Convert a JSON object to an Entities type

[muse254]

Category

User level API features/changes

Describe the feature you'd like to request

I have tried to look into the apis provided and can't find a way to convert a JSON dynamically to an Entity.
Say I have the JSON object

{
  "name": "John Doe",
  "age": 55,
  "is_staff": true,
  "contacts": {
    "email": "example@mail.com",
    "phone": 98978
  }
}

I would like to convert this to an Entities type with a function of maybe this signature

impl Entities {
   pub fn from_payload(schema: &Schema, type: &str, payload: &[u8])-> Result<Self>
}

Expected entities representation (might be erroneous)

[
    {
        "uid": {
            "type": "User",
            "id": "..."
        },
        "attrs": {
            "name": "John Doe",
            "age": 55,
            "is_staff": true,
            "contacts": {
                "type": "Contact",
                "id": "444"
            }
        },
        "parents": []
    },
    {
        "uid": {
            "type": "Contact",
            "id": "444"
        },
        "attrs": {
            "email": "example@mail.com",
            "phone": 98978
        },
        "parents": []
    }
]

It's not possible to write an own implementation since entityType is private to the crate consumer once parsed to the Schema type and also we wouldn't want to have different implementations in the wild.

Describe alternatives you've considered

I have tried to look into the apis provided for the Schema, Entities and can't find a way to convert a JSON dynamically to an Entities type.
Also, I haven't found any docs that describe this scenario.

Additional context

No response

Is this something that you'd be interested in working on?

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

[shaobo-he-aws]

Thank you for your interest in Cedar. We have a JSON format for entities, whose documentation can be found here. Once you specify entities in this format, you should be able to call Entities::from_json_str to get the Rust object.

Note that you may need to translate the JSON objects into Cedar's entity JSON format. We're exploring a solution (issue, rfc) that allows you to annotate the Rust type so that objects of a type can be automatically translated to Entities.

[muse254]

Could there be a possibility of making the proposed solution also have inclusion for dynamic generation of Entities for crate consumers who only get to know the schema and object they are parsing at runtime? @shaobo-he-aws
Or maybe a separate followup implementation

[shaobo-he-aws]

@muse254 Is it possible for you to depend on cedar_policy_validator? It should contain APIs you need to implement such function. In the meanwhile, we will try to make the required APIs to cedar_policy.

[cdisselkoen]

(note that cedar_policy_validator is not stable and does not come with semver guarantees)

[muse254]

Is it ok for me to start work on this under an experimental feature?

[aaronjeline]

That would be great, thank you!