Typescript type is not being inferred from Prisma query

[pavanputhra]

Question

I have following schema in Prisma

model User {
  id              String      @id @default(uuid())
  name            String
  email           String      @unique
}

When I write the following typescript code, I expect the return type to be correctly inferred, but the user variable is beeing infered as any type. Is it how prisma works, or am I doing something wrong?

const user = await prisma.user.findUnique({
  where: {
    email: "abc@example.com",
  }
});

Btw, I am using Prisma version 5.2.0

I have used the npx prisma generate. It generates proper type inference for input parameters. For example, if wrong field is set in where clause editor shows error. But only return value is inferred as Promise<any>

How to reproduce (optional)

Expected behavior (optional)

IDE should infer that return time is Promse<SomeUser>

Information about Prisma Schema, Client Queries and Environment (optional)

// Add your schema.prisma

// Add any relevant Prisma Client queries here

• OS: macOS

• Database: PostgreSQL

• Node.js version: v18

• Prisma version: 5.2.0

[nurul3101]

Hello @pavanputhra 👋

If you have invoked npx prisma generate command, then ideally, you should get the correct autocompletion.

Can you try this snippet and check if the IDE throws an error for you?

import { PrismaClient, User } from "@prisma/client";

const prisma = new PrismaClient({
  log: ["query"],
});

async function main() {
  await findUserByEmail("test@prisma.io");
}

export async function findUserByEmail(email: string): Promise<User | null> {
  return prisma.user.findUnique({
    where: {
      email,
    },
  });
}

main()
  .catch((e) => {
    throw e;
  })
  .finally(async () => {
    await prisma.$disconnect();
  });

[pavanputhra]

Hi @nurul3101 ,

Thanks for reply.

Manually adding Promise<User | null> works. I was hoping it get's automatically inferred depending on what findUnique returns.

Automatically inferring helps in:

1. Less work for developer as we don't have to add type annotation.
2. Sometimes types returned is dependent on select query. For example

export async function findUserByEmail(email: string)  {
  return prisma.user.findUnique({
    where: {
      email,
    },
    select: {
        id:true,
        email: true,
    }
  });
}

In the above scenario the return type should be Promise<{ id: string, email: string} | null> rather than Promise<User | null>

I think, I have seen some library which annotate with dynamic return type based on the arguments passed, but don't remember the name.

[TechNech]

How to counter for Enums?

[pavanputhra]

I figured out why type inference was not working. It is because of how i imported it.

Here is how I imported it.

import { createRequire } from 'module';
const require = createRequire(import.meta.url);
const { PrismaClient } = require('@prisma\/client');

Why did I import that way instead of regular import { PrismaClient } from '@prisma\/client';?

Regular import was causing SvelteKit build to fail, so I had to use above import approach.

Did I fix it?

Yes I fixed it in hacky way.

Now I use regular import.

import { PrismaClient } from '@prisma\/client';

IDE is happy and gives all type inference.

During build phase I use bash script to replace

import { PrismaClient } from '@prisma\/client';

with

import { createRequire } from 'module';
const require = createRequire(import.meta.url);
const { PrismaClient } = require('@prisma\/client');

So that svelte wont complain.