Zod CoerceArray

coerceArray Function

When using Zod for schema validation, you may encounter situations where you want to accept both a single value and an array of values. The coerceArray function helps with this by transforming the input into an array format.

import type { ZodType } from 'zod';
import { z } from 'zod';

export function coerceArray<T extends ZodType>(schema: T) {
  return z
    .union([schema, z.array(schema)])
    .transform((rel) => (Array.isArray(rel) ? rel : [rel]) as T['_output'][]);
}

Usage Example

The following example demonstrates how to use the coerceArray function to validate and transform both single values and arrays into a consistent array format.

import { z } from 'zod';
import { coerceArray } from './coerceArray';

const schema = coerceArray(z.enum(['active', 'inactive']));

// Validating single values
schema.parse('active'); // ['active']
schema.parse(['active', 'inactive']); // ['active', 'inactive']