When the JSON Schema for a collection contains a string enumeration, like the following:

{
  "properties": {
    "_id": {
      "bsonType": "objectId"
    },
    "enumExample": {
      "bsonType": "string",
      "enum": [
        "Foo",
        "Bar",
        "Baz"
      ],
      "title": "The type of entity that was favorited, such as a Workout."
    }
  },
  "required": [
    "_id",
    "enumExample"
  ],
  "title": "EnumExample"
}

... the generated Realm Object Models don't take advantage of the limited possible values. I've generated all of the available languages, and they all generate variations of a simple string.

Here's TypeScript as an example:

import Realm from "realm";
export type EnumExample = {
  _id: Realm.BSON.ObjectId;
  enumExample: string;
};
export const EnumExampleSchema = {
  name: 'EnumExample',
  properties: {
    _id: 'objectId',
    enumExample: 'string'
  },
  primaryKey: '_id',
};

Ideally, the generated type would be narrowed. Even more ideal would be enforcement of that at runtime, but I'm less knowledgeable about how that could work!

import Realm from "realm";
export type EnumExample = {
  _id: Realm.BSON.ObjectId;
  enumExample: "Foo" | "Bar" | "Baz"; // <--- this is the only line that changed
};
export const EnumExampleSchema = {
  name: 'EnumExample',
  properties: {
    _id: 'objectId',
    enumExample: 'string'
  },
  primaryKey: '_id',
};