How to use select() with references to multiple document types in GROQ?

Yes! The select() function is exactly what you're looking for. Your current approach of assigning the same "title" key twice works because GROQ overwrites the first value with the second, but you're right that it's not ideal and could lead to unexpected behavior.

Here's the cleaner way using select():

*[_type == "story" && !(_id in path('drafts.**'))] | order(publicationDate desc) {
  "references": references[] {
    "title": select(
      reference->_type == "artist" => reference->name,
      reference->_type == "otherType" => reference->title
    )
  }
}

The select() function works like a switch statement - it evaluates conditions in order and returns the value for the first condition that matches. You can add as many conditions as you need for different document types, and optionally include a fallback value at the end:

"title": select(
  reference->_type == "artist" => reference->name,
  reference->_type == "venue" => reference->title,
  reference->_type == "event" => reference->eventName,
  "Untitled" // fallback if none match
)

This approach is more explicit, easier to maintain, and won't have any unexpected behavior when you scale to more complex queries. The select() function also short-circuits (stops evaluating once it finds a match), making it more efficient than your current approach.