14-transactions.md

Transactions

A database transaction refers to a sequence of read/write operations that are guaranteed to either succeed or fail as a whole.

The examples use the following prisma schema:

model Post {
    id        String   @id @default(cuid())
    createdAt DateTime @default(now())
    updatedAt DateTime @updatedAt
    published Boolean
    title     String
    content   String?

    comments Comment[]
}

model Comment {
    id        String   @id @default(cuid())
    createdAt DateTime @default(now())
    content   String

    post   Post   @relation(fields: [postID], references: [id])
    postID String
}

Successful scenario

A simple transaction could look as follows. Just omit the Exec(ctx), and provide the Prisma calls to client.Prisma.Transaction:

// create two posts at once and run in a transaction

firstPost := client.Post.CreateOne(
    db.Post.Published.Set(true),
    db.Post.Title.Set("First Post"),
).Tx()

secondPost := client.Post.CreateOne(
    db.Post.Published.Set(false),
    db.Post.Title.Set("Second Post"),
).Tx()

if err := client.Prisma.Transaction(firstPost, secondPost).Exec(ctx); err != nil {
    panic(err)
}

log.Printf("first post result: %+v", firstPost.Result())
log.Printf("second post result: %+v", secondPost.Result())

Failure scenario

Let's say we have one post record in the database:

{
    "id": "123",
    "title": "Hi from Prisma"
}

// this will fail, since the record doesn't exist...
a := client.Post.FindUnique(
    db.Post.ID.Equals("does-not-exist"),
).Update(
    db.Post.Title.Set("new title"),
).Tx()

// ...so this should be roll-backed, even though itself it would succeed
b := client.Post.FindUnique(
    db.Post.ID.Equals("123"),
).Update(
    db.Post.Title.Set("New title"),
).Tx()

if err := client.Prisma.Transaction(b, a).Exec(ctx); err != nil {
    // this err will be non-nil and the transaction will rollback,
    // so nothing will be updated in the database
    panic(err)
}

Next steps

Check out how to use json fields.