How can I automatically assign users to a node based on a taxonomy? I've Googled this but might just not be using the right search phrases. I'm building an RFP repository for my company. Each RFP question will have a Category assigned to it. Within Drupal, I'd like to:


Automatically assign one or more users as the SME (subject matter expert) based on the Category that was assigned to the question, e.g. if Category = Analytics, then automatically assign user 'John Smith' as the SME upon node creation. The users assigned to the question should be viewable on the node.
To do this, I'd need to have a mapping of Category => SME(s) table I'd assume.
The end goal, would be to use something like the Flag module to be able to notify those users via email if an RFP question that they are the SME for needs updating.
Ideally, there would be a way to automatically update existing nodes with the most current mapping of Category => SME (people leave, new people come onboard, etc.)
I would do something like this:


RFP question is a custom content type.
RFP question includes a term reference/entity reference to a taxonomy vocabulary called Category.
Category has an entity reference field (to users) called SME.  This way, each term can be assigned to a user.  If you do it this way, you also don't need to worry about updating existing nodes when the SME changes; you can simply update the term entry in the vocabulary Category once, and all relevant nodes will be changed.
With this config, the SME won't be visible on the node, just the category.  You can fix this by creating a block in Views and adding it to the node page.
You can use Flag with Rules to automatically notify by email the user marked as SME when a node is flagged for updating.