Create and Validate Mask Parameters Using Constraints

A mask contains parameters that take user input from the mask dialog box. You can use parameter constraints to validate these inputs without writing custom code. Constraints verify that the parameter values meet the required conditions.

Validate Mask Parameters Using Constraints

This example shows how to define mask parameter constraints in the Mask Editor and use them to validate user inputs. Parameter constraints are available only for Edit and Combo Box parameters.

Explore Model

The model slexMaskConstraints contains the Subsystem block ConstraintToEditAndComboBoxBlock, whose parameters int8Param1 and int8Param2 must be valid int8 values.

open_system("slexMaskConstraints.slx");

Create and Associate a Parameter Constraint

To create a parameter constraint for the ConstraintToEditAndComboBoxBlock Subsystem block:

1. Create a mask on the ConstraintToEditAndComboBoxBlock block.

2. In the Mask Editor, on the Parameters & Dialog tab, create an Edit parameter named int8Param1 and a Combo Box parameter named int8Param2. For the Combo Box parameter, you must select the Evaluate attribute before associating a constraint.

3. To create a parameter constraint, click the Constraints tab. In the Add Constraints section of Constraint Gallery, double-click Parameter. Specify the Constraint Name as int8Constraint.

4. To specify the properties for the constraint, in the Select Data Types section, select numeric (default). In the Numeric Properties section, clear Any, and select int8.

5. To associate the constraint with the parameter, in the Parameters section of Associations pane, select the parameters int8Param1 and int8Param2. You can also associate a parameter to a constraint on the Parameters & Dialog tab by selecting the constraint in the Constraints list.

Note: The parameter callback code executes after validating the parameter value against the associated constraint. If the validation fails, the callback code does not execute.

Validate the Constraint

Open the mask dialog box, and specify a value outside the int8 range. The software displays an error.

Parameter Constraint Options

The Mask Editor supports four parameter data types — numeric, boolean, enum, and string. The Numeric and enum types include additional properties that you can use to define and validate constraints.

Data Type	Property Name	Property Values	Description
numeric	Data Types	Any, double, single, half, int8, uint8, int16, uint16, int32, uint32, int64, uint64	Specify the acceptable data type of the mask parameter value. You can choose multiple data types.
	Complexity	real, complex	Specify whether the mask parameter value is a real or complex number.
	Dimension	scalar, row vector, column vector, 2-D matrix, n-D matrix	Specify the acceptable dimensions for the mask parameter.
	Sign	positive, negative, zero	Specify if the input value must be positive, negative, or zero.
	Finiteness	finite, inf, -inf, NaN	Specify the acceptable finiteness of the mask parameter value.
	Fraction	integer, decimal	Specify if the input value must be an integer or decimal.
	Range	Minimum, Maximum	Specify the acceptable range of mask parameter value.
enum	Class Name	Valid Simulink enum name	Specify the enum class name.

Note

To validate the parameter value against a specific range, use the Minimum and Maximum properties, because the Data Types property does not validate the parameter value against the range. For example, to validate the parameter value against the data type numeric and range 0 to 127, set Data Types to numeric, Minimum to 0 and Maximum to 127.

The Custom Rule section, which contains MATLAB Expression and Error Message options, is available for all data types and lets you define additional validation logic for any parameter.

Property Name	Property Value	Description
MATLAB Expression	Valid MATLAB expression	Specify a custom constraint for the mask parameter using a valid MATLAB expression that returns a Boolean value. You can use the value token to parameterize the expression. During validation, the evaluated value of the parameter replaces the value token.
Error Message	Character vector	Specify a custom error message for the custom constraint. You can specify the error message as character vector or as a message catalog ID.