Now that we've seen how to query existing expressions, this article will take a look at creating new expressions. The code in this article will demonstrate how to create number expressions (unitless), number expressions that reference existing expressions in the formula, string expressions, boolean expressions, integer expressions, point expressions, vector expressions, and list expressions. Also, the code will show how to find and edit existing expressions.

The parts list autoballoon function can be a great time-saver. Unfortunately, it often picks undesirable locations when attaching the leader arrow to the component of interest. The leader locations are easily moved, but when working quickly or on a cramped drawing it can be easy to unintentionally pick the edge of a neighboring component. When the parts list updates, the callouts update and you are left with a component that has no callout.

Expressions are used extensively in NX; they are the parameters of your parametric model. If you write journal code, chances are good that you will need to deal with expressions sooner or later. The code below illustrates how to access all of the expressions in the work part and it shows how to use several key properties and methods of expression objects. When run, the journal will write information about each expression in the current work part to the information window.

The following journal was submitted by user macaber8. The code checks the current work part for the existence of a certain (interpart) expression; if the expression is not found it is created. The code illustrates finding an expression object given a name and creating an interpart expression.

Thank you macaber8 for sharing your code!
-NXJournaling

When working with a parts list on an assembly drawing, it can be difficult to determine if each item in the list has an associated callout balloon on the drawing. NX offers no command to report those items that have missing callouts; the usual course of action is to print a copy of the drawing and manually working through the parts list marking off those items for which you find a balloon. Frank Berger (of GTAC) has recognized this shortcoming and has written a journal that when run will report which items in the list have no corresponding balloon callout.