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Object to Object Relationships

In this guide you'll learn how to model your application with objects that are not specifically tied to a user. For example, a folder is a parent of a document.

When to use

This design pattern is helpful in the case where there are relationships between different objects. With OpenFGA, so long as both objects are in a type defined in the authorization model, relationship tuples can be added to indicate a relationship between them.

For example:

  • communities can contain channels
  • channels can contain posts
  • channels can contain threads
  • threads can contain posts
  • bookshelf can have books
  • trips can have bookings
  • account can contain transactions
  • buildings can have doors

Before you start​

To better follow this guide, make sure you're familiar with some OpenFGA Concepts and know how to develop the things listed below.

You will start with the authorization model below, it represents a document type that can have users related as editor, and folder type that can have users related as viewer.

model
  schema 1.1

type user

type document
  relations
    define editor: [user]

type folder
  relations
    define viewer: [user]

In addition, you will need to know the following:

Modeling user groups​

You need to know how to add users to groups and grant groups access to resources. Learn more →

OpenFGA concepts​

  • A Type: a class of objects that have similar characteristics
  • A User: an entity in the system that can be related to an object
  • A Relation: is a string defined in the type definition of an authorization model that defines the possibility of a relationship between an object of the same type as the type definition and a user in the system
  • An Object: represents an entity in the system. Users' relationships to it can be define through relationship tuples and the authorization model
  • A Relationship Tuple: a grouping consisting of a user, a relation and an object stored in OpenFGA

Step by step​

01. Create parent relations in document​

To represent that a folder can be a parent of a document, we first need to modify our document type definition to allow a parent relation.

model
  schema 1.1

type user

type document
  relations
    define parent: [folder]
    define editor: [user]

type folder
  relations
    define viewer: [user]

02. Add Parent Relationship Tuples​

Once the type definition is updated, we can now create the relationship between a folder as a parent of a document. To do this, we will create a new relationship tuple that describes: folder:budgets is a parent of document:may_budget.doc. In OpenFGA, users in the relationship tuples can not only be IDs, but also other objects in the form of type:object_id.

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

await fgaClient.write({
  writes: [
      // The user in this case is another object where the type is `folder` and the object_id is `budgets`
      {"_description":"The user in this case is another object where the type is `folder` and the object_id is `budgets`","user":"folder:budgets","relation":"parent","object":"document:may_budget.doc"}
  ],
}, {
  authorization_model_id: "01HVMMBCMGZNT3SED4Z17ECXCA" 
});

03. Check that parent folders have permissions​

Once that relationship tuple is added to OpenFGA, we can check if the relationship is valid by asking the following: "is folder:budgets a parent of document:may_budget.doc?"

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

// Run a check
const { allowed } = await fgaClient.check({
    user: 'folder:budgets',
    relation: 'parent',
    object: 'document:may_budget.doc',
  }, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA',
});

// allowed = true

It is important to note that the current authorization model does not imply inheritance of permissions. Even though folder:budgets is a parent of document:may_budget.doc, it does not inherit the editor relation from parent to document. Meaning editors on folder:budgets are not editors on document:may_budget.doc. Further configuration changes are needed to indicate that and will be tackled in a later guide.

caution

When creating relationship tuples for OpenFGA make sure to use unique ids for each object and user within your application domain. We are using first names and simple ids to just illustrate an easy-to-follow example.

Advanced object to object relationships​

Object to object can be used for more advanced use case, such as entitlements. An example use case is to allow subscribers to be entitled to different plans.

01. Create authorization model with object to object relationships​

To do this, the authorization model will have two types - feature and plan.

model
  schema 1.1

type user

type feature
  relations
    define associated_plan: [plan]
    define access: [user] or subscriber_member from associated_plan

type plan
  relations
    define subscriber_member: [user]

Type feature has two relations, associated_plan and access. Relation associated_plan allows associating plans with features while access defines who can access the feature. In our case, the access can be achieved either from

Here, we define plan as the user of object feature with relationship associated_plan rather than defining feature as the user of object plan with relationship feature. The reason we choose the former is that we want to describe our system in the following plain language:

  • A user can access a feature in a plan if they are a subscriber member of a plan that is the associated plan of a feature.

This will give us a flow of user->organization->plan->feature and allows us to answer the question of whether user can access a feature rather than whether user is subscriber of a plan.

02. Adding relationship tuples​

To realize the relationship, we will need to add the following relationship tuples.

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

await fgaClient.write({
  writes: [
      // make anne as subscriber_member for plan:advanced
      {"_description":"make anne as subscriber_member for plan:advanced","user":"user:anne","relation":"subscriber_member","object":"plan:advanced"},
      // The advanced plan is associated with the data preview feature
      {"_description":"The advanced plan is associated with the data preview feature","user":"plan:advanced","relation":"associated_plan","object":"feature:data_preview"}
  ],
}, {
  authorization_model_id: "01HVMMBCMGZNT3SED4Z17ECXCA" 
});

03. Check to see if access is allowed without direct relationship​

To validate that the authorization model and relationship tuples are correct, we can ask the question:

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

// Run a check
const { allowed } = await fgaClient.check({
    user: 'user:anne',
    relation: 'access',
    object: 'feature:data_preview',
  }, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA',
});

// allowed = true

We see that anne is allowed to access feature:data_preview without requiring direct relationship.

04. Disassociating plan from feature​

At any point in time, plan:advanced may be disassociated from feature:data_preview.

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

await fgaClient.write({
  deletes: [
      // Remove advanced plan from data preview feature
      { user: 'plan:advanced', relation: 'associated_plan', object: 'feature:data_preview'}
  ],
}, {
  authorization_model_id: "01HVMMBCMGZNT3SED4Z17ECXCA" 
});

When this is the case, anne will no longer have access to feature:data_preview even though she is still a subscriber_member of plan:advanced.

Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

// Run a check
const { allowed } = await fgaClient.check({
    user: 'user:anne',
    relation: 'access',
    object: 'feature:data_preview',
  }, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA',
});

// allowed = false
Initialize the SDK
// ApiTokenIssuer, ApiAudience, ClientId and ClientSecret are optional.
// import the SDK
const { OpenFgaClient } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaClient({
  apiUrl: process.env.FGA_API_URL, // required, e.g. https://api.fga.example
  storeId: process.env.FGA_STORE_ID,
  authorizationModelId: process.env.FGA_MODEL_ID, // Optional, can be overridden per request
});

// Run a check
const { allowed } = await fgaClient.check({
    user: 'user:anne',
    relation: 'subscriber_member',
    object: 'plan:advanced',
  }, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA',
});

// allowed = true
Check the following sections for more on how object-to-object relationships can be used.
Advanced Modeling Patterns: Entitlements

Learn how to model entitlement access patterns.

Modeling Parent-Child Relationships

Learn how to model parent and child relationships.

Modeling User Groups

Learn how to model user groups.