jsonschema

Generate JSON Schema out of Golang schema

Usage

First install the package

go get -u github.com/naveego/go-json-schema

Then create your generator file (see Example folder)

package main

import (
	"fmt"
	"github.com/naveego/go-json-schema"
)

type Domain struct {
	Data string `json:"data"`
}

func main(){
	fmt.Println(jsonschema.NewGenerator().WithRoot(&Domain{}).MustGenerate())
}

Definitions

To include a "definitions" element in your schema, you need to pass the definitions to the generator:

package main

import (
	"fmt"
	"github.com/naveego/go-json-schema"
)

type Domain struct {
	Child Child `json:"child"`
}

type Child struct {
	Data string `json:"data"`
}

func main(){
    js, err := jsonschema.NewGenerator().
        WithRoot(&Domain{}).
        WithDefinition("child", &Child{}).
        Generate()
    if err != nil {
    	panic(err)
    }
    fmt.Println(js.String())
}

Supported tags

• required:"true" - field will be marked as required
• title:"Title" - title will be added
• description:"description" - description will be added
• extensions:"{\"enumNames\": [\"A\",\"B\",\"C\"] }" - The JSON value of the tag will be merged into the resulting schema.

On an unexported field, these tags will be added to the schema for the struct itself rather than to the property representing the field.

On string fields:

• minLength:"5" - Set the minimum length of the value
• maxLength:"5" - Set the maximum length of the value
• enum:"apple|banana|pear" - Limit the available values to a defined set, separated by vertical bars
• const:"I need to be there" - Require the field to have a specific value.
• default:"some string value" - The default string value.

On numeric types (ints and floats)

• min:"-4.141592" - Set a minimum value
• max:"123456789" - Set a maximum value
• exclusiveMin:"0" - Values must be strictly greater than this value
• exclusiveMax:"11" - Values must be strictly smaller than this value
• const:"42" - Property must have exactly this value.
• default:"42" - The default numeric value.

Expected behaviour

If struct field is pointer to the primitive type, then schema will allow this type and null. E.g.:

type Domain struct {
	NullableData *string `json:"nullableData"`
}

Output

{
    "$schema": "http://json-schema.org/schema#",
    "type": "object",
    "properties": {
        "nullableData": {
            "anyOf": [
                {
                    "type": "string"
                },
                {
                    "type": "null"
                }
            ]
        }
    }
}