Properties

Properties are used to associate primitive data with an object type or link.

1. type Player {
2. property email -> str;
3. property points -> int64;
4. property is_online -> bool;
5. }

Properties are associated with a key (e.g. first_name) and a primitive type (e.g. str`` ). The term *primitive type* is an umbrella term that encompasses [scalar types](/read/edgedb-2.0-en/13073ed83100d341.md#ref-datamodel-scalars) likestrandbool`, enums, arrays, and tuples.

Required properties

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

1. type User {
2. required property email -> str;
3. }

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.

1. type User {

3. # single isn't necessary here
4. # properties are single by default
5. single property name -> str;

7. # an unordered set of strings
8. multi property nicknames -> str;

10. # an unordered set of string arrays
11. multi property set_of_arrays -> array<str>;
12. }

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.

1. type Player {
2. required property points -> int64 {
3. default := 0;
4. }

6. required property latitude -> float64 {
7. default := (360 * random() - 180);
8. }
9. }

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.

1. type User {
2. required property external_id -> uuid {
3. readonly := true;
4. }
5. }

Constraints

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

1. type BlogPost {
2. property title -> str {
3. constraint exclusive; # all post titles must be unique
4. constraint min_len_value(8);
5. constraint max_len_value(30);
6. constraint regexp(r'^[A-Za-z0-9 ]+$');
7. }

9. property status -> str {
10. constraint one_of('Draft', 'InReview', 'Published');
11. }

13. property upvotes -> int64 {
14. constraint min_value(0);
15. constraint max_value(9999);
16. }
17. }

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

1. type BlogPost {
2. property title -> str {
3. constraint expression on (
4. __subject__ = str_trim(__subject__)
5. );
6. }
7. }

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 can declare custom annotation types.

1. type User {
2. property email -> str {
3. annotation title := 'Email address';
4. annotation description := "The user's email address.";
5. annotation deprecated := 'Use NewUser instead.';
6. }
7. }

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.

1. abstract property email_prop {
2. annotation title := 'An email address';
3. readonly := true;
4. }

6. type Student {
7. # inherits annotations and "readonly := true"
8. property email extending email_prop -> str;
9. }

Link properties

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

︙