Schemadef

Simple CLI to generate defaults from JSON schema. Supports $defs. Does not support recursive $refs and JSON pointer URIs. Can also be used as a Clojure/script library.

CLI Usage

Here's the manpage:

NAME:
 schemadef - Generate defaults from JSON schema

USAGE:
  schemadef [command options] [arguments...]

VERSION:
 x.x.x

OPTIONS:
   -i, --input f   Path to JSON schema
   -s, --schema S  JSON schema literal
   -o, --output S  Output path. If not specified, prints to STDOUT.
   -?, --help

Example

Let's say we have the following schema saved as schema.json.

{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "title": "example",
    "type": "object",
    "properties": {
        "name": {
            "type": "string",
            "default": "adam"
        },
        "detail": {
            "type": "object",
            "properties": {
                "age": {
                    "$ref": "#/$defs/age"
                },
                "dim": {
                    "$ref": "#/$defs/dim"
                }
            }
        }
    },
    "$defs": {
        "age": {
            "type": "number",
            "default": 1
        },
        "height": {
            "type": "number",
            "default": 179
        },
        "dim": {
            "type": "object",
            "properties": {
                "height": {
                    "$ref": "#/$defs/height"
                }
            }
        }
    }
}

When schemadef -i schema.json is run, this gets printed to STDOUT:

{"name":"adam","detail":{"age":1,"dim":{"height":179}}}

You can use schemadef -i schema.json -o default.json to have the output be saved in a file.

Installation

Prebuilt binary coming soon.

Building from source

You will need to have the following dependencies on your system:

• Graal 21
• Clojure

Next, create the uberjar with clojure -T:build uberjar. Then create the native image with clojure -T:build native-image. The binary schemadef will be in the /target folder.

Use as a lib

Schemadef can also be used as a library.

deps.edn

org.clojars.some/schemadef {:mvn/version "0.2.20"}

Leiningen

[org.clojars.some/schemadef "0.2.20"]

Example

(require '[schemadef.lib :refer [gen-default]])
(gen-default (slurp "schema.json"))