Handling null values when combining address fields in Sanity GROQ query

In GROQ, when you concatenate strings with the + operator, if any value is null, the entire result becomes null. To handle this, you can use the coalesce() function, which returns the first non-null value from its arguments.

For your address example, wrap each potentially null field with coalesce() and provide an empty string as the fallback:

"address": coalesce(address.line1, "") + '\n'
  + coalesce(address.line2, "") + '\n'
  + coalesce(address.city, "") + ', MA '
  + coalesce(address.zip, "")

This ensures that even if address.line2 (or any other field) is null, the concatenation still produces a valid string instead of returning null for the entire address.

Bonus tip for cleaner output: If you want to avoid extra newlines when line2 is empty, you can get more sophisticated with conditional logic:

"address": coalesce(address.line1, "") 
  + select(defined(address.line2) => '\n' + address.line2, '')
  + '\n' + coalesce(address.city, "") + ', MA '
  + coalesce(address.zip, "")

Or build it more explicitly with a conditional:

"address": coalesce(address.line1, "") 
  + (defined(address.line2) => ('\n' + address.line2) | '')
  + '\n' + coalesce(address.city, "") + ', MA '
  + coalesce(address.zip, "")

The coalesce() approach is a best practice in GROQ because it moves null-handling logic into your query rather than requiring defensive checks in your frontend code. This makes your application more robust and your data more predictable.