Model Permissions

To limit what data in a model is available to a role in your supergraph, you define a ModelPermissions object with a filter expression.

By default, whenever a new model is created in your supergraph, all records are only accessible to the admin role. You can think of these as permissions on rows in a typical relational database table.

You can restrict access to certain data by adding a new item to the permissions array in the ModelPermissions object. Each item in the array should have a role field and a select field. The select field should contain a filter expression that determines which rows are accessible to the role when selecting from the model.

Most commonly, you'll use session variables — accessed by Hasura Engine via your configured authentication mechanism in a JWT or body of a webhook response — to restrict access to rows based on the user's role, identity or other criteria.

This filter expression can reference

• The fields in your Model
• Logical operators: and, or and not
• fieldIsNull predicate
• fieldComparison predicate
• Relationship predicates
• null

To make a new ModelPermission or role available in your supergraph, after updating your metadata, you'll need to create a new build using the CLI.

Examples

Allow admin to access all rows in the Articles model but allow user to access rows where the author_id field matches the user id session variable. Basically, their own articles.

---
kind: ModelPermissions
version: v1
definition:
  modelName: Articles
  permissions:
    - role: admin
      select:
        filter: null
    - role: user
      select:
        filter:
          fieldComparison:
            field: author_id
            operator: _eq
            value:
              sessionVariable: x-hasura-user-id

Reference

See the ModelPermissions reference for more information.