3 Replies Latest reply on Nov 11, 2014 8:14 AM by Roger Palmen

    Pi Web API Search: why no WebIDs included of attributes?

    Roger Palmen

      I'm looking for a way to use the PI Web API to build a (web) Portal. For that portal, one of the types of things that are needed is one KPI for each Asset. Assets, about 400 of them, are down 3 levels from the AF root.


      I expected to resolve this using a query like this:


       But the unexpected return is that i get a list of all Elements that contain an attribute containing "KPI", all attributes of all those elements, and the WebID of the Element. Not only i now get hundreds of attributes which i did not ask for, i also don't get the WebID of the attributes! So i still need to make 400 calls to request the WebIDs of attribute of the elements. I'd expected a similar return as the GET elements/{webId}/attributes call, which does include the WebIDs of the attributes.


      So my basic questions: If the search allows searching for attributes, why not return the WebID's of the attributes?


      Some other observations:

      • why not restrict to the queried attributenames? It's now not "search" but "elementsearch"
      • why do i get all attributes of the attributes and not only the requested fields?
      • why are different names used in different sections of the query? E.g. "afelementtemplate" in the q section, but "template" in the fields section
      • the documentation is missing a list of fields to use in each section (q / fields0. It's now just the fields in the help? Or guesswork?
      • documentation is a bit sparse on the search topic...

      So the only option i see: is to wait for the ODATA supporting batch calls, or bulk calls support in general. The only way to get WebIDs of attributes is by using the GET attributes call, e.g on path or getting all attributes for the element.

        • Re: Pi Web API Search: why no WebIDs included of attributes?

          Hi Roger,


          Returning attribute WebIDs in the results is an enhancement request that is in our backlog. It will be included in the upcoming release.


          In order to support searching multiple object types and standard search engine features like paging and relevance sorting, Search was designed to support PI points and AF elements as top-level search results for this release.


          You could include matchedfields instead of attributes to get back only what has matched, in you case the attributename "KPI"


          As for the documentation, we will make it more consistent.


          Thanks for the feedback. Please let us know if you have any more questions.



            • Re: Pi Web API Search: why no WebIDs included of attributes?

              As Divya suggested, we can add matchedfields to the URL fields list as follows:




              This will add a MatchedFields array to each search result which can contain any field in the object that the search string matched on. In this case since the search was bound to only search attributename that will be the only field returned for results in this array. Note that this array is unordered. Also note * below regarding WebID.


              Also to extend upon the example given, if you are searching for a exact phrase to match, say an exact attribute name with multiple words like "Fuel Gas Flow", it's not currently possible. However you can use ANDs between search terms to find results with a field that at least matches all the containing words.


              I also agree the documentation could be improved.


              *My understanding of the next release is that the attribute WebID will only be present in the attributes object, so you will still receive all the attributes of a result object which you will then have to search for the attribute name of interest to find the WebID to use to access the data. Perhaps this makes the matchedfields suggestion not as useful to reduce the quantity of attributes that need to be processed and filtered for each search result but that may be negligible to the time gained by having immediate access to the attribute WebID and avoiding an additional GET per result.

                • Re: Pi Web API Search: why no WebIDs included of attributes?
                  Roger Palmen

                  Arnold, Divya,


                  Many thanks for your replies! Really like having WebIDs for the attributes! Good start of the day  Good to mention the matchedfields searchresult field, which will be soon have some description in the documentation.. I guessed the implicit wildcard behaviour of the search would imply we have all results that contain non-exact phrases, but there's nothing that AF attribute categories won't solve (pun intended).


                  And of course, this is all due to the fact that the REST concept does not fit AF very well. So no blame there. But in general, customers like the PI Web API due to it's simplicity, so using it in scenarios that are not in line with REST are quite obvious. And to be true, you need a first release to know what direction to take based on feedback, and in all the PI Web API is great to have!