slasyz/jsonschema-go

JSON Schema mapping for Go

JSON Schema structures for Go

This library provides Go structures to marshal/unmarshal and reflect JSON Schema documents.

Reflector

Documentation.

type MyStruct struct {
    Amount float64 `json:"amount" minimum:"10.5" example:"20.6" required:"true"`
    Abc    string  `json:"abc" pattern:"[abc]"`
}

reflector := jsonschema.Reflector{}

schema, err := reflector.Reflect(MyStruct{})
if err != nil {
    log.Fatal(err)
}

j, err := json.MarshalIndent(schema, "", " ")
if err != nil {
    log.Fatal(err)
}

fmt.Println(string(j))

// Output:
// {
//  "required": [
//   "amount"
//  ],
//  "properties": {
//   "abc": {
//    "pattern": "[abc]",
//    "type": "string"
//   },
//   "amount": {
//    "examples": [
//     20.6
//    ],
//    "minimum": 10.5,
//    "type": "number"
//   }
//  },
//  "type": "object"
// }

Customization

By default, JSON Schema is generated from Go struct field types and tags. It works well for the majority of cases, but if it does not there are rich customization options.

Implementing interfaces on a type

There are a few interfaces that can be implemented on a type to customize JSON Schema generation.

• Preparer allows to change generated JSON Schema.
• Exposer overrides generated JSON Schema.
• RawExposer overrides generated JSON Schema.
• Described exposes description.
• Titled exposes title.
• Enum exposes enum values.
• NamedEnum exposes enum values with names.

And a few interfaces to expose subschemas (anyOf, allOf, oneOf, not and if, then, else).

• AnyOfExposer exposes anyOf subschemas.
• AllOfExposer exposes allOf subschemas.
• OneOfExposer exposes oneOf subschemas.
• NotExposer exposes not subschema.
• IfExposer exposes if subschema.
• ThenExposer exposes then subschema.
• ElseExposer exposes else subschema.

Configuring the reflector

Additional centralized configuration is available with jsonschema.ReflectContext and Reflect options.

• CollectDefinitions disables definitions storage in schema and calls user function instead.
• DefinitionsPrefix sets path prefix for definitions.
• PropertyNameTag allows using field tags other than json.
• InterceptType called for every type during schema reflection.
• InterceptProperty called for every property during schema reflection.
• InlineRefs tries to inline all references (instead of creating definitions).
• RootNullable enables nullability of root schema.
• RootRef converts root schema to definition reference.
• StripDefinitionNamePrefix strips prefix from definition name.
• PropertyNameMapping explicit name mapping instead field tags.
• ProcessWithoutTags enables processing fields without any tags specified.