Theo's Typesafe Cult•3y ago

Handling duplicates with trpc

Lets say I have an User in Prisma database that has a Coin[] array in his model. Currently I'm doing something like this to display table of all items:

// Create an item
.mutation(async ({ ctx, input }) => {
      try {
        await ctx.prisma.coin.create({data: ...})}

// Then get all the items
getAll: publicProcedure.query(async ({ ctx }) => {
      try {
        return await ctx.prisma.coin.findMany({
          where: {userId: ctx.session?.user?.id}

// Create an item
.mutation(async ({ ctx, input }) => {
      try {
        await ctx.prisma.coin.create({data: ...})}

// Then get all the items
getAll: publicProcedure.query(async ({ ctx }) => {
      try {
        return await ctx.prisma.coin.findMany({
          where: {userId: ctx.session?.user?.id}

It works but the problem is that this way, person can add same items multiple times to this array since they all have unique ids. But if I try to make id not unique then if one user adds an item to his array, the rest cant. So im looking for a better way to handle this. Prisma schema for context:

model Coin {
  id                          String   @id @default(cuid())
  createdAt                   DateTime @default(now())
  name                        String
  other stuff but not important
}
model User {
  id            String    @id @default(cuid())
  name          String?
  email         String?   @unique
  emailVerified DateTime?
  image         String?
  accounts      Account[]
  sessions      Session[]
  coins         Coin[]
}

model Coin {
  id                          String   @id @default(cuid())
  createdAt                   DateTime @default(now())
  name                        String
  other stuff but not important
}
model User {
  id            String    @id @default(cuid())
  name          String?
  email         String?   @unique
  emailVerified DateTime?
  image         String?
  accounts      Account[]
  sessions      Session[]
  coins         Coin[]
}

11 Replies

Amos•3y ago

You can make the combination of Coin's id and a User's id unique maybe? Not sure if I understand the question Or make the name unique if you want people to only be able to create a coin that doesn't already exist? 🤔

noctateOP•3y ago

I thought about this but the problem is that Im currently displaying a table of coins and I want users to be able to add them to their favorites. But if one user adds a Bitcoin for example the others cant which sucks

Amos•3y ago

Ah I get what you are doing

noctateOP•3y ago

is there a way to write something like this in prisma?

ctx.prisma.user.coins.findmany where userId is the one that currently is clicking

ctx.prisma.user.coins.findmany where userId is the one that currently is clicking

cje•3y ago

You can make a combination of fields unique in Prisma

Amos•3y ago

You can add a table in between

cje•3y ago

https://www.prisma.io/docs/guides/general-guides/database-workflows/unique-constraints-and-indexes/mysql

Prisma

Unique constraints and indexes with Prisma and MySQL

Learn how to configure unique constraints and indexes with Prisma and MySQL by following the step-by-step instructions in this practical guide.

cje•3y ago

Look for @@unique

noctateOP•3y ago

Ill check it, thanks guys

Amos•3y ago

model Coin {
  id              String          @id @default(cuid())
  favouritedCoins FavouriteCoin[]
}

model FavouriteCoin {
  user   User   @relation(fields: [userId], references: [id], onDelete: Cascade)
  userId String
  coin   Coin   @relation(fields: [coinId], references: [id], onDelete: Cascade)
  coinId String

  @@unique([userId, coinId])
}

model User {
  id             String          @id @default(cuid())
  favouriteCoins FavouriteCoin[]
}

model Coin {
  id              String          @id @default(cuid())
  favouritedCoins FavouriteCoin[]
}

model FavouriteCoin {
  user   User   @relation(fields: [userId], references: [id], onDelete: Cascade)
  userId String
  coin   Coin   @relation(fields: [coinId], references: [id], onDelete: Cascade)
  coinId String

  @@unique([userId, coinId])
}

model User {
  id             String          @id @default(cuid())
  favouriteCoins FavouriteCoin[]
}

Idk maybe something like this if I get what you are trying to do

noctateOP•3y ago

ill try it out, thanks!

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Handling duplicates with trpc