System.NullReferenceException:“Object reference not set to an instance of an object.” applicationContext is null。

[qhliao66]

Describe the bug
Main object "order", "order" sub object "OrderItems". Binding "OrderItems" to "grid control", there was an error in automatically adding rows using the grid.

Version and Platform
CSLA version: 6.0
OS: Windows
Platform: WinForms

[rockfordlhotka]

What is the code that calls GetFormatter?

[qhliao66]

[qhliao66]

In this example, the error is the same. The reason seems to be that the "ApplicationContext" of the current object has not been assigned after the object is created.

In this example, move the mouse over the grid addition row, and an error occurs.

WinFormsApp1.zip

[rockfordlhotka]

Is it possible that the business object instance was created using the new keyword instead of using the data portal?

In CSLA 6 you can't use the new keyword or Activator.CreateInstance, because every object must have a reference to the application context, which is set via the IUseApplicationContext interface. The data portal, and ApplicationContext.CreateInstance methods do this correctly.

[qhliao66]

A collection of grid bound data objects. When adding rows to the grid, sub objects are automatically created by the grid. The grid was not created by calling "data portal".

The code in the "red box" is added to correct this error. Is this appropriate?

[rockfordlhotka]

That seems reasonable.

I well-behaved data grid control will use the collection's data binding interface to request adding a new item, and that allows you to (in your collection class) override the add new child method so you can create the new child properly.

Some controls don't do that correctly (shame on them!), so your workaround seems reasonable.

[qhliao66]

@rockfordlhotka Thank you very much!

[TanguyIngels]

Will the suggested fix be applied in the framework? Because I've the same issue with version 6.2.0.

[rockfordlhotka]

Tracking issue: #3141