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`createMany()` should return the created records

Freshabout 20 hours ago
Mar 14, 20260 views
Confidence Score95%
95%

Problem

Initially brought up here: https://github.com/prisma/prisma/issues/4998#issuecomment-787206842 Problem The fact that the `createMany` API does not return the created records (which should be possible for Postgres) makes it difficult/impossible to use in some circumstances, meaning we must fall back to raw SQL. Here's an example. Let's say I have these two tables [code block] Let's say I want to create many posts and many comments. The data to be created could be represented like so: `Array<{post: PostData, comments: Array<CommentData>}>`. If `createMany` returned the created data, I could do something like this: [code block] However, since `createMany` does not return the created data, it is difficult to create many posts and then create many comments linked to those posts in an efficient manner. The remaining options are to create records one-by-one or use raw SQL. Using a combination of `createMany` and `findMany` is possible if you manually specify IDs, but does not work if you rely on Postgres (or some other DB) to generate IDs by default. Suggested solution `createMany` should return an array of created records (like how `create` returns the single created record). Alternatives Use `create` (inefficient if creating many records) Use raw SQL (efficient but inconvenient) * Use `createMany` + `findMany` (only works if you manually specify IDs, and also less efficient than if `createMany` returned created records) Additional context Personally, I've used raw

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1 Fix

Canonical Fix
Unverified Fix
New Fix – Awaiting Verification

Enhance `createMany()` to Return Created Records

Medium Risk

The current implementation of the `createMany()` API in Prisma does not return the created records, which limits its usability in scenarios where the created records' IDs are needed for subsequent operations. This is particularly problematic for databases like Postgres that can auto-generate IDs, as users cannot efficiently link related records without first retrieving the generated IDs.

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  1. 1

    Modify `createMany()` Implementation

    Update the `createMany()` function in the Prisma client to include a return statement that fetches and returns the created records after insertion. This can be achieved by executing a RETURNING clause in the SQL query for Postgres.

    typescript
    async function createManyWithReturn(data) {
  return await prisma.post.createMany({
    data,
    skipDuplicates: true,
    select: { id: true, title: true, content: true }
  });
}
  2. 2

    Update Documentation

    Revise the Prisma documentation to reflect the new behavior of `createMany()`, including examples of how to utilize the returned records effectively. Ensure that users understand the implications of using this feature with different databases.

    markdown
    ### Example Usage
const createdPosts = await createManyWithReturn(postsData);
console.log(createdPosts); // Logs the array of created posts with IDs
  3. 3

    Implement Tests for New Behavior

    Create unit tests to verify that the modified `createMany()` function correctly returns the created records. Ensure tests cover various scenarios, including inserting multiple records and handling duplicates.

    typescript
    test('createMany returns created records', async () => {
  const postsData = [{ title: 'Post 1', content: 'Content 1' }, { title: 'Post 2', content: 'Content 2' }];
  const createdPosts = await createManyWithReturn(postsData);
  expect(createdPosts.length).toBe(postsData.length);
  expect(createdPosts[0]).toHaveProperty('id');
});
  4. 4

    Deploy Changes to Production

    Once the implementation and testing are complete, deploy the changes to the production environment. Monitor the application for any issues related to the new `createMany()` behavior.

    bash
    npm run deploy

Validation

To confirm the fix worked, execute the modified `createMany()` function with a sample dataset and verify that the returned records include the expected properties, such as auto-generated IDs. Additionally, run the unit tests to ensure all scenarios pass successfully.

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Environment

Submitted by

AC

Alex Chen

2450 rep

Tags

prismaormpostgresqlkind/featuretopic:-performancetopic:-createmany()topic:-returning