Prisma: What's the best way to model a many-to-many relationship with extra fields?

[mhasan2306]

🏷️ Discussion Type

Question

Body

Hi everyone,

I'm learning Prisma and working on a project where users can enroll in courses.

A user can enroll in multiple courses, and a course can have multiple users. I also need to store additional information for each enrollment, such as:

• enrolledAt
• progress
• status

Should I use Prisma's implicit many-to-many relation, or should I create an explicit join model?

If an explicit model is recommended, could someone explain why it's the better approach and share a simple schema example?

Thanks!

Guidelines

• I have read and understood this category's guidelines before making this post.

[webpromahdi]

When you need to store additional information about the relationship itself (such as enrolledAt, progress, or status), an explicit many-to-many relation is the recommended approach.

Instead of using Prisma's implicit many-to-many relation, create a dedicated join model.

Example:

model User {
id String @id @default(cuid())
enrollments Enrollment[]
}

model Course {
id String @id @default(cuid())
enrollments Enrollment[]
}

model Enrollment {
userId String
courseId String

enrolledAt DateTime @default(now())
progress Int @default(0)
status String

user User @relation(fields: [userId], references: [id])
course Course @relation(fields: [courseId], references: [id])

@@id([userId, courseId])
}

Using an explicit join model gives you several advantages:

• You can store additional metadata about the relationship.
• It's easy to track timestamps, progress, or status.
• Enrollment records can be queried and updated independently.
• The schema is much easier to extend as your application grows.

Implicit many-to-many relations are a good choice when you only need to know that two models are connected. However, once you need to store extra information about that connection, an explicit join model is the recommended and more scalable approach.