Maintaining Your Data Model › Creating User-Defined Field Types › Specifying Mapping Functions

Specifying Mapping Functions

You can examine and change the value mapping functions in a model using the Edit Functions panel for the *Field attribute types file. This panel shows the mapping functions attached to the field types file.

You can obtain the Edit Functions panel in two ways:

• Type ? for the Ext/int function or the Int/ext function fields on the Edit Field Type panel.

  This will show you a list of functions for the *Field attribute types. Functions can be added on the Edit Functions panel.

• Type F next to a relation of the *Field attribute types on the Edit Database Relations panel.

When you define a function that is based on an access path containing fields of a user-defined field type, CA 2E automatically does the following in the function definition:

• Include fields of the external field type on the device designs of the function.
• Include the field mapping functions at the appropriate points in the action diagrams.
• Pass the internal and external fields to the mapping function parameters.
• Specify that the internal fields are to be used to update the database.

If value mapping is specified for a field type (in other words, Y is specified in the Initial value column of Allow value mapping), both internal/external and external/internal functions must be defined and both must have two parameters. This is to supply and return the internal and external values as appropriate.

If the external/internal function is being used for validation only, only one parameter needs be supplied: the external value.

The order in which you specify the parameters is important. Ensure the following:

• The external version of the field must always be the first parameter, regardless of usage. The field used to define the external parameter should have a field type of NBR, CDE or TXT.
• The field used to define the internal parameter should always be the second parameter. You can specify additional parameters after these two fields.