Constraints

Constraints enforce rules and conditions on types, variables, and relationships. Use constraints to define logical restrictions and ensure consistency within the model.

Every variable in a configuration carries a cfgStatus value that records how its current value was set. The constraint engine uses cfgStatus to decide whether it can change a variable’s value while solving. A variable’s cfgStatus is one of these values.

User A user manually set the value during configuration. The constraint engine treats this value as fixed.
Default A setDefault or preference rule set the value. The constraint engine can override this value while solving.
Engine The constraint engine set the value to satisfy a constraint.

Constraints skip any variable whose cfgStatus is User. As a result, a constraint that would otherwise change the variable has no effect on a user-set value. To enforce a value regardless of user input, make sure no user-set value conflicts with the constraint.

In some conditions, the constraint engine can override a value set by a user. If this happens, contact Salesforce Customer Support.

Note

For more information about the supported constraints, see:

Supported Logic Operators

These logic operators are supported in CML.

Arithmetic Operators

Multiplication (*)
Division (/)
Remainder (%)
Addition (+)
Subtraction (-)

Relational Operators

Greater than (>)
Greater than or equal to (>=)
Less than (<)
Less than or equal to (<=)

Equality Operators

Equal (==)
Not equal (!=)

Logic Operators

Not (!)
And (&&)
XOR/Exclusive or (^)
Or (||)
Bi-conditional (<->)
Conditional (?:)
Implication (->)

Operator Precedence

In resolving equations, operator precedence determines the order in which operations are performed. Operators in CML have precedence in this order:

Arithmetic operators have the first precedence.
Relational operators have the second precedence.
Equality operators have the third precedence.
Logic operators have a lower precedence than equality operators, in decreasing order as listed, with Implication having the lowest precedence.

Constraint Annotation

Here are the details of abort, a constraint annotation.

Annotation	Possible Values	Description
abort	true, false	Specifies that, if this constraint fails, abort search and return `false` for configuration.

Logical Constraints

A logical constraint defines a statement that must hold true logically. The constraint can be any logical expression by using a logical operator.
Table Constraints

The table constraint in Constraint Modeling Language (CML) is used to define a set of valid combinations of values for two or more attributes. These combinations are specified in rows within the constraint definition.
Proxy Variables with Constraints on Types and Relationships

Use proxy variables to reference the variables of related types, including parent, root, and sibling types.
Message Rule

The message rule displays a message to users based on specified conditions.
Preference Rule

The preference rule encourages the constraint solver to satisfy the condition, but doesn’t enforce it if the condition can’t be met.
Require Rule

The require rule requires certain components to be included in a relationship when specified conditions are met.
Require Rule vs Constraint

In Constraint Modeling Language (CML), constraint() and require() can both enforce behavior, but they operate differently: constraint focuses on logical consistency, require focuses on physical presence of products.
Setdefault Rule

The setdefault rule allows component selection with attribute values and quantity, similar to the require rule.
Exclude Rule

The exclude rule automatically removes a specific type in a relationship if a certain condition is true.
Action Rule

The CML Action Rule is defined using the rule() keyword. Its primary purpose is to execute a designated action, specified as a string literal, when a condition is met.
Hide or Disable Rule

The Hide or Disable Rule uses the rule() keyword to conditionally remove an element from the selection menu (hide) or preserve it in the menu while preventing user selection (disable).
Recommendation Rule

The recommend keyword is used within a Constraint Modeling Language (CML) rule to display suggestions for related products in the Product Configurator. The rule defines the condition under which a specific product type or relation should be suggested to the user.
Set Product Selling Model in a Constraint

Use the productSellingModel tagname to write a constraint that sets the Product Selling Model (PSM) for a type. You can define a PSM as one time, time-deferred (subscription with end date), or evergreen (recurring subscription with no preset end date). The PSM is updated for new line items at runtime, based on the constraint.