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ZSS - Zog Schema Specification

ZSS (Zog Schema Specification) is an intermediate, structured representation of Zog schemas. It serves as a bridge between Zog's runtime schema definitions and other schema formats.

⚠️ Experimental API: ZSS is an experimental intermediate format that is still in flux. The structure and API are subject to breaking changes. Use with caution.

Purpose​

ZSS is designed to be an intermediate format that can be used to generate other schema formats such as:

  • JSON Schema (planned)
  • OpenAPI/Swagger specifications (planned)
  • TypeScript types (planned)
  • Other target formats as needed

By converting Zog schemas to ZSS first, we can generate multiple output formats from a single, well-defined intermediate representation.

Structure​

A ZSS document consists of:

  • ZSSDocument: The root container with version information and a root schema
  • ZSSSchema: Represents individual schema nodes with:
    • Kind: The schema type (string, number, bool, time, slice, struct, ptr, etc.)
    • Processors: Validation tests and transformers
    • Child: Nested schemas (for slices, structs, pointers, etc.)
    • GoTypes: Go type metadata (when exhaustive metadata is enabled)
    • Required, DefaultValue, CatchValue: Schema constraints and defaults

Usage​

Convert a Zog schema to ZSS using EXPERIMENTAL_TO_ZSS():

import (
    z "github.com/Oudwins/zog"
    zss "github.com/Oudwins/zog/pkgs/zss/core"
)

schema := z.String().Min(5)

// Convert to ZSS
zssDoc := z.EXPERIMENTAL_TO_ZSS(schema)

// Access the root schema
rootSchema := zssDoc.Root

Exhaustive Metadata​

ZSS supports an "exhaustive metadata" mode that includes additional information in the schema output. This mode must be explicitly enabled at build time.

Enabling Exhaustive Metadata​

To enable exhaustive metadata, build your application with the zogmeta build tag:

go build -tags zogmeta

Or when running tests:

go test -tags zogmeta

What's Included​

When exhaustive metadata is enabled, ZSS includes:

  • GoTypes: Array of ZSSGoType containing:

    • PkgPath: Package path (empty for built-in types)
    • Name: Type name (may be empty for unnamed types)
    • Display: Full type string representation

  • Format: For TimeSchema, the format string specified via z.Time(z.Time.Format(...)) is included in the ZSS output. Note: The format is only included in ZSS when exhaustive metadata is enabled.

  • Custom Messages: Custom messages set via z.Message() are included in the ZSS ZSSTest.Message field. Note: Custom messages are only included in ZSS output when exhaustive metadata is enabled.

For generic schemas like PreprocessSchema[F, T] and BoxedSchema[B, T], multiple type parameters are captured in the GoTypes array.

Example​

// With exhaustive metadata enabled
schema := z.Time(z.Time.Format(time.RFC3339))
schema := z.String().Min(5, z.Message("Custom validation message"))

zssDoc := z.EXPERIMENTAL_TO_ZSS(schema)
// Format and custom messages will be included in zssDoc

Notes​

  • The ZSS format is versioned via the $schema field
  • Currently, only version 0.0.1 is defined
  • The format may change significantly before stabilization