How to conditionally add data to a groq-query if the array is empty

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.