GROQ: Conditional query based on empty array result

You can use the select() function in GROQ to handle conditional logic based on whether your array is empty! The select() function works like a switch statement and evaluates conditions in order.

Here's how you can modify your query:

{
  "users": select(
    count(*[_type=="user" && references(^._id)]) > 0 => *[_type=="user" && references(^._id)] {
      // initial data goes here...
      _id,
      name
    },
    // fallback data when no users found
    *[_type=="fallbackType"][0..10] {
      // new data structure here...
      _id,
      title
    }
  )
}

The key points here:

1. select() evaluates conditions in order and returns the first matching value
2. Use count() to check if the array has any items: count(*[_type=="user" && references(^._id)]) > 0
3. The first condition returns your user query with the initial data structure
4. The fallback (second parameter) returns alternative data when no users are found

Alternatively, you can use object-level conditionals if you want to conditionally include the entire field:

{
  count(*[_type=="user" && references(^._id)]) > 0 => {
    "users": *[_type=="user" && references(^._id)] {
      // initial data
    }
  },
  count(*[_type=="user" && references(^._id)]) == 0 => {
    "users": *[_type=="fallbackType"] {
      // fallback data
    }
  }
}

The select() approach is generally cleaner and more efficient since it stops at the first match rather than evaluating all conditions.