jsonschemagen

README

generate

Generates Go (golang) Structs and Validation code from JSON schema.

Requirements

• Go 1.17+

Usage

Install

$ go get -u github.com/4thel00z/jsonschemagen/...

or

Build

$ make

Run

$ schema-generate exampleschema.json

Example

This schema

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "title": "Example",
  "id": "http://example.com/exampleschema.json",
  "type": "object",
  "description": "An example JSON Schema",
  "properties": {
    "name": {
      "type": "string"
    },
    "address": {
      "$ref": "#/definitions/address"
    },
    "status": {
      "$ref": "#/definitions/status"
    }
  },
  "definitions": {
    "address": {
      "id": "address",
      "type": "object",
      "description": "Address",
      "properties": {
        "street": {
          "type": "string",
          "description": "Address 1",
          "maxLength": 40
        },
        "houseNumber": {
          "type": "integer",
          "description": "House Number"
        }
      }
    },
    "status": {
      "type": "object",
      "properties": {
        "favouritecat": {
          "enum": [
            "A",
            "B",
            "C"
          ],
          "type": "string",
          "description": "The favourite cat.",
          "maxLength": 1
        }
      }
    }
  }
}

generates

package main

type Address struct {
  HouseNumber int `json:"houseNumber,omitempty"`
  Street string `json:"street,omitempty"`
}

type Example struct {
  Address *Address `json:"address,omitempty"`
  Name string `json:"name,omitempty"`
  Status *Status `json:"status,omitempty"`
}

type Status struct {
  Favouritecat string `json:"favouritecat,omitempty"`
}

See the test/ directory for more examples.

Documentation

Index

• func Output(w io.Writer, g *Generator, pkg string)
• type AdditionalProperties
  • func (ap *AdditionalProperties) UnmarshalJSON(data []byte) error
• type Field
• type Generator
  • func New(schemas ...*Schema) *Generator
  • func (g *Generator) CreateTypes() (err error)
• type RefResolver
  • func NewRefResolver(schemas []*Schema) *RefResolver
  • func (r *RefResolver) GetPath(schema *Schema) string
  • func (r *RefResolver) GetSchemaByReference(schema *Schema) (*Schema, error)
  • func (r *RefResolver) Init() error
  • func (r *RefResolver) InsertURI(uri string, schema *Schema) error
• type Schema
  • func Parse(schema string, uri *url.URL) (*Schema, error)
  • func ParseWithSchemaKeyRequired(schema string, uri *url.URL, schemaKeyRequired bool) (*Schema, error)
  • func ReadInputFiles(inputFiles []string, schemaKeyRequired bool) ([]*Schema, error)
  • func (schema *Schema) FixMissingTypeValue()
  • func (schema *Schema) GetRoot() *Schema
  • func (schema *Schema) ID() string
  • func (schema *Schema) Init()
  • func (schema *Schema) IsRoot() bool
  • func (schema *Schema) MultiType() ([]string, bool)
  • func (schema *Schema) Type() (firstOrDefault string, multiple bool)
• type Struct

Functions

func Output

func Output(w io.Writer, g *Generator, pkg string)

Output generates code and writes to w.

Types

type AdditionalProperties

type AdditionalProperties Schema

AdditionalProperties handles additional properties present in the JSON schema.

func (*AdditionalProperties) UnmarshalJSON

func (ap *AdditionalProperties) UnmarshalJSON(data []byte) error

UnmarshalJSON handles unmarshalling AdditionalProperties from JSON.

type Field

type Field struct {
	// The golang name, e.g. "Address1"
	Name string
	// The JSON name, e.g. "address1"
	JSONName string
	// The golang type of the field, e.g. a built-in type like "string" or the name of a struct generated
	// from the JSON schema.
	Type string
	// Required is set to true when the field is required.
	Required    bool
	Description string
}

Field defines the data required to generate a field in Go.

type Generator

type Generator struct {
	Structs map[string]Struct
	Aliases map[string]Field
	// contains filtered or unexported fields
}

Generator will produce structs from the JSON schema.

func New

func New(schemas ...*Schema) *Generator

New creates an instance of a generator which will produce structs.

func (*Generator) CreateTypes

func (g *Generator) CreateTypes() (err error)

CreateTypes creates types from the JSON schemas, keyed by the golang name.

type RefResolver

type RefResolver struct {
	// contains filtered or unexported fields
}

RefResolver allows references to be resolved.

func NewRefResolver

func NewRefResolver(schemas []*Schema) *RefResolver

NewRefResolver creates a reference resolver.

func (*RefResolver) GetPath

func (r *RefResolver) GetPath(schema *Schema) string

GetPath generates a path to given schema.

func (*RefResolver) GetSchemaByReference

func (r *RefResolver) GetSchemaByReference(schema *Schema) (*Schema, error)

GetSchemaByReference returns the schema.

func (*RefResolver) Init

func (r *RefResolver) Init() error

Init the resolver.

func (*RefResolver) InsertURI

func (r *RefResolver) InsertURI(uri string, schema *Schema) error

InsertURI to the references.

type Schema

type Schema struct {
	// SchemaType identifies the schema version.
	// http://json-schema.org/draft-07/json-schema-core.html#rfc.section.7
	SchemaType string `json:"$schema"`

	// ID{04,06} is the schema URI identifier.
	// http://json-schema.org/draft-07/json-schema-core.html#rfc.section.8.2
	ID04 string `json:"id"`  // up to draft-04
	ID06 string `json:"$id"` // from draft-06 onwards

	// Title and Description state the intent of the schema.
	Title       string
	Description string

	// TypeValue is the schema instance type.
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.6.1.1
	TypeValue interface{} `json:"type"`

	// Definitions are inline re-usable schemas.
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.9
	Definitions map[string]*Schema

	// Properties, Required and AdditionalProperties describe an object's child instances.
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.6.5
	Properties map[string]*Schema
	Required   []string

	// "additionalProperties": {...}
	AdditionalProperties *AdditionalProperties

	// "additionalProperties": false
	AdditionalPropertiesBool *bool `json:"-"`

	AnyOf []*Schema
	AllOf []*Schema
	OneOf []*Schema

	// Default can be used to supply a default JSON value associated with a particular schema.
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.10.2
	Default interface{}

	// Examples ...
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.10.4
	Examples []interface{}

	// Reference is a URI reference to a schema.
	// http://json-schema.org/draft-07/json-schema-core.html#rfc.section.8
	Reference string `json:"$ref"`

	// Items represents the types that are permitted in the array.
	// http://json-schema.org/draft-07/json-schema-validation.html#rfc.section.6.4
	Items *Schema

	// NameCount is the number of times the instance name was encountered across the schema.
	NameCount int `json:"-" `

	// Parent schema
	Parent *Schema `json:"-" `

	// Key of this schema i.e. { "JSONKey": { "type": "object", ....
	JSONKey string `json:"-" `

	// path element - for creating a path by traversing back to the root element
	PathElement string `json:"-"`

	// calculated struct name of this object, cached here
	GeneratedType string `json:"-"`
}

Schema represents JSON schema.

func Parse

func Parse(schema string, uri *url.URL) (*Schema, error)

Parse parses a JSON schema from a string.

func ParseWithSchemaKeyRequired

func ParseWithSchemaKeyRequired(schema string, uri *url.URL, schemaKeyRequired bool) (*Schema, error)

ParseWithSchemaKeyRequired parses a JSON schema from a string with a flag to set whether the schema key is required.

func ReadInputFiles

func ReadInputFiles(inputFiles []string, schemaKeyRequired bool) ([]*Schema, error)

ReadInputFiles from disk and convert to JSON schema.

func (*Schema) FixMissingTypeValue

func (schema *Schema) FixMissingTypeValue()

FixMissingTypeValue is backwards compatible, guessing the users intention when they didn't specify a type.

func (*Schema) GetRoot

func (schema *Schema) GetRoot() *Schema

GetRoot returns the root schema.

func (*Schema) ID

func (schema *Schema) ID() string

ID returns the schema URI id.

func (*Schema) Init

func (schema *Schema) Init()

Init schema.

func (*Schema) IsRoot

func (schema *Schema) IsRoot() bool

IsRoot returns true when the schema is the root.

func (*Schema) MultiType

func (schema *Schema) MultiType() ([]string, bool)

MultiType returns "type" as an array

func (*Schema) Type

func (schema *Schema) Type() (firstOrDefault string, multiple bool)

Type returns the type which is permitted or an empty string if the type field is missing. The 'type' field in JSON schema also allows for a single string value or an array of strings. Examples:

"a" => "a", false
[] => "", false
["a"] => "a", false
["a", "b"] => "a", true

type Struct

type Struct struct {
	// The ID within the JSON schema, e.g. #/definitions/address
	ID string
	// The golang name, e.g. "Address"
	Name string
	// Description of the struct
	Description string
	Fields      map[string]Field

	GenerateCode   bool
	AdditionalType string
}

Struct defines the data required to generate a struct in Go.