Database migration to postgre SQL instead of MongoDB

[bekogeko]

Currently, Prisma for MongoDB has some problems with relational fields and cycles. The main problem with MongoDB and Prisma is in the comment system there is a self-relation in a comment model.

There is an ideal model for the comment.

model Comment{
    parent   Comment?  @relation("ParentChild", fields: [parentId], references: [id], onUpdate: Cascade, onDelete: Cascade)
    children Comment[] @relation("ParentChild")
    parentId String?   @db.ObjectId
}

Take a look at the Cascade value in the onUpdate and onDelete values. The Cascade basically means do the same thing for me. For example, if we delete the parent, we will delete this comment too, and the same thing applies to onUpdate too. If the parent changes its id then update my parentId too.

But eventually, this cannot be achieved that easily because Prisma for MongoDB doesn't support self-relations except relation's onUpdate and onDelete actions set to NoAction. I think it's a deal-breaker for us but here I am for the discussions.

What if we switch to a fully supported Prisma connector?

That way we can freely use the full potential of the prisma while enjoying its beautiful schema and ORM system. But must keep in mind that this approach requires a lot of work and a lot of changes in the Data layer which can break most things.

Few examples of the problems:

• relational cycle problems (self relations)
• The Differences to relational databases

[dhincal]

In my opinion, we don't need to use the Cascade value in onUpdate because we don't really need to update the child comments when a parent updates (if we don't change ID of the parent and I think we shouldn't). But if we need to change the child when parent changes, then it looks like there is no option but switch the Prisma Connector.

[bekogeko]

@dhincal

I have another solution that doesn't require changing the MongoDB Provider. When we delete, we can delete the content and the shown authorName.

here is an example comment tree. (the id's of the comments were indicated as #.id)

- Bekogeko #.1
  a bad comment which will be deleted.
     - Deniz Hincal #.2
        so rude please delete this comment.
- Deniz Hincal #.3
   another root comment 

after we delete the #.1 comment the comment tree will look like this.

- comment deleted
  comment deleted 
     - Deniz Hincal #.2
        so rude please delete this comment.
- Deniz Hincal #.3
   another root comment 

with that approach, we can also delete comments on account deletion. Here is another tree for that

- account deleted
  comment deleted 
   - Deniz Hincal #.2
        so rude please delete this comment.
- Deniz Hincal #.3
   another root comment 
```

[bekogeko]

A solution prisma/prisma#17746