Annotations
Annotations are named values associated with schema items and are designed to hold arbitrary schema-level metadata represented as a str.
Standard annotations
There is a number of annotations defined in the standard library. The following are the annotations which can be set on any schema item:
title
description
deprecated
For example, consider the following declaration:
type Status {
annotation title := 'Activity status';
annotation description := 'All possible user activities';
required property name -> str {
constraint exclusive
}
}
The deprecated
annotation is used to mark deprecated items (e.g. str_rpad()) and to provide some information such as what should be used instead.
User-defined annotations
To declare a custom constraint type beyond the three built-ins, add an abstract annotation type to your schema. A custom annotation could be used to attach arbitrary JSON-encoded data to your schema—potentially useful for introspection and code generation.
abstract annotation admin_note;
type Status {
annotation admin_note := 'system-critical';
}
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See also |