How to filter Search API index view by taxonomy parent I am using the default database server that comes with search api. I have the Hierarchy Index ticked and I also have the taxonomy field that I want selected.

Could someone give me instructions on how to configure the view to have it filtered by the taxonomy parent/show only the children of the selected parent term? I just want a drop down like you would have with a regular view.

(I got this to work in D7 a while ago but I think that was because the field still retained its taxonomy data type when indexed but now with D8 it has none of that.)


I can add a field that has a parent relationship but that does nothing.
I tried adding a field Vocabulary » Taxonomy term » Term Parents and tried to filter by that but nothing.
I just figured this out the answer was simpler than I thought. 

I was trying to use contextual filters &amp; relationships like other answers said but what worked was just simply adding the Taxonomy Field to Filter Criteria then selecting the desired parent. That's it. No need to add a relationship to it.

Edit:
There is still a problem: it doesn't work when using a grouped exposed filter it gives this error: 


  A value is required if the label for this item is defined.


Log Message:


  PHP -  Warning: trim() expects parameter 1 to be string, array given in ...


I tried changing the filter to Combined field filter with the Taxonomy as a field so the input would be string but I still get another error.


  PHP - Error: Call to undefined method ...