For dimensions that contain hierarchy, the refinement dimension object may contain additional information that is useful when displaying refinement values for that dimension.
For ancestors, these calls return a list of dimension values that describe the path from the root of a dimension to the current selection within the dimension:
For example, if a Wineries dimension contained four levels of hierarchy (Country, State, Region, Winery) and the current query was at the region level (Sonoma Valley), the ancestor list would consist of the dimension value United States first and the dimension value California second:
Wineries (root) > United States (ancestor) > California (ancestor) > Sonoma Valley (descriptor)
Refinement dimension values, in this case specific wineries, may still exist for this dimension to refine the query even further. Even though ancestors are normally used to describe selected dimension values, they can also be used to help qualify a list of refinement dimension values. (The refinements are not just wineries, they are United States > California > Sonoma Valley wineries.)
The refinement parent dimension value is accessed with:
These calls return the single dimension value directly above the list of refinements for a given dimension. (In the Ancestors example above, the refinement parent would be Sonoma Valley.)
If no dimension values have already been selected for a given dimension, this refinement parent is the root dimension value (Wineries). If a dimension value has already been selected for a given dimension with hierarchy, this refinement parent is the descriptor dimension value (Sonoma Valley). This single call to retrieve either the root or the descriptor makes creating navigation controls simpler. (There is no need to check whether a hierarchical dimension has already been selected from or not.)
For a flat dimension with no hierarchy, the refinement parent will always be the dimension root, because there would be no further refinements if a value had already been selected for the dimension.
Refinements for a given dimension can only be returned from the MDEX Engine on the same level within the dimension. For example, the MDEX Engine could never return a list of refinement choices that included a mix of countries, states, and regions. (The only exception is flat dimensions that are dynamically organized and/or promoted by the MDEX Engine.)
But in all cases where hierarchy is explicitly defined for a dimension, only refinements on an equal level of hierarchy will be returned for a given query.
