A JSON Schema generator for PHP

This library is a PHP based implementation for generating JSON Schemas, which can be easily extended with your own keywords and drafts. The library is most suitable for the case when you have many instances/datasets and a schema must be generated based on these instances/datasets.

The following drafts are natively supported:

• Draft 2020-12

Requirements

• PHP ^8.1

Installation

The library can be installed from a command line interface by using composer.

composer require ropi/json-schema-generator

Basic usage

<?php
$instances = [
    (object) [
        'firstname' => 'Foo',
        'age' => 18
    ],
    (object) [
        'firstname' => 'Bar',
        'age' => 29,
        'country' => 'DE'
    ]
];

$config = new \Ropi\JsonSchemaGenerator\Config\GenerationConfig(
    draft: new \Ropi\JsonSchemaGenerator\Draft\Draft202012()
);

$generator = new \Ropi\JsonSchemaGenerator\JsonSchemaGenerator($config);

foreach ($instances as $instance) {
    $generator->recordInstance($instance);
}

echo json_encode($generator->generateSchema(), JSON_PRETTY_PRINT);

Output of above example:

{
    "$schema": "https:\/\/json-schema.org\/draft\/2020-12\/schema",
    "type": "object",
    "required": [
        "firstname",
        "age"
    ],
    "properties": {
        "firstname": {
            "type": "string",
            "enum": [
                "Foo",
                "Bar"
            ]
        },
        "age": {
            "type": "integer",
            "enum": [
                18,
                29
            ]
        },
        "country": {
            "type": "string",
            "enum": [
                "DE"
            ]
        }
    },
    "additionalProperties": false
}

The generated schema is as restrictive as possible. The more instances are recorded, the better the generated schema is. Here is an example with more instances:

<?php
$instances = [
    (object) [
        'firstname' => 'Foo',
        'age' => 18
    ],
    (object) [
        'firstname' => 'Bar',
        'age' => 29,
        'country' => 'DE'
    ],
    (object) [
        'firstname' => 'Abc',
        'age' => 31,
        'country' => 'DE'
    ],
    (object) [
        'firstname' => 'Def',
        'age' => 44,
        'country' => 'AT'
    ],
    (object) [
        'firstname' => 'Ghi',
        'age' => 23,
        'country' => 'FR'
    ],
    (object) [
        'firstname' => 'Jkl',
        'age' => 33
    ],
    (object) [
        'firstname' => 'Mnop',
        'age' => 34
    ],
    (object) [
        'firstname' => 'Qrstuvw',
        'age' => 50
    ],
    (object) [
        'firstname' => 'xyz',
        'age' => 56
    ]
];

$config = new \Ropi\JsonSchemaGenerator\Config\GenerationConfig(
    draft: new \Ropi\JsonSchemaGenerator\Draft\Draft202012(),
    maxEnumSize: 8
);

$generator = new \Ropi\JsonSchemaGenerator\JsonSchemaGenerator($config);

foreach ($instances as $instance) {
    $generator->recordInstance($instance);
}

echo json_encode($generator->generateSchema(), JSON_PRETTY_PRINT);

Output of above example:

{
  "$schema": "https:\/\/json-schema.org\/draft\/2020-12\/schema",
  "type": "object",
  "required": [
    "firstname",
    "age"
  ],
  "properties": {
    "firstname": {
      "type": "string",
      "minLength": 3,
      "maxLength": 7,
      "examples": [
        "Foo",
        "Bar",
        "Abc",
        "Def",
        "Ghi",
        "Jkl",
        "Mnop",
        "Qrstuvw",
        "xyz"
      ]
    },
    "age": {
      "type": "integer",
      "minimum": 18,
      "maximum": 56,
      "examples": [
        18,
        29,
        31,
        44,
        23,
        33,
        34,
        50,
        56
      ]
    },
    "country": {
      "type": "string",
      "enum": [
        "DE",
        "AT",
        "FR"
      ]
    }
  },
  "additionalProperties": false
}