Multiple column + row permissions for the same role¶

Use case¶

In some cases we might want to allow access to certain columns for a role only if a particular condition is met while allowing access to other columns based on a different condition i.e. have different column permissions based on different row permissions.

Currently it is not possible to define multiple column + row permission rules for the same role.

We can work around this limitation by using views.

Example

Let’s say we have a table called user_info with columns (id, name, city, email, phone, address).

We want the role user to be able to access:

• the email, phone and address columns only if the id column is the requesting user’s id i.e. the current user is the owner of the row.
• the id, name and city columns for all rows.

We can achieve this via the following steps:

Step 1: Create a view¶

Create a view called user_private with columns (user_id, email, phone, address):

CREATE VIEW user_private AS
  SELECT id AS user_id, email, phone, address
    FROM user_info;

Step 2: Create a relationship¶

For the table user_info, create a manual object relationship called private_info using user_info : id -> user_private : user_id:

Step 3: Define permissions¶

For the role user, create the following permissions for select:

• Table user_info: allow access to id, name and city without any row conditions.

• View user_private: allow access to id, phone, email and address if the user-id passed in the session variable is equal to the row’s user_id.

Step 4: Query with appropriate access control¶

Now we can fetch the required data with the appropriate access control by using the relationship.

If the X-Hasura-Role and the X-Hasura-User-Id session variables are set to user and 2 respectively, we’ll get the following result:

query {
  user_info {
    id
    name
    city
    private_info {
      email
      phone
      address
    }
  }
}

Observe that the private_info field is returned as null for all rows without the appropriate access.