Custom functions

For advanced use cases where you need to regularly perform the same transformation it is also possible to write custom GROQ functions.

This is especially useful for complex schema types where you want to return the same attributes for different fields. For example resolving images or references the same way.

In the example below, both the headline and venue reference are passed into the same function which will resolve the reference and return the name attribute.

fn learn::reference($doc) = $doc->{name};

*[_type == "event"]{
  "headline": learn::reference(headline),
  "venue": learn::reference(venue)
}

This is a marked improvement from string interpolation with strings and variables in JavaScript and should result in shorter queries overall.