DMN literal expressions

Some decisions are a calculation rather than a set of rules: a total, a score, a date. Expressing those as a one-row table is awkward, and a literal expression is the intended alternative.

It is a single FEEL expression producing the decision's output.


#What this is for

  • Calculations rather than rule sets.

  • Decisions that combine other decisions arithmetically.

  • Anything you would otherwise write as a table with one row.


#How it works

Action

How

Create

Choose a literal expression as the decision's logic instead of a table.

Write FEEL

One expression, using the decision's inputs by name.

Type

Set the output type reference so downstream decisions know what they receive.

Reference other decisions

By name, as declared in the requirements diagram.


#A few things that catch people out

  • Input names must match the requirements diagram, or the expression cannot resolve them.

  • Keep expressions short. A long one is a table that has not been written yet.

  • Set the output type. Downstream decisions rely on it.



Draw the map before writing the rules.