Any model variable can be made into a model parameter. When a variable is made into a model parameter, its value can be specified in the model tool dialog box.
Creating model parameters
- Right-click a variable and click Model Parameter.
On this shortcut menu, a check
appears next to Model Parameter. In the model, a letter P appears beside the variable, indicating it has been made a model parameter.
To designate model variables as parameters so they will be included on the model tool dialog box, the model must be edited in ModelBuilder.
Considerations for creating model parameters
- Only expose as parameters those variables whose values the model user should specify each time the model is run. In the above model, the East Region Clip Feature and West Region Clip Feature variables were not made model parameters since the same dataset is used every time the model is run. There is usually no need to expose every model variable as a parameter.
- If a variable that is exposed as a model parameter does not have a value (the variable is white, or empty), the parameter in the model tool dialog box will be blank. If the variable has a value, it is used as the default value; the parameter will have a value when the model tool dialog box is opened as illustrated above. Although the model illustrated below cannot be run from within ModelBuilder, it can be run from its tool dialog box.
- When a model variable is exposed as a parameter, the variable name becomes the parameter label on the model tool dialog box. If building generic or general use tools with ModelBuilder (tools that will be used by different users with different data), make sure model variable names are clear and easy to understand so the tool dialog parameter labels are also clear and easy to understand.