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Relationship Queries: Check, Read, Expand, ListObjects and ListUsers

In this guide you will learn the uses of and limitations for the Check, Read, Expand, and ListObjects API endpoints.

Before you start​

In order to understand this guide correctly you must be familiar with some OpenFGA Concepts and know how to develop the things that we will list below.

Assume that you have the following authorization model.
You have a type called document that can have a reader and writer. All writers are readers. bob has a writer relationship with document:planning.

model
  schema 1.1

type user

type document
  relations
    define writer: [user]
    define reader: [user] or writer
[// Bob has writer relationship with planning document
  {
  "_description": "Bob has writer relationship with planning document",
  "user": "user:bob",
  "relation": "writer",
  "object": "document:planning"
}]

In addition, you will need to know the following:

Direct access​

You need to know how to create an authorization model and create a relationship tuple to grant a user access to an object. 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

Check​

What is it for?​

The Check API is an API endpoint that returns whether the user has a certain relationship with an object. OpenFGA will resolve all prerequisite relationships to establish whether a relationship exists.

When to use?​

Check can be called if you need to establish whether a particular user has a specific relationship with a particular object.

For example, you can call check to determine whether bob has a reader relationship with document:planning.

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:bob',
    relation: 'reader',
    object: 'document:planning',
  }, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA',
});

// allowed = true

The OpenFGA API will return true because there is an implied relationship as

  • every writer is also a reader
  • bob is a writer for document:planning

Caveats and when not to use it​

Check is designed to answer the question "Does user:X have relationship Y with object:Z?". It is not designed to answer the following questions:

  • "Who has relationship Y with object:Z?"
  • "What are the objects that userX has relationship Y with?"
  • "Why does user:X have relationship Y with object:Z?"

Batch Check​

What is it for?​

The Batch Check API is an API endpoint that allows you to check multiple user-object-relationship combinations in a single request.

When to use?​

Batching authorization checks together in a single request significantly reduces overall network latency.

Two scenarios are common to use Batch Check:

  1. When determining if the user has access to a list of objects (such as Option 1 in Search with Permissions), filter and sort on your database, then call /batch-check. Repeat to perform pagination.
  2. When determining fields on a web page the user has access to, call /batch-check for every relation necessary to show/hide each field.

For example, you can call Batch Check to determine whether bob has can_view_name, can_view_dob, and can_view_ssn relationships with patient_record:1.

curl -X POST $FGA_API_URL/stores/$FGA_STORE_ID/batch-check \
-H "Authorization: Bearer $FGA_API_TOKEN" \ # Not needed if service does not require authorization
-H "content-type: application/json" \
-d '{
  "authorization_model_id": "01HVMMBCMGZNT3SED4Z17ECXCA", 
  "checks": [
    {
      "tuple_key": {
        "user":"user:bob",
        "relation":"can_view_name",
        "object":"patient_record:1",
      },
      "correlation_id": "1"
    },
    {
      "tuple_key": {
        "user":"user:bob",
        "relation":"can_view_dob",
        "object":"patient_record:1",
      },
      "correlation_id": "2"
    },
    {
      "tuple_key": {
        "user":"user:bob",
        "relation":"can_view_ssn",
        "object":"patient_record:1",
      },
      "correlation_id": "3"
    },
  

# Response: 
{
  "results": {
    { "1": { "allowed": true }}, # can_view_name
    { "2": { "allowed": true }}, # can_view_dob
    { "3": { "allowed": false }}, # can_view_ssn
    
  }
}

The OpenFGA API will return true depending on the level of access assigned to that user and the implied relationships inherited in the authorization model.

Caveats and when not to use it​

If you are making less than 10 checks, it may be faster to call the Check API in parallel instead of Batch Check.

Read​

What Is It For?​

The Read API is an API endpoint that returns the relationship tuples that are stored in the system that satisfy a query.

When to use?​

Read can be called if you need to get all the stored relationship tuples that relate:

  1. a particular user to any objects of a specific type with a particular relation
  2. a particular user to any objects of a specific type with any relation
  3. a particular object to any user with a particular relation

1. A particular user to any objects of a specific type with a particular relation​

For example, to query all the stored relationship tuples bob has a writer relationship with, one can ask

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
});

// Execute a read
const { tuples } = await fgaClient.read({
  user:'user:bob',
relation:'writer',
object:'document:',
});

// tuples = [{"key": {"user":"user:bob","relation":"writer","object":"document:planning"}, "timestamp": "2021-10-06T15:32:11.128Z"}]

2. A particular user to any objects of a specific type with any relation​

For example, to query all the stored relationship tuples in which bob is related to objects of type document as any relation, one can issue the following call:

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
});

// Execute a read
const { tuples } = await fgaClient.read({
  user:'user:bob',
object:'document:',
});

// tuples = [{"key": {"user":"user:bob","relation":"writer","object":"document:planning"}, "timestamp": "2021-10-06T15:32:11.128Z"}]

3. A particular object to any user with a particular relation​

For example, to query all the stored relationship tuples in which any user is related to document:planning as a writer, one can issue the following call:

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
});

// Execute a read
const { tuples } = await fgaClient.read({
  relation:'writer',
object:'document:planning',
});

// tuples = [{"key": {"user":"user:bob","relation":"writer","object":"document:planning"}, "timestamp": "2021-10-06T15:32:11.128Z"}]

Caveats and when not to use it​

The Read API will only return all the stored relationships that match the query specification. It does not expand or traverse the graph by taking the authorization model into account.

For example, if you specify that writers are viewers in the authorization model, the Read API will ignore that and it will return tuples where a user is a viewer if and only if the (user_id, "viewer", object_type:object_id) relationship tuple exists in the system.

In the following case, although all writers have reader relationships for document objects and bob is a writer for document:planning, if you query for all objects that bob has reader relationships, it will not return document:planning.

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
});

// Execute a read
const { tuples } = await fgaClient.read({
  user:'user:bob',
relation:'reader',
object:'document:',
});

// tuples = []
info

Although bob is a writer to document:planning and every writer is also a reader, the Read API will return an empty list because there are no stored relationship tuples that relate bob to document:planning as reader.

Expand​

What is it for?​

The Expand API returns all users (including users and usersets) that have a specific relationship with an object. The response is represented as a tree of users or usersets. To build the full graph of access, you would need to recursively call expand on the leaves returned from the previous expand call.

When to use?​

Expand is used for debugging and to understand why a user has a particular relationship with a specific object.

For example, to understand why bob can have a reader relationship with document:planning, one could first call

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
});

const { tree } = await fgaClient.expand({
  relation: 'reader', // expand all who has 'reader' relation
  object: 'document:planning', // with the object 'document:planning'
}, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA'
});

// tree = ...

The result of this call will be like

{
  "tree":{
    "root":{
      "type":"document:planning#reader",
        "leaf":{
          "computed":{
            "userset":"document:planning#writer"
          }
        }
      }
    }
  }
}

The returned tree will contain writer, for which we will call

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
});

const { tree } = await fgaClient.expand({
  relation: 'writer', // expand all who has 'writer' relation
  object: 'document:planning', // with the object 'document:planning'
}, {
  authorization_model_id: '01HVMMBCMGZNT3SED4Z17ECXCA'
});

// tree = ...

The result of this call will be like

{
  "tree":{
    "root":{
      "type":"document:planning#writer",
        "leaf":{
          "users":{
            "users":[
              "user:bob"
            ]
          }
        }
      }
    }
  }
}

From there, we will learn that

  • those related to document:planning as reader are all those who are related to that document as writer
  • bob is related to document:planning as writer

ListObjects​

What is it for?​

The ListObjects API is an API endpoint that returns the list of all the objects of a particular type that a specific user has a specific relationship with.

It provides a solution to the Search with Permissions (Option 3) use case for access-aware filtering on small object collections.

When to use?​

Use the ListObjects API to get what objects a user can see based on the relationships they have. See Search with Permissions for more guidance.

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
});
const response = await fgaClient.listObjects({
  user: "user:bob",
  relation: "reader",
  type: "document",
      contextualTuples: {
    tuple_keys: [{
      user: "user:bob",
      relation: "reader",
      object: "document:otherdoc"
    }]
  },
}, {
  authorization_model_id: "01HVMMBCMGZNT3SED4Z17ECXCA",
});
// response.objects = ["document:otherdoc", "document:planning"]

There's two variations of the List Objects API.

  • The standard version, which waits until all results are ready and sends them in one response.
  • The streaming version, which should be used if you want the individual results as soon as they become available.

Caveats​

ListObjects will return the results found within the time allotted (listObjectsDeadline, default: 3s) up to the maximum number of results configured (listObjectsMaxResults, default: 1000). See Configuring the Server) for more on how to change the default configuration.

  • If you set listObjectsDeadline to 1s, the server will spend at most 1 second finding results.
  • If you set listObjectsMaxResults to 10, the server will return, at most, 10 objects.

If the number of objects of that type is high, you should set a high value for listObjectsDeadline. If the number of objects of that type the user could have access to is high, you should set a high value for listObjectsMaxResults.

ListUsers​

What is it for?​

The ListUsers API is an API endpoint that that returns all users of a given type that have a specified relationship with an object.

When to use?​

Use the ListUsers API to get which users have a relation to a specific object.

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
});
const response = await fgaClient.listUsers({
  object: {
    type: "document",
    id: "planning"
  },
  user_filters: [{
    type: "user"
  }],
  relation: "viewer",
}, {
  authorization_model_id: "01HVMMBCMGZNT3SED4Z17ECXCA",
});
// response.users = [{"object":{"type":"user","id":"anne"}},{"object":{"type":"user","id":"beth"}}]

Caveats​

ListUsers will return the results found within the time allotted (listUsersDeadline, default: 3s) up to the maximum number of results configured (listUsersMaxResults, default: 1000). See Configuring the Server) for more on how to change the default configuration.

  • If you set listUsersDeadline to 1s, the server will spend at most 1 second finding results.
  • If you set listUsersMaxResults to 10, the server will return, at most, 10 objects.

If the number of users matching that filter is high, you should set a high value for listUsersDeadline. If the number of users matching that filter that could have that relation with the object is high, you should set a high value for listUsersMaxResults.

Summary​

CheckReadExpandListObjectsListUsers
PurposeCheck if user has particular relationship with certain objectReturn all stored relationship tuples that match queryExpand the specific relationship on a particular objectList all objects of a particular type that a user has a specific relationship withList all users of a particular type that have a relation to a specific object
When to useValidate if user X can perform Y on object ZList stored relationships in systemUnderstand why user X can perform Y on object ZFilter the objects a user has access toList the users that have access to an object
Check out this additional content for more information on how to query relationships.
Check API Reference

Official reference guide for the Check API

Read API Reference

Official reference guide for the Read API

Expand API Reference

Official reference guide for the Expand API

ListObjects API Reference

Official reference guide for the ListObjects API

ListUsers API Reference

Official reference guide for the ListUsers API