JSONB double-encoding when used with Drizzle ORM

Environment

• postgres: 3.4.0
• drizzle-orm: 0.30.0
• PostgreSQL: 15

Issue

When Drizzle ORM passes pre-stringified JSONB values, postgres-js stringifies them again, causing double-encoding.

// Drizzle passes: '{"foo":"bar"}'
// postgres-js serializes to: '"{\\"foo\\":\\"bar\\"}"'
// PostgreSQL stores: string instead of jsonb object

Root cause

postgres-js assumes all JSONB values need serialization:

// src/types.js
json: {
  to: 114,
  from: [114, 3802],  // 3802 = jsonb
  serialize: x => JSON.stringify(x),
  parse: x => JSON.parse(x)
}

However, ORMs like Drizzle pre-process values:

// Drizzle's PgJsonb.mapToDriverValue()
override mapToDriverValue(value: T['data']): string {
  return JSON.stringify(value);  // Already stringified
}

Result: JSON.stringify(JSON.stringify(value))

Reproduction

const { drizzle } = require('drizzle-orm/postgres-js')
const { pgTable, text, jsonb } = require('drizzle-orm/pg-core')
const postgres = require('postgres')

const client = postgres('postgresql://...')
const db = drizzle(client)

const test = pgTable('test', {
  id: text('id').primaryKey(),
  data: jsonb('data')
})

await db.insert(test).values({ id: '1', data: { foo: 'bar' } })

// SELECT jsonb_typeof(data) FROM test;
// Expected: "object"
// Actual: "string"

Workaround

Override type configuration:

const client = postgres(url, {
  types: {
    json: {
      to: 114,
      from: [114, 3802],
      serialize: x => x,  // Pass through
      parse: x => JSON.parse(x)
    }
  }
})

Suggestion

Check if value is already a string:

json: {
  to: 114,
  from: [114, 3802],
  serialize: x => typeof x === 'string' ? x : JSON.stringify(x),
  parse: x => JSON.parse(x)
}

This works for both ORM and direct usage scenarios.

Impact

Affects all ORMs that pre-process JSONB values (Drizzle, Prisma, TypeORM).

Related

• drizzle-team/drizzle-orm#724

Start with src/types.js and the provided Drizzle ORM reproduction, then inspect the existing JSON/JSONB type configuration. Verify behavior for both pre-stringified ORM values and direct JavaScript values; done means PostgreSQL stores the inserted JSONB as an object rather than a string without breaking direct usage.