Part IX: Permissions & access control on data models

By default, the data APIs can only be accessed by users with the admin role. However, our blog app users will not have the admin role assigned. So, we need to allow access to the data APIs for roles other than admin. This is handled by the permission layer of the data microservice, which lets you define row level and column level access control policies for all the roles for different query types.

In our blog app, what roles do we have other than admin?

  1. user for logged in users
  2. anonymous for users who haven’t logged in.

We need to define permissions on all the tables that we have created so far for user and anonymous roles.

Let’s look at the access conditions we should set up for our tables:

Role Query type Columns Rows
anonymous select all columns all rows
anonymous insert not allowed
anonymous update none not allowed
anonymous delete not allowed
user select all columns all rows
user insert if user is the author
user update title, content if user is the author
user delete if user is the author
Role Query type Columns Rows
anonymous select all columns all rows
anonymous insert not allowed
anonymous update none not allowed
anonymous delete not allowed
user select all columns all rows
user insert their own row
user update name their own row
user delete their own row
Role Query type Columns Rows
anonymous select all columns all rows
anonymous insert not allowed
anonymous update none not allowed
anonymous delete not allowed
user select all columns all rows
user insert if user is giving the like
user update none not allowed
user delete if user gave the like
Role Query type Columns Rows
anonymous select all columns all rows
anonymous insert not allowed
anonymous update none not allowed
anonymous delete not allowed
user select all columns all rows
user insert if user is writing the comment
user update comment if user wrote the comment
user delete if user wrote the comment or is author of the article

To summarize:

  • anonymous role users can select (read) all the data
  • anonymous role users cannot modify (insert/delete/update) any data.
  • user role users can select (read) all the data.
  • user role users can insert/delete “their own data” and update only certain fields once inserted.

To define “their own data”, we can describe a condition using the value of the X-Hasura-User-Id header passed to the data microservice by the API gateway (as explained in the user, roles & sessions section).

The following are the conditions we will use while setting up the row level permissions described above:

Table Definition Condition Representation
All tables allow all rows Without any checks
{}
article user is author user-id is equal to author_id
{
  "author_id": {
    "$eq": "X-Hasura-User-Id"
  }
}
author user’s own row user-id is equal to id
{
  "id": {
    "$eq": "X-Hasura-User-Id"
  }
}
like user gave like user-id is equal to user_id
{
  "user_id": {
    "$eq": "X-Hasura-User-Id"
  }
}
comment user wrote comment user-id is equal to user_id
{
  "user_id": {
    "$eq": "X-Hasura-User-Id"
  }
}
comment user wrote comment or is author of article user-id is equal to user_id or user-id is equal to article's author_id (this requires a relationship called article to be defined first)
{
  "$or": [
    {
      "user_id": {
        "$eq": "X-Hasura-User-Id"
      }
    },
    {
      "article": {
        "author_id": {
          "$eq": "X-Hasura-User-Id"
        }
      }
    }
  ]
}

Defining permissions:

We can use the API console UI to add permissions for our tables. Head to Data -> [table-name] -> Permissions to see/modify the permissions on the table.

For example, let’s set the update permissions for user role on the article table:

The Permissions tab of the article table should look like this:

../../../_images/tutorial-permissions-tab1.png

Click on the Edit icon next to the user/update cell. It should open up an edit section like this:

../../../_images/tutorial-permissions-edit-empty1.png

Now, set the permissions as described above. It should finally look like this:

../../../_images/tutorial-permissions-edit-filled1.png

Hit Save permissions to save our changes.

Similary, set permissions for all the cases we have described above.

Next: Add aggregations and views

Next, head to Part X: Aggregations, views and custom relationships.