How to add a reference field ?

[alexandre-dos-reis]

Firstable, thank you for your work on this project !

I would like to add a reference to the user entity.

export const User = defineEntity({
  name: "User",
  tableName: "users",
  properties: (p) => ({
    ...primaryKeyProperty,
    firstName: p.string(),
    name: p.string(), // This refers to the lastname
    email: p.string().nullable(false).unique(),
    emailVerified: p.boolean(),
    banned: p.boolean().default(false),
    banReason: p.string().nullable(),
    banExpires: p.datetime().type("timestamptz").nullable(),
    image: p.string().type("varchar").nullable(),
    // I want to add a reference to the File entity here !
    imageFile: () => p.oneToOne(File).nullable(),
    //
    createdAt: p.datetime().type("timestamptz"),
    updatedAt: p.datetime().type("timestamptz"),
    sessions: () => p.oneToMany(Session).mappedBy("user"),
    accounts: () => p.oneToMany(Account).mappedBy("user"),
    messages: () => p.oneToMany(Message).mappedBy("user"),
  }),
});

In my better-auth config, I tried various things, notably :

export const auth = betterAuth({
  // ...
  user: {
      // I tried various combinaison here but unsuccessfull...
      imageFile: { type: "string", input: false, references: { field: "id", model: "files" } },
    },
  },
});

I keep getting an error from the plugin :

api 2026-02-23T15:13:12.178Z ERROR [Better Auth]: BetterAuthError 33 | var import_dset = require("dset");
api 34 |
api 35 | // src/utils/createAdapterError.ts
api 36 | var import_better_auth = require("better-auth");
api 37 | function createAdapterError(message) {
api 38 |   throw new import_better_auth.BetterAuthError(`[Mikro ORM Adapter] ${message}`);
api                                     ^
api BetterAuthError: [Mikro ORM Adapter] Can't find property "imageFile" on entity "User".
api       at /home/alex/dev/ea-core/node_modules/.bun/better-auth-mikro-orm@0.4.3+84d9f69fd3d49d0b/node_modules/better-auth-mikro-orm/lib/adapter.cjs:38:32
api
api # SERVER_ERROR:  33 | var import_dset = require("dset");
api 34 |
api 35 | // src/utils/createAdapterError.ts
api 36 | var import_better_auth = require("better-auth");
api 37 | function createAdapterError(message) {
api 38 |   throw new import_better_auth.BetterAuthError(`[Mikro ORM Adapter] ${message}`);
api                                     ^
api BetterAuthError: [Mikro ORM Adapter] Can't find property "imageFile" on entity "User".

Is this supported ?
Thank you.

[octet-stream]

Hi and thanks for reaching me out. I haven't had a chance to try defineEntity, so I'm not sure if I need some work to support it yet. I will look into that when I have time. But with decorators you don't actually need to pass anything to better-auth – the references should work out of the box. Though, again, I haven't tried joins support in better auth yet.