Properties​

Required properties​

Properties can be either optional (the default) or required.

type User {
  required email: str;
}

Property cardinality​

Properties have a cardinality, either single (the default) or multi. A multi property of type str points to an unordered set of strings.

type User {

  # single isn't necessary here
  # properties are single by default
  single name: str;

  # an unordered set of strings
  multi nicknames: str;

  # an unordered set of string arrays
  multi set_of_arrays: array<str>;
}

Comparison to arrays

The values associated with a multi property are stored in no particular order. If order is important, use an array. Otherwise, multi properties are recommended. For a more involved discussion, see EdgeQL > Sets.

Default values​

Properties can have a default value. This default can be a static value or an arbitrary EdgeQL expression, which will be evaluated upon insertion.

type Player {
  required points: int64 {
    default := 0;
  }

  required latitude: float64 {
    default := (360 * random() - 180);
  }
}

Readonly properties​

Properties can be marked as readonly. In the example below, the User.external_id property can be set at the time of creation but not modified thereafter.

type User {
  required external_id: uuid {
    readonly := true;
  }
}

Constraints​

Properties can be augmented wth constraints. The example below showcases a subset of EdgeDB’s built-in constraints.

type BlogPost {
  title: str {
    constraint exclusive; # all post titles must be unique
    constraint min_len_value(8);
    constraint max_len_value(30);
    constraint regexp(r'^[A-Za-z0-9 ]+$');
  }

  status: str {
    constraint one_of('Draft', 'InReview', 'Published');
  }

  upvotes: int64 {
    constraint min_value(0);
    constraint max_value(9999);
  }
}

You can constrain properties with arbitrary EdgeQL expressions returning bool. To reference the value of the property, use the special scope keyword __subject__.

type BlogPost {
  title: str {
    constraint expression on (
      __subject__ = str_trim(__subject__)
    );
  }
}

The constraint above guarantees that BlogPost.title doesn’t contain any leading or trailing whitespace by checking that the raw string is equal to the trimmed version. It uses the built-in str_trim() function.

For a full reference of built-in constraints, see the Constraints reference.

Annotations​

Properties can contain annotations, small human-readable notes. The built-in annotations are title, description, and deprecated. You may also declare custom annotation types.

type User {
  email: str {
    annotation title := 'Email address';
    annotation description := "The user's email address.";
    annotation deprecated := 'Use NewUser instead.';
  }
}

Abstract properties​

Properties can be concrete (the default) or abstract. Abstract properties are declared independent of a source or target, can contain annotations, and can be marked as readonly.

abstract property email_prop {
  annotation title := 'An email address';
  readonly := true;
}

type Student {
  # inherits annotations and "readonly := true"
  email: str {
    extending email_prop;
  };
}

Link properties​

Properties can also be defined on links. For a full guide, refer to Guides > Using link properties.