[CONNECT] Item Types Lookup Table

Hi Jon,

Jon Summers said:

Is there any API for Item Type property lookup tables?

I have not found anything where ItemTypes lookup tables are mentioned, but...

Jon Summers said:

Is CustomProperty.DefaultValueExpression related to this or does that do something else?

I did not write any test code, but it looks like a right method that should be tested first.

It's known I prefer to use pure EC approach, at least to understand using what EC features ItemTypes are implemented. I did some quick tests that confirms my former findings:

• ItemType property's features are internally implemented using EC Custom attributes that allows to modify a behaviour of EC Classes and EC Properties.
• Pick list definition is represented by ItemTypePickListName attribute (plus ExtendType is used also, but a function of this attribute is not explained anywhere).
• Lookup table expression is represented by CalculatedECPropertySpecification attribute.
• Default value is also represented by CalculatedECPropertySpecification attribute.

My assumption is that:

• CustomProperty.DefaultValue allows to define the property default value, which is just one const value.
• CustomProperty.DefaultValueExpression allows to define ECExpression (not only LookUp.GetEntry expression). I am not sure how required symbol sets are defined in this case, maybe fixed predefined sets are configured automatically.

If I am wrong, look up method definition can be easily added to existing EC property using CalculatedECProperty.

With regards,

  Jan

Hi Jon,

In Update 14 SetExpression() API is introduced for setting up Expression values on CustomProperty class.

For the usage details you can refer following link :

https://communities.bentley.com/products/programming/microstation_programming/b/weblog/posts/working-with-itemtype-ec-expression-using-managed-native-and-com-api-s-upcoming-feature-in-microstation-connect-edition-update-14