Special Type Mapping

Prisma	Zod (I/O)	Pure Models Default	Notes
String	z.string()	same	optional + .nullable() when optional string input variant
Int	z.number().int()	same
Float	z.number()	same
Boolean	z.boolean()	same
DateTime	z.date()	same	(strategy: date)
Json	z.unknown() + optional refinements	same	Optional depth/length validations
Bytes	z.instanceof(Uint8Array)	z.string() (base64)	Override to Uint8Array by useBase64:false
BigInt	z.bigint()	same
Decimal	z.custom(Prisma.Decimal.isDecimal)	same	Full Decimal.js support (configurable via decimalMode)
Enums	<Enum>Schema	<Enum>Schema	Generated enum schemas

Bytes: adds size constraints & base64 regex or length refinements depending on representation.

JSON: Can enforce serializability, depth, and length; adds descriptive comments in generated file.

Decimal Type Support

The Decimal type in Prisma is mapped to Zod schemas based on the decimalMode configuration option. This feature provides full compatibility with zod-prisma-types for seamless migration.

Configuration Options

Configure decimal handling via the decimalMode option in your config file:

{
  "decimalMode": "decimal" // "decimal" | "number" | "string"
}

Modes

decimal (Default, Recommended)

Full Decimal.js support matching zod-prisma-types implementation:

• Pure Models: z.custom<InstanceType<typeof Prisma.Decimal>>((v) => Prisma.Decimal.isDecimal(v)) with descriptive error messages
• Input Types: Union of number | string | Prisma.Decimal | Decimal (if decimal.js installed) with runtime validation
• Imports: Automatically imports Prisma (non-type import: Decimal.isDecimal checks and defaults need the runtime value). With the legacy prisma-client-js generator this is @prisma/client; with the new prisma-client generator and a custom output the import targets the generated client's browser-safe entrypoint (<output>/browser), so generated schemas can be bundled for the browser without pulling in node: builtins from the server entry.

Example Output:

// Pure model schema
export const ProductSchema = z.object({
  id: z.number().int(),
  price: z.custom<InstanceType<typeof Prisma.Decimal>>((v) => Prisma.Decimal.isDecimal(v), {
    message: "Field 'price' must be a Decimal. Location: ['Models', 'Product']",
  }),
});

Prisma.Decimal.isDecimal(v) is used instead of instanceof because the browser and server Prisma runtimes bundle separate copies of the Decimal class: an instanceof check would reject perfectly valid Decimal instances created by the other runtime copy (for example values revived on the client or produced by the schema's own .default(...)), while Decimal.isDecimal is cross-copy safe.

number

Legacy mode for backward compatibility:

• Maps Decimal fields to z.number()
• Warning: May lose precision for large decimal values
• Use when you don't need exact decimal precision

string

String-based validation with regex patterns:

• Maps Decimal fields to z.string() with decimal format validation
• Includes precision-aware regex patterns
• Preserves decimal precision as string representation

Migration from zod-prisma-types

If you're migrating from zod-prisma-types, use decimalMode: "decimal" (the default) for drop-in compatibility. The generator will:

1. Generate z.custom<InstanceType<typeof Prisma.Decimal>>((v) => Prisma.Decimal.isDecimal(v)) for model schemas
2. Create proper import statements for Prisma
3. Match the validation patterns from zod-prisma-types (with a cross-runtime-safe isDecimal check instead of instanceof)

Decimal.js Installation

While decimal.js is not required, installing it provides enhanced type safety:

pnpm add decimal.js

When decimal.js is installed, input schemas will also accept Decimal instances in the validation union.