Theo's Typesafe Cult•2y ago

Manage items position field after delete

Hey, I'm working currently on todo list where user can change position of task using drag and drop. To do this i need number field on task to know on which position he is. And there is my question - if i have 5 items and someone deletes item 3 for example. should i change 4th and 5th items position to -1? I'm now using items length to set newly created task position (which isn't perfect i guess?). So, should I decrement positions that are higher than deleted one? Or there is some other solution? here is my Task schema

model Task {
    id          String  @default(cuid())
    position    Int
    text        String
    isCompleted Boolean @default(false)
    user        User    @relation(fields: [userId], references: [id])
    userId      String

    @@unique([id, position])
    @@index([userId])
}

model Task {
    id          String  @default(cuid())
    position    Int
    text        String
    isCompleted Boolean @default(false)
    user        User    @relation(fields: [userId], references: [id])
    userId      String

    @@unique([id, position])
    @@index([userId])
}

4 Replies

Neto•2y ago

It's a nice approach Even more considering that when you add the next item you can just get the highest position easily

Paweł•2y ago

Nice, that's encouraging! thx. Then I have small followup question, if I get all tasks with higher position then decrementing them in for loop with saving to db will be acceptable?

Neto•2y ago

Prisma does have a "native" decrement operation Just do it inside a transaction to avoid major issues

Paweł•2y ago

Oh, that's awesome 😄 Thanks a lot!

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Manage items position field after delete