Fields are selected if they are mentioned in the query.

• Names without underscore represent typically columns or SQL expressions from the table the query is run against. id, name, fullName, emailAddress

• Fields with underscores are called fields with a path. They are mapped to a joined or a merged dependency. For a join relationship, the join will be added to the SQL statement if the field is selected. For a merge relationship a second SQL query is run and the results are merged. Such a query might look like this book_id, book_title, book_createdBy_id, sellers_city

id, book_id

is translated into (assume a struct User that joins to a struct Book)

SELECT a.id, b.id FROM User a JOIN Book b ON (a.book_id = b.id)

There are two wildcards to select multiple fields. They can neither be filtered nor ordered.

• * selects all fields from the top level.

• path_* selects all fields from path.

Fields can be excluded from the wildcard by setting them to skip_wildcard.

So a query *, book_* would select all fields from user and book.

Fields can require roles to be loaded. An error is raised, if a query selects a field by name that it's not allowed to. However if the query selects with a wildcard, the disallowed field will just be ignored.