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DEVELOPERS FORUM - Can pls explain polyitem concept in ARAS.

m.babu - Thursday, January 22, 2015 5:31 AM:



Can pls explain polyitem concept in ARAS. what is advantage and disadvantage of defining a type as polyitem.

Eric Domke - Friday, February 20, 2015 8:13 AM:

Just as an item type is equivalent to a table in SQL, a polyitem is equivalent to a view in SQL.  In particular, a polyitem view is a special view which is essentially a union of the select statements for several tables (i.e. item types).  Polyitems allow you to build relationships without restricting the relationship to only a particular item type.  In particular, if you want a relationship which would allow you to add a document, CAD document, or part, you would build a polyitem with those item types.  You would then create a relationship to that polyitem.  The main disadvantage of polyitems is that they can only return properties that are named the same across all the item types.  For example, if you want to include description information for the two item types you included, but in one item type the property is called "descrip" and in the other it is called "description", you can't include that property in the polyitem.