Unconditionally calculates a value for the field. Whenever a Derivation expression is evaluated, the current field value is replaced.
Derivation expressions are calculated when the form is first loaded or data is returned from one or more resources
The following example shows a field definition that uses conditional logic to map one set of values into another set. When this field is processed, the expression in the <Derivation> element is evaluated to determine the descriptive value to be displayed for this field based on the location code returned from the resource.
<Field name=’location’> <Display class=’Text’> <Property name=’title’ value=’Location’/> </Display> <Derivation> <switch> <ref>accounts[Oracle].locCode</ref> <case> <s>AUS</s> <s>Austin</s> </case> <s>HOU</s> <s>Houston</s> </case> <case> <s>DAL</s> <s>Dallas</s> </case> <case default=’true’> <s>unknown</s> </case> </switch> </Derivation> </Field>