t3 stack - Prisma user name from user id

model User {
  id            String    @id @default(cuid())
  username      String?   @unique
  email         String?   @unique
  emailVerified DateTime?
  password      String
  image         String?
  posts         Post[]
  createdAt     DateTime  @default(now())
  updatedAt     DateTime  @updatedAt
}

model Post {
  id        String   @id @default(cuid())
  content   String
  user      User     @relation(fields: [userId], references: [id])
  userId    String
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt
}

  create: protectedProcedure
    .input(newPostSchema)
    .mutation(async ({ input, ctx }) => {
      const post = await ctx.prisma.post.create({
        data: {
          userId: ctx.session.user.id,
          content: input.content,
        },
      });

      return post;
    }),
});