Data Transformation Engine Introduction to the Design Studio

Chapter 4 - Map Designer Map Rules
Introduction to the Design Studio
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Map Rules
A map specifies how to generate a particular output data object, or multiple
independent objects, each of a particular type. Each object on an output card has
a rule cell in which the corresponding map rule is displayed.
Map rules are used to:
♦ Map an input to an output.
♦ Generate desired output, even literal text.
♦ Convert an object in the input data from one value to another value in the
output data.
♦ Perform conditional logic.
♦ Execute another map to produce an output of specific contents.
A map rule must exist for each data object. A map is not complete until each rule
cell has a map rule or appears dimmed (the map rule is unavailable). Empty rule
cells generate a build error when the map is built. A map rule evaluates to a
particular data object (that is either a group type or an item type).
Each map rule begins with an equal sign (=), followed by an expression. A map
rule is an expression that evaluates to data. An expression is any valid
combination of literals, data object names, operators, functions, and map names.
For example, the result of each of the following map rules is data:
= “Florida”
= Price:Input
= COUNT ( Name:Roster )
= RecordMap ( FixedRecord )
Note To generate no data, use a map rule of =NONE.
The expression in a map rule generates the desired data. Functions have their own
syntax. For more information about functions, see the Functions and Expressions
Reference Guide.
Data Evaluation
Map rules are evaluated in sequential order. Each output object with a rule is
created independently from the others.