How do we retrieve the category instances matching a search expression?

Question

Consider the following (simplified) example:
We archive consolidated reports. Reports come from different branches each containing the data for multiple departments. We create a category containing attributes for the branch, department, and report date. We apply multiple instances of the category to each report, one for each department contained in the report.
We can specify the department for our search and get back the reports with matching category instances; however, since the report dates are not necessarily predictable we can't qualify the search by date. What we'd like to do is retrieve the matching category instances and display them; the user would then select the desired instance to specify the report for retrieval.
We tried requesting the categories and custom attributes with the search, but it appears ContentDB first finds the qualifying reports then returns all the category instances on those reports--not just the ones that matched the search expression.
I see the SEARCH_FOR_DOCUMENTS, SEARCH_FOR_FOLDERS, etc. search options, but not one for SEARCH_FOR_CATEGORIES (or equivalent). Is there a way to retrieve just the category instances that matched the search expression?

Answer 1

Unfortunately no.
As you have found out, requesting Attributes.CATEGORIES on the document will return all category instances. You would currently need to do client-side processing to locate the specific matching category instance by recursing through the category item[] and checking first that the CATEGORY_CLASS matches, and second, the value of the particular category attribute matches.
If you are building a custom application front-end, maybe you could consider applying a single instance of some master category to the report that has a String array attribute containing all of the associated unique department ids to which the report applies.
Then having applied the 10.1.2.3.1 patchset (and in particular Enh 5171342 NEED SEARCH EXPRESSION SUPPORT FOR ARRAY TYPE CATEGORY ATTRIBUTES), you could quickly locate the reports of interest for a specific department.
The master category instance could also potentially contain an array of DeptID:CategoryInstanceId pairs that allow you to quickly retrieve a specific category instance given a department id.
Matt.