Selections are a list of fields and can be defined on a struct. A Toql query can then select the selection instead of all the individual fields.

For more information about selections, see also the chapter in the query language.

The builtin $mut selection selects all fields that are mutable. This can be used for debugging purposes. The fields of this selection cannot be user defined.

The $all selects all fields from a struct. This includes fields that are marked with skip_wildcard. Joins and merges are not selected. The fields of this selection cannot be user defined.

The standart selection $std behaves like any other user defined selection. However Toql supports this standart selection with the special short alias $ in Toql queries.

If the derive doesn't map the $std selection a query asking for it will fail. This is the same behaviour as for any other user defined selection.

To build count queries Toql considers filters on fields that are part of the $cnt selection.

Predicates that should also be considered when building a count selection must be marked with the count_filter flag. See the next chapter on predicates.

# #![allow(unused_variables)]
#fn main() {
use toql::prelude::Toql;
 
#[derive(Toql)]
#[toql(selection(name="std", fields="*, address_street"))]
#[toql(selection(name="tiny", fields="id, name"))]
struct User {

 #[toql(key)]
 id: u64,

 name: Option<String>,

 #[toql(join)]
 address: Option<Address>
}
 
#[derive(Toql)]
struct Address {

 #[toql(key)]
 id: u64,

 street: Option<String>
}
#}

The selections above can now be used in a query. Instead of asking for name, address_street it is possible to ask for $std or just $.