components with quantities, and the store automatically draws the consequences for stock and price. Two logics are available depending on your business: the **virtual kit** (computed stock, component deduction on sale) and **physical assembly** (manufacturing orders that produce finished product stock). - Compatible with PrestaShop 8.0 to 9.x, Classic theme and derived themes. - PHP 7.4 to 8.3. - Multistore and multilingual. - Components with combinations, multi-level BOMs, circular-reference protection. - PrestaShop-compliant architecture (ModuleAdminController, ObjectModel), no Composer dependency. In **virtual kit** mode, the product's stock is no longer entered manually: the module computes it as the minimum allowed by the components and updates it on every movement. ## Installation Install the module like any PrestaShop module: 1. Download the `datafireflybom.zip` archive from your customer account. 2. In the back office, go to **Modules > Module Manager**. 3. Click **Upload a module** and drop the archive. 4. Once installed, click **Configure** if you want to adjust the global settings. On install, the module creates its tables (`dfbom`, `dfbom_component`, `dfbom_assembly_log`), registers its hooks and adds the **Bills of Materials / BOM** tab under Catalog. BOMs are then managed from each product page. ## Global module settings The configuration page (**Modules > DataFirefly BOM > Configure**) gathers the global settings and the list of existing BOMs: - **Real-time synchronization**: automatically recomputes the stock of virtual kits and computed prices whenever a component's stock or price changes. Enabled by default. - **Allow negative stock**: lets you assemble or sell even if component stock is insufficient (just-in-time). Disabled by default. - **Resync all stocks / prices**: a button that recomputes the stock and price of all active BOMs at once. Useful after an import or data migration. ## Creating a BOM Open a product page, then the **Modules** tab: the **Bill of Materials / BOM** panel appears. Enable the BOM with the switch at the top, then follow the numbered steps. ### 1. Choose the stock mode - **Virtual kit**: the product's stock is computed automatically from the components and every sale deducts them. Ideal for made-to-order boxes and bundles. - **Physical assembly**: the finished product has its own stock, fed by assembly orders. Ideal for batch manufacturing. ### 2. Choose the pricing mode - **Fixed price**: the price stays the one set on the product page. No recalculation. - **Computed price**: the price becomes the sum of the component prices, minus a **percentage discount** you enter. Recomputed automatically when a component's price changes. ### 3. Add the components Use the search field to find a product by name, reference or ID. Results show the thumbnail, reference, stock and price; click to add the component. Each row lets you set the **required quantity** with the +/− buttons. You can add a **specific combination** as a component (it appears separately in the search). The four indicators at the top of the panel (components, buildable quantity, component cost, computed price) update **live** as you adjust quantities and discount, before you even save. ### 4. Save Click **Save the BOM**. The module saves the BOM, immediately recomputes the kit's stock (virtual mode) and applies the computed price if applicable. ## Virtual kit mode In virtual kit mode, the product's stock is the **minimum** its components allow: for a box needing 2 hammers and 1 case, with 120 hammers and 40 cases in stock, the kit shows 40 available units. - On **order validation**, each component's stock is deducted according to the BOM quantities, then the kit's stock — and that of all kits sharing those components — is recomputed. - On **cancellation or refund** of a line, the components are automatically restored. - If **real-time synchronization** is active, any change in a component's stock (direct sale, restock, another kit) updates the stock of the affected kits. Virtual kit mode assumes the kit itself is a product **without combinations**: the computed stock is set on the product (combination 0). Components, however, can be combinations. ## Physical assembly mode In assembly mode, the finished product keeps its own stock. You feed it with **assembly orders** from the product page panel: 1. Enter a quantity (the **Max** button shows how many your component stock allows you to build). 2. Click **Assemble**: the components are consumed and the finished product stock increases. 3. Click **Disassemble** for the reverse operation: the finished product is deducted and the components restored. Every operation is logged in a **history** with employee, date, operation and quantity. The full history is available under **Catalog > Bills of Materials / BOM**. If negative stock is not allowed, assembly is blocked when component stock is insufficient, and disassembly when finished product stock is insufficient. A message shows the maximum possible. ## Computed price In computed price mode, the kit's tax-excluded price equals the sum of its components' tax-excluded prices (multiplied by their quantities), minus the defined percentage discount. This price is written on the product page and recomputed: - each time the BOM is saved; - when a component's price changes, if real-time synchronization is active; - on a global resync from the configuration page. In **fixed price** mode, the module never touches your product page price. The computed price is still shown for reference in the panel, but is not applied. ## Multi-level BOMs and combinations A component can be a **specific combination** of a product (size, color…) or itself a **kit** with its own BOM. Sub-assemblies then nest across multiple levels and stock calculations cascade. The module detects and **blocks circular references**, even indirect ones, at save time: a kit cannot contain itself. ## Storefront composition A checkbox **"Show the Composition tab on the storefront product page"** lets you, per product, present the kit contents to your customers. A **Composition** tab then lists each component with its image, quantity and a link to its page. When disabled, the BOM stays completely invisible on the storefront. ## FAQ and troubleshooting ### The kit's stock doesn't update Check that the BOM is **active**, in **virtual kit** mode, and that real-time synchronization is enabled in the settings. A **Resync all stocks / prices** button on the configuration page forces a full recalculation. ### The computed price isn't applied The price is only written on the product page in **computed price** mode. In fixed price mode, the displayed value is indicative. Also check that the components have a price set. ### I can't assemble Without negative stock allowance, assembly is limited by component stock. The **Max** button shows the maximum possible quantity. Enable **Allow negative stock** in the settings if your workflow requires it. ### A circular reference message appears You are trying to add as a component a product that already contains (directly or through a sub-kit) the product being edited. Remove that component or reorganize your BOM tree. ### Can I sell components separately? Yes, that's the typical scenario. Each component remains a normal product, sellable individually. The module keeps everything consistent: any sale, of the standalone component or the kit, updates the stocks and buildable quantities of all affected kits. ### What happens on uninstall? Uninstalling removes the module's tab and hooks, drops its tables (`dfbom`, `dfbom_component`, `dfbom_assembly_log`) and its configuration variables. Stocks and prices already written on product pages remain as they are.