Creating undo marks and forcing model updates

This section explains how to manage the model data from the application program. Undo processing and model updates are used to either roll back or lock in changes to the model made by your application. Although there is nothing unique about undo processing or model updates in NX Open for CAE applications, you need to understand these concepts to successfully create CAE applications.

Creating an undo mark

The undo function creates an undo mark. In the event of an error, you can revert to this undo mark.

The undo methods ensure that the session and parts are returned to a valid state. To use the undo methods, you first create an undo mark. This saves the current state of the software.

• If the program executes without error, then you can call the method to delete the undo mark (unless the undo mark is visible and is being provided to let the user undo the operations of the custom application).

• If the program encounters an error and needs to recover, you can revert to the undo mark.

Any undo mark that is created during the course of running a Block Styler application will be removed by the OK and Apply call backs, which impose their own undo mark encompassing the entire application.

For more information on undo marks, see the NX Open Programmers Guide → Handling Errors → Undo.

Forcing a model update

The Model Update function forces a model to update. Most NX Open methods that modify the internal data model perform a Model Update before they return to the calling application. A few methods are designed to be executed multiple times without Model Update. These methods require you to explicitly invoke a Model Update when the set of operations are complete. The NX Open API documentation lists which classes and methods require you to explicitly invoke the Model Update function.

Use the following command to invoke the Model Update function:

Python

theSession.UpdateManager.DoUpdate(undoMark)

VB.NET

theSession.UpdateManager.DoUpdate(undoMark As NXOpen.Session.UndoMarkID)

If the software encounters an error during the DoUpdate() method, the system will roll back to the undo mark specified in the call to the update manager.

For more information on the Model Update function, see the NX Open Programmers Guide → Other NX Operations → Model Update.

Learn more

NX Open for CAE terminology and concepts

CAD terminology and concepts

CAE terminology and concepts

The importance of the work part in CAE applications

Overview of the CAE data model

Working with objects in the CAE data model

Overview of the CAE solver languages

Working with the CAE solver languages: name strings

Working with the CAE solver languages: property tables

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NX Open for CAE documentation resources

NX Open for CAE code examples

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Creating undo marks and forcing model updates, Simcenter 3D 2021.1 Series

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