Regression in 0.19.0: many-to-many relationships without explicit back-ref no longer generate the back-reference field on the related model

[borisno2]

Summary

In OpenSaaS Stack 0.18.x, a relationship({ ref: 'User', many: true }) field (many-to-many with only one side defined) would automatically generate an implicit back-reference field on the related model. In 0.19.0, this auto-generation has stopped, causing a Prisma schema validation error.

Regression

0.18.x behaviour (working)

Given:

// textMessage.ts
readBy: relationship({
  ref: 'User',
  many: true,
})

The generator produced in schema.prisma:

model TextMessage {
  readBy User[] @relation("TextMessage_readBy")
}

model User {
  readByMessages TextMessage[] @relation("TextMessage_readBy")  // auto-generated back-ref
}

0.19.0 behaviour (broken)

Same config now produces:

model TextMessage {
  readBy User[] @relation("TextMessage_readBy")
}

model User {
  // readByMessages field is MISSING
}

This triggers a Prisma validation error:

Error validating field `readBy` in model `TextMessage`: The relation field `readBy` on model `TextMessage`
is missing an opposite relation field on the model `User`.
Either run `prisma format` or add it manually.

Steps to Reproduce

1. Create a list with a many-to-many relationship where only one side is defined:

   const TextMessage = list({
     fields: {
       readBy: relationship({ ref: 'User', many: true }),
     },
   })

2. Run opensaas generate
3. Observe Prisma validation error

Expected Behaviour

Either:

1. Restore the auto-generated back-reference: The generator should add an implicit from_<List>_<field> back-reference field on the related model (as 0.18.x did), or
2. Document the breaking change: If the new behaviour intentionally requires explicit back-refs on both sides, document the migration path with a clear error message like "Relationship readBy is many-to-many but User has no back-reference field pointing to TextMessage.readBy"

Additional Context

• This affects any migration from Keystone 6 where many-to-many relationships had only one side defined (Keystone 6 similarly auto-generated back-references)
• Workaround: explicitly define the back-ref field on the related model AND update the ref to point to it