Summary: SharePoint Online has unassigned refinable managed properties for each data type. To work around the restriction that a Title managed property is not sortable by default, you can map an unassigned refinable managed property.
I’m not going to introduce the search web parts in SharePoint in this article. I’m sure there are plenty of articles about that.
Today I’m looking at the managed properties in Office 365 as this is something that is different from the on-premises equivalent.
Out of the box, the managed property for Title doesn’t have sortable set:
Figure 1: In SharePoint Online, by default the Title managed property is not sortable.
This is probably not too much of a problem if you could simply edit the property and set Sortable to yes.
Figure 2: By default, you cannot set the sortable option for Title to yes in SharePoint Online.
Unfortunately, the Sortable option is something that you can’t modify.
So where does that leave me if I need to sort by title?
Create a new managed property? No, because for new properties this is also disabled!
Did Microsoft remove the sortable option in Office 365? No, they just hid it a bit.
There are many managed properties that start with Refinable… that do have the Sortable option enabled. These refinable properties are meant to be used by refinement panels. But there is no reason why they can’t be used in search web parts.
Figure 3: SharePoint Online has unmapped refinable properties for each data type.
For each data type (String, Date, Int, …) there is a different set of properties.
RefinableString00, RefinableString01, … all the way up to 20. “WHAT ONLY 20???”, I hear you shout.
Within Office 365 there are 20 refinable properties created for each datatype. Whenever you run out, SharePoint will, as if by magic, create another 100. And when you run out again, SharePoint will create another 100.
So back to the original question of how to make Title sortable. Pick an unmapped refinable property and map it to the Title field. Then use that refinable property in your search web parts and you can sort by Title.
You can find Pieter’s original article here: https://veenstra.me.uk/2016/06/30/office-365-making-the-title-field-sortable-in-content-search-and-search-results-web-parts/