go-jsonschema is a tool to generate Go data types from JSON Schema definitions.

This tool generates Go data types and structs that corresponds to definitions in the schema, along with unmarshalling code that validates the input JSON according to the schema's validation rules.

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Installing

• Download: Get a release here.

• Install from source: To install with Go 1.25+:

go get github.com/atombender/go-jsonschema/...
go install github.com/atombender/go-jsonschema@latest

• Install with Brew: To install with Homebrew:

brew tap omissis/go-jsonschema
brew install go-jsonschema

Contributing

This project makes use of go workspaces in order to ease testing of the generated code during development while keeping the codebase as tidy and maintainable as possible. It's an unusual choice, but it allows to not only test the code-generation logic, but also the generated code itself.

Usage

At its most basic:

go-jsonschema -p main schema.json

This will write a Go source file to standard output, declared under the package main.

You can generate code for multiple schemas in one run, optionally writing to different files inside different packages:

$ go-jsonschema \
  --schema-package=https://example.com/schema1=github.com/myuser/myproject \
   --schema-output=https://example.com/schema1=schema1.go \
  --schema-package=https://example.com/schema2=github.com/myuser/myproject/stuff \
   --schema-output=https://example.com/schema2=stuff/schema2.go \
  schema1.json schema2.json

This will create schema1.go (declared as package myproject) and stuff/schema2.go (declared as package stuff). If schema1.json refers to schema2.json or viceversa, the two Go files will import the other depended-on package. Note the flag format:

--schema-package=https://example.com/schema1=github.com/myuser/myproject \
                 ^                           ^
                 |                           |
                 schema $id                  full import URL

Regenerating tests' golden files

It sometimes happen that new features or bug fixes to the library require regenerating the tests' golden files, here's how to do it:

export OVERWRITE_EXPECTED_GO_FILE="true"
make test

Special types

In a few cases, special types are used to help with serializing/deserializing data frrom JSON. Namely a custom types is provided for the following semantic types:

• SerializableDate
• SerializableTime

These types are needed because there is no native type provided by Go which properly handles them.

Status

While not finished, go-jsonschema can be used today. Aside from some minor features, only specific validations remain to be fully implemented.

Validation

• Core (RFC draft)
  • Data model (§4.2.1)
    • null
    • boolean
    • object
    • array
    • number
      • Option to use json.Number
    • string
  • Location identifiers (§8.2.3)
    • References against top-level names: #/$defs/someName
    • References against nested names: #/$defs/someName/$defs/someOtherName
    • References against top-level names in external files: myschema.json#/$defs/someName
    • References against nested names: myschema.json#/$defs/someName/$defs/someOtherName
  • Comments (§9)
• Validation (RFC draft)
  • Schema annotations (§10)
    • description
    • default (only for struct fields)
    • readOnly
    • writeOnly
    • title (N/A)
    • examples (N/A)
  • General validation (§6.1)
    • enum
    • type (single)
    • type (multiple; note: partial support, limited validation)
    • const
  • Numeric validation (§6.2)
    • multipleOf
    • maximum
    • exclusiveMaximum
    • minimum
    • exclusiveMinimum
  • String validation (§6.3)
    • maxLength
    • minLength
    • pattern
  • Array validation (§6.4)
    • items
    • maxItems
    • minItems
    • uniqueItems
    • additionalItems
    • contains
  • Object validation (§6.5)
    • required
    • properties
    • patternProperties
    • dependencies
    • propertyNames
    • maxProperties
    • minProperties
  • Conditional subschemas (§6.6)
    • if
    • then
    • else
  • Boolean subschemas (§6.7)
    • allOf
    • anyOf
    • oneOf
    • not
  • Semantic formats (§7.3)
    • Dates and times
    • Email addresses
    • Hostnames
    • IP addresses
    • Resource identifiers
    • URI-template
    • JSON pointers
    • Regex

License

MIT license. See LICENSE file.