Define rules between options to prevent invalid configurations.
Constraints are rules that govern which combinations of parameter values are valid. They prevent customers from selecting configurations that cannot be manufactured, shipped, or priced. When a constraint is violated, the configurator shows an inline error message and prevents the customer from proceeding.
A requires constraint means: when parameter A has value X, parameter B must have value Y.
Example: When finish = "outdoor", require material = "aluminum" OR "stainless_steel".
This ensures outdoor products only use weather-resistant materials.
An excludes constraint means: when parameter A has value X, parameter B cannot have value Y.
Example: When material = "glass", exclude size = "XXL".
Glass is not available in the largest size due to shipping limitations.
A conditional range constraint dynamically changes the allowed range of a numeric parameter based on another selection.
Example: When material = "glass", restrict width to 20–80 cm (instead of the default 20–200 cm).
Glass panels have tighter dimensional limits than wood or metal.
An arithmetic constraint validates a math expression across multiple parameters. You write an expression using parameter IDs as variables.
Example: width * height < 10000
The total area (width times height) must not exceed 10,000 square centimeters. This prevents orders that exceed manufacturing capacity.
A count limit constraint restricts how many of a certain type of option can be selected across parameters.
Example: Maximum 2 premium add-ons. If the customer selects “Premium Finish” and “Premium Packaging”, the third premium toggle is disabled.
Useful for subscription tiers, build-your-own bundles, and feature packs.
Combination rules let you forbid or require specific multi-value combinations across multiple parameters at once. Unlike requires/excludes which work between two parameters, combination rules can span three or more.
Example (forbid): The combination color="white" + material="fabric" + use="outdoor" is forbidden.
White fabric is not suitable for outdoor use. Any two of these are fine, but all three together are blocked.
| Type | Logic | Use case |
|---|---|---|
| Requires | If A then must B | Dependencies between options |
| Excludes | If A then cannot B | Incompatible options |
| Conditional Range | If A then B within [min, max] | Dynamic dimensional limits |
| Arithmetic | Expression must be true | Cross-parameter math validation |
| Count Limit | Max N selections of type X | Bundle limits, premium caps |
| Combination | Forbid/require exact combos | Multi-parameter compatibility |
Tip: Start with requires and excludes — they cover 80% of real-world constraint needs. Add arithmetic constraints only for products with dimensional or area limits.