drizzle-team/drizzle-orm · error · Error

Unknown array type

Error message

Unknown array type

What it means

In the AWS RDS Data API result mapper, an array-typed `Field` was returned but its `arrayValue` did not contain any of the recognized element arrays (`stringValues`, `longValues`, `doubleValues`, `booleanValues`, `arrayValues`). This is an unrecognized/nested array shape the mapper cannot decode.

Source

Thrown at drizzle-orm/src/aws-data-api/common/index.ts:36

		// eslint-disable-next-line unicorn/no-negated-condition
	} else if (field.arrayValue !== undefined) {
		if (field.arrayValue.stringValues !== undefined) {
			return field.arrayValue.stringValues;
		}
		if (field.arrayValue.longValues !== undefined) {
			return field.arrayValue.longValues;
		}
		if (field.arrayValue.doubleValues !== undefined) {
			return field.arrayValue.doubleValues;
		}
		if (field.arrayValue.booleanValues !== undefined) {
			return field.arrayValue.booleanValues;
		}
		if (field.arrayValue.arrayValues !== undefined) {
			return field.arrayValue.arrayValues;
		}

		throw new Error('Unknown array type');
	} else {
		throw new Error('Unknown type');
	}
}

export function typingsToAwsTypeHint(typings?: QueryTypingsValue): TypeHint | undefined {
	if (typings === 'date') {
		return TypeHint.DATE;
	} else if (typings === 'decimal') {
		return TypeHint.DECIMAL;
	} else if (typings === 'json') {
		return TypeHint.JSON;
	} else if (typings === 'time') {
		return TypeHint.TIME;
	} else if (typings === 'timestamp') {
		return TypeHint.TIMESTAMP;
	} else if (typings === 'uuid') {
		return TypeHint.UUID;

View on GitHub (pinned to b7862528fd)

Solutions

1. Cast the array column to a text representation in SQL (`array_col::text`) and decode it client-side.
2. Avoid selecting unsupported array element types through the Data API; fetch them via a non-array projection.
3. Upgrade drizzle-orm; newer versions add element-type handling for arrays.

Example fix

// before
const rows = await db.select({ arr: table.byteaArr }).from(table);
// after - cast to text
const rows = await db.execute(sql`select bytea_arr::text from t`);

// Cast exotic array columns to text before selecting via Data API
import { sql } from 'drizzle-orm';
const safe = await db.execute(sql`select bytea_arr_col::text from t`);

import type { Field } from '@aws-sdk/client-rds-data';
function hasKnownArrayValue(f: Field): boolean {
  const a = f.arrayValue;
  return !!a && (!!a.stringValues || !!a.longValues || !!a.doubleValues || !!a.booleanValues || !!a.arrayValues);
}

try {
  rows = await db.select({ arr: table.col }).from(table);
} catch (e) {
  if ((e as Error).message === 'Unknown array type') {
    rows = await db.execute(sql`select col::text from ${table}`);
  } else throw e;
}

When it happens

Trigger: Selecting an array column whose element type the RDS Data API represents with an unsupported/unhandled `arrayValue` variant (e.g. blob arrays, null arrays, or newer array element kinds). Triggered on the `getValueFromDataApi(field)` path during result decoding.

Common situations: Querying Postgres array columns with element types like `bytea[]`, `numeric[]` where the Data API returns a non-string/long/double/boolean variant, or after an AWS SDK upgrade that changed `arrayValue` shapes.

Related errors

• Unknown type
• Unknown type for ${value}
• Unexpected state: no column metadata found for index ${index
• Unexpected state: no column name for index ${index} found in
• Transaction not supported

AI-assisted analysis of drizzle-team/drizzle-orm@b7862528fd (2026-08-03). Data as JSON: /data/errors/930cef0573fe5dda.json. Report an issue: GitHub.