Prisma一对一关联插入数据时pk字段非空约束报错排查

model ShopifyOfflineStoreSession {
  pk          String    @id(map: "PK_d371917bab72a48d6cce7880fc5") @default(dbgenerated("uuid_generate_v4()")) @db.Uuid
  id          String    @unique(map: "UQ_91ede9e23efbd7ee27b37bdd9ba") @db.VarChar
  store       Store?    @relation(fields: [pk], references: [shopifyOfflineSessionPk], onDelete: Cascade, onUpdate: Cascade, map: "FK_901a837fbbf20119aded3682f90")

  @@map("shopify_store_session")
}


model Store {
  id                       Int                         @id(map: "PK_f3172007d4de5ae8e7692759d79") @default(autoincrement())
  shopifyOfflineSessionPk  String?                     @unique(map: "UQ_901a837fbbf20119aded3682f90") @db.Uuid
  shopifyOfflineSession    ShopifyOfflineStoreSession?

  @@map("store")
}

await this.prisma.shopifyOfflineStoreSession.create({
  data: {
    ...session,
    store: { connect: { id: store.id } },
  },
});

2022-06-10 16:41:02.035 UTC [15541] ERROR:  null value in column "pk" violates not-null constraint
2022-06-10 16:41:02.035 UTC [15541] DETAIL:  Failing row contains (null, offline_subbooks2.myshopify.com, 2022-06-10 16:41:02.033, 2022-06-10 16:41:02.033, null, subbooks2.myshopify.com, 005148992241858, f, null, null, null).
2022-06-10 16:41:02.035 UTC [15541] STATEMENT:  INSERT INTO "public"."shopify_store_session" ("pk","id","createdAt","updatedAt","shop","state","isOnline") VALUES ($1,$2,$3,$4,$5,$6,$7) RETURNING "public"."shopify_store_session"."pk"
Issue saving Shopify offline token. Err: PrismaClientKnownRequestError:
Invalid `this.prisma.shopifyOfflineStoreSession.create()` invocation in
/usr/src/api/src/store/store.service.ts:576:52
   573     data: session,
   574   });
   575 } else {
→  576   await this.prisma.shopifyOfflineStoreSession.create(
  Null constraint violation on the fields: (`pk`)
    at cb (/usr/src/api/node_modules/@prisma/client/runtime/index.js:38683:17) {
  code: 'P2011',
  clientVersion: '3.6.0',
  meta: { constraint: [ 'pk' ] }
}
query: DELETE FROM "store" WHERE "id" IN ($1) -- PARAMETERS: [18]

核心问题是Prisma一对一关系配置完全写反：

• 现有配置在ShopifyOfflineStoreSession模型的store关系上，指定外键字段是当前模型的主键pk，关联Store模型的shopifyOfflineSessionPk字段。
• 这个配置的实际含义是：ShopifyOfflineStoreSession表的pk字段是外键，值必须从关联的Store记录的shopifyOfflineSessionPk字段获取。
• 执行connect关联已有Store记录时，Prisma会读取该Store的shopifyOfflineSessionPk值作为新Session的pk值，不会触发数据库配置的uuid_generate_v4()默认值生成逻辑。而此时待关联的Store记录的shopifyOfflineSessionPk本身就是空值（还未绑定Session），最终插入Session记录时pk字段为null，触发非空约束报错。

1. 修正关系配置，将外键定义挪到持有外键字段的Store模型侧，不要占用ShopifyOfflineStoreSession的主键字段当外键：

model ShopifyOfflineStoreSession {
  pk    String  @id(map: "PK_d371917bab72a48d6cce7880fc5") @default(dbgenerated("uuid_generate_v4()")) @db.Uuid
  id    String  @unique(map: "UQ_91ede9e23efbd7ee27b37bdd9ba") @db.VarChar
  store Store?

  @@map("shopify_store_session")
}

model Store {
  id                       Int                         @id(map: "PK_f3172007d4de5ae8e7692759d79") @default(autoincrement())
  shopifyOfflineSessionPk  String?                     @unique(map: "UQ_901a837fbbf20119aded3682f90") @db.Uuid
  // 外键在当前模型，关系配置写在这里
  shopifyOfflineSession    ShopifyOfflineStoreSession? @relation(
    fields: [shopifyOfflineSessionPk], 
    references: [pk], 
    onDelete: Cascade, 
    onUpdate: Cascade, 
    map: "FK_901a837fbbf20119aded3682f90"
  )

  @@map("store")
}

2. 修正Schema后执行prisma generate更新客户端，原有创建代码无需额外修改即可正常运行：Prisma会先生成带默认UUID主键的Session记录，再自动更新关联Store的shopifyOfflineSessionPk字段为新Session的主键值，不会再出现pk为null的问题。

内容的提问来源于stack exchange，提问作者Gezim