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Relationship Queries: Check, Read, Expand, and ListObjects

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.

type user
type document
relations
define writer as self
define reader as self or writer
[
// 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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

// Run a check
const { allowed } = await fgaClient.check({
tuple_key: {
user: 'user:bob',
relation: 'reader',
object: 'document:planning',
},
});

// 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?"

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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

// Execute a read
const { tuples } = await fgaClient.read({
tuple_key: {
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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

// Execute a read
const { tuples } = await fgaClient.read({
tuple_key: {
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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

// Execute a read
const { tuples } = await fgaClient.read({
tuple_key: {
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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

// Execute a read
const { tuples } = await fgaClient.read({
tuple_key: {
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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

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

// 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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});

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

// 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

Caveats And When Not To Use It

The Expand call is expensive and has high latency. As such, it is designed to be used for debugging and understanding why a user has a particular relationship with a specific object. It is not designed for checking whether a user has a particular relationship with a specific object. In that case the Check API call should be used instead.

ListObjects

What Is It For?

The ListObjects API is an API endpoint that returns the list of all the object IDs 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.

Note

The current implementation of List Objects API is not optimized and can return incomplete results. See below for more details.

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 { OpenFgaApi } = require('@openfga/sdk');

// Initialize the SDK with no auth - see "How to setup SDK client" for more options
const fgaClient = new OpenFgaApi({
apiScheme: process.env.FGA_API_SCHEME, // Either "http" or "https", defaults to "https"
apiHost: process.env.FGA_API_HOST, // required, define without the scheme (e.g. api.openfga.example instead of https://api.openfga.example)
storeId: process.env.FGA_STORE_ID, // Either "http" or "https", defaults to "https"
});
const response = await fgaClient.listObjects({
user: "user:bob",
relation: "reader",
type: "document",
contextual_tuples: {
tuple_keys: [{
user: "user:bob",
relation: "reader",
object: "document:otherdoc"
}]
},
});
// response.object_ids = ["otherdoc", "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 And When Not To Use It

The number of results returned by this API (both the standard and streaming version) may be incomplete depending on the listObjectsDeadline and listObjectsMaxResults configuration values (see Configuring the Server) provided to the OpenFGA server at startup. If you configure both values, the first one to be satisfied will terminate the request.

  • 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 object IDs.

Internally, the API runs concurrent checks against all the objects of the specified type. 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.

Warning

This API is provided to gather your feedback. Due to performance and high-latency considerations, we do not recommend using it in production yet.

Summary

CheckReadExpandListObjects
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 with
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 to
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