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Using Multiple Fields for a Unique Key in Prisma

Using Multiple Fields for a Unique Key in Prisma

I encountered an issue with Prisma that took up some of my time, so I wanted to share how I resolved it.

In my model, I didn’t have an id field marked with @id, so I added @@unique() to define the user and tweet fields as a unique constraint.

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model Like {
  user Int
  tweet Int
  createdAt DateTime @default(now())
  @@unique([user, tweet])
}

This means that we cannot have duplicate entries with the same (user, tweet) combination.

When I attempted to delete an entry using the following code:

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await prisma.like.delete({
  where: {
    user: 1,
    tweet: 1
  }
})

I encountered an error message:

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PrismaClientValidationError: 
Invalid `prisma.like.delete()` invocation:

{
  where: {
    user: 12,
    ~~~~
    tweet: 22
    ~~~~~
  }
  ~~~~~~~~~~~
}

Argument where of type LikeWhereUniqueInput needs exactly one argument, but you provided user and tweet. Please choose one. Available args: 
type LikeWhereUniqueInput {
  user_tweet?: LikeUserTweetCompoundUniqueInput
}

To resolve this, I had to modify the code as follows:

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await prisma.like.delete({
  where: {
    user_tweet: {
      user: 1,
      tweet: 1
    }
  }
})

In other words, I had to concatenate the unique fields with an underscore.

Looking back, the error message did provide some explanation, but it wasn’t immediately clear to me.

tags: [“Prisma”, “Prisma issues”, “unique key”, “database constraints”]