fix(adapter-pg): properly serialize string values for JSON fields by buyuan-dev · Pull Request #29351 · prisma/prisma

buyuan-dev · 2026-03-18T14:21:54Z

Summary

Fixes a bug where plain string values could not be written to JSON fields in PostgreSQL.

Problem

When writing a plain string to a JSON field:

prisma.simple.create({data: {value: "hello"}})

PostgreSQL would reject with:

invalid input syntax for type json

This happened because the adapter was passing the string directly to node-postgres without JSON.stringify.

Fix

Ensure string values for JSON fields are properly serialized using JSON.stringify before being passed to the postgres driver.

Testing

Verified plain strings work in JSON fields
All existing adapter-pg tests pass
Numbers and booleans still work correctly

Fixes #29330

Summary by CodeRabbit

Bug Fixes
- JSON values are now correctly formatted when sent to PostgreSQL, preventing invalid JSON input errors.
Tests
- Added functional tests for JSON string-serialization behavior, a test matrix that excludes SQLite, and a schema setup used by the new tests.

Fixes prisma#29330 When writing plain string values to JSON fields in PostgreSQL, the adapter was passing the string directly to node-postgres without JSON.stringify. PostgreSQL expects valid JSON, so plain strings would fail with invalid input syntax for type json. The fix ensures string values for JSON fields are properly serialized using JSON.stringify before being passed to the postgres driver.

CLAassistant · 2026-03-18T14:22:03Z

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

coderabbitai · 2026-03-18T14:22:18Z

Walkthrough

PostgreSQL adapter now stringifies values for JSON scalar types so PostgreSQL receives valid JSON; new functional tests plus test matrix and Prisma schema files are added to validate JSON string-serialization behavior (SQLite excluded).

Changes

Cohort / File(s)	Summary
Postgres adapter conversion `packages/adapter-pg/src/conversion.ts`	Updates `mapArg` to stringify values when `argType.scalarType === 'json'`, preventing invalid input syntax for Postgres json; includes minor non-functional formatting tweaks.
Functional tests & matrix `packages/client/tests/functional/issues/29330-json-string-serialization/_matrix.ts`, `packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts`	Adds a test matrix that excludes SQLite and a test suite verifying writing/reading plain strings and various JSON-typed values to JSON fields.
Prisma test schema `packages/client/tests/functional/issues/29330-json-string-serialization/prisma/_schema.ts`	Adds a Prisma schema defining a `Document` model with `content: Json` and `metadata: Json?` for test setup.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: fixing proper serialization of string values for PostgreSQL JSON fields, which is the core objective of this PR.
Linked Issues check	✅ Passed	The PR addresses all coding requirements from issue `#29330`: implementing JSON.stringify for string values in JSON fields to fix 'invalid input syntax' errors, with comprehensive test coverage for various JSON types excluding SQLite.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to the linked issue: the adapter-pg fix for JSON serialization, test matrix configuration, schema setup, and functional tests for issue `#29330`.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

Create PR with unit tests

📝 Coding Plan

Generate coding plan for human review comments

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

coderabbitai

Actionable comments posted: 1

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: f9a71a27-97ad-495e-8db9-a4872bd321ed

📥 Commits

Reviewing files that changed from the base of the PR and between 33667c3 and 0e611fa.

📒 Files selected for processing (1)

packages/adapter-pg/src/conversion.ts

coderabbitai · 2026-03-18T14:27:41Z

packages/adapter-pg/src/conversion.ts

@@ -1,4 +1,4 @@
-import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'
+import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'


⚠️ Potential issue | 🟡 Minor

Remove BOM character from file.

There appears to be a Byte Order Mark (U+FEFF) character at the beginning of the file before import. This invisible character can cause issues with some build tools and linters.

🔧 Proposed fix

-import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils' +import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'

import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'

jacek-prisma

This needs a regression test based on the issue that is being addressed, you can have a look at packages/client/tests/functional/issues/29309-datetime-cursor for reference

buyuan-dev · 2026-03-19T00:37:08Z

@jacek-prisma ✅ Regression tests have been added, following the structure of #29309.

Test coverage:

String values correctly serialized to JSON fields
Various JSON types (string/number/boolean/null/object/array)
Uses PostgreSQL and other SQL databases (SQLite excluded)

Test files:

packages/client/tests/functional/issues/29330-json-string-serialization/_matrix.ts
packages/client/tests/functional/issues/29330-json-string-serialization/prisma/_schema.ts
packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts

Please let me know if the tests meet the requirements. Thanks!

coderabbitai

Actionable comments posted: 2

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 6143bed5-1db9-4700-862a-0921decdd0f9

📥 Commits

Reviewing files that changed from the base of the PR and between 0e611fa and 1ceb8d4.

📒 Files selected for processing (3)

packages/client/tests/functional/issues/29330-json-string-serialization/_matrix.ts
packages/client/tests/functional/issues/29330-json-string-serialization/prisma/_schema.ts
packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts

coderabbitai · 2026-03-19T00:39:53Z

packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts

+      // Test plain string value in JSON field
+      const document = await prisma.document.create({
+        data: {
+          content: 'hello world',
+          metadata: { author: 'test' },
+        },
+      })
+
+      expect(document.content).toBe('hello world')
+      expect(document.metadata).toEqual({ author: 'test' })
+
+      // Test with findMany
+      const found = await prisma.document.findFirst({


🧹 Nitpick | 🔵 Trivial

Remove stale/non-informative inline comments.

Line 21 says “findMany” but the code calls findFirst, and both comments here describe what the code does rather than why.

As per coding guidelines: “Avoid adding useless code comments that do not add new information. Only write inline comments explaining Why (context, background, GitHub issues, decisions), not What or How.”

packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts

coderabbitai

♻️ Duplicate comments (1)

packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts (1)
10-22: ⚠️ Potential issue | 🟡 Minor

Remove stale/non-informative inline comments.

These comments describe what the code does, and Line 21 is stale (findFirst is used, not findMany).
Proposed cleanup
-      // Test plain string value in JSON field
       const document = await prisma.document.create({
         data: {
           content: 'hello world',
           metadata: { author: 'test' },
         },
       })

       expect(document.content).toBe('hello world')
       expect(document.metadata).toEqual({ author: 'test' })

-      // Test with findMany
       const found = await prisma.document.findFirst({
         where: { id: document.id },
       })
As per coding guidelines: “Avoid adding useless code comments that do not add new information. Only write inline comments explaining Why (context, background, GitHub issues, decisions), not What or How.”

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: e8cc6b10-ae3c-4de6-997b-37ca7183802e

📥 Commits

Reviewing files that changed from the base of the PR and between 1ceb8d4 and be38c47.

📒 Files selected for processing (1)

packages/client/tests/functional/issues/29330-json-string-serialization/tests.ts

buyuan-dev · 2026-03-19T06:39:30Z

? Automated check: Token is configured correctly. I can now post comments and push fixes automatically.

jacek-prisma · 2026-03-23T12:36:31Z

Looks like mongodb is missing from the opt out list: https://github.com/prisma/prisma/actions/runs/23278580526/job/68178478878?pr=29351

coderabbitai bot reviewed Mar 18, 2026

View reviewed changes

jacek-prisma requested changes Mar 18, 2026

View reviewed changes

test: add regression test for JSON string serialization (prisma#29330)

1ceb8d4

coderabbitai bot reviewed Mar 19, 2026

View reviewed changes

fix: remove unused desc variable in test

be38c47

coderabbitai bot reviewed Mar 19, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

fix(adapter-pg): properly serialize string values for JSON fields#29351

fix(adapter-pg): properly serialize string values for JSON fields#29351
buyuan-dev wants to merge 3 commits intoprisma:mainfrom
buyuan-dev:fix/issue-29330

buyuan-dev commented Mar 18, 2026 •

edited by coderabbitai bot

Loading

Uh oh!

CLAassistant commented Mar 18, 2026

Uh oh!

coderabbitai bot commented Mar 18, 2026 •

edited

Loading

❌ Failed checks (1 warning)

Uh oh!

coderabbitai bot left a comment

Uh oh!

coderabbitai bot Mar 18, 2026

Uh oh!

jacek-prisma left a comment

Uh oh!

buyuan-dev commented Mar 19, 2026

Uh oh!

coderabbitai bot left a comment

Uh oh!

coderabbitai bot Mar 19, 2026

Uh oh!

Uh oh!

coderabbitai bot left a comment

Uh oh!

buyuan-dev commented Mar 19, 2026

Uh oh!

jacek-prisma commented Mar 23, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

		@@ -1,4 +1,4 @@
		import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'
		import { ArgType, type ColumnType, ColumnTypeEnum } from '@prisma/driver-adapter-utils'

Conversation

buyuan-dev commented Mar 18, 2026 • edited by coderabbitai bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Problem

Fix

Testing

Summary by CodeRabbit

Uh oh!

CLAassistant commented Mar 18, 2026

Uh oh!

coderabbitai bot commented Mar 18, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

❌ Failed checks (1 warning)

Uh oh!

coderabbitai bot left a comment

Choose a reason for hiding this comment

Uh oh!

coderabbitai bot Mar 18, 2026

Choose a reason for hiding this comment

Uh oh!

jacek-prisma left a comment

Choose a reason for hiding this comment

Uh oh!

buyuan-dev commented Mar 19, 2026

Uh oh!

coderabbitai bot left a comment

Choose a reason for hiding this comment

Uh oh!

coderabbitai bot Mar 19, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

coderabbitai bot left a comment

Choose a reason for hiding this comment

Uh oh!

buyuan-dev commented Mar 19, 2026

Uh oh!

jacek-prisma commented Mar 23, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

buyuan-dev commented Mar 18, 2026 •

edited by coderabbitai bot

Loading

coderabbitai bot commented Mar 18, 2026 •

edited

Loading