LLM-JSON-Cleaner

PHP library for sanitizing JSON responses from LLM APIs and validating them against a specified JSON schema.

Features

• JSON Response Cleaning: Remove unwanted artifacts.
• Schema Validation: Validate and enforce JSON schema constraints.

Installation

Install the package via Composer:

composer require edgaras/llm-json-cleaner

Usage

Extracting JSON from LLM Responses

require_once 'vendor/autoload.php';

use Edgaras\LLMJsonCleaner\JsonCleaner;

$llmResponse = "Hi there! Please find the details below:\n\n{
    \"task\": \"generate_report\",
    \"parameters\": {
        \"date\": \"2025-02-17\",
        \"format\": \"pdf\"
    }
}\n\nLet me know if you need further assistance.";

// Return JSON only
$extractJson = JsonCleaner::extract($llmResponse, false);
echo $extractJson;
// {"task":"generate_report","parameters":{"date":"2025-02-17","format":"pdf"}}

// Return JSON only as an array
$extractJsonAsArray = JsonCleaner::extract($llmResponse, true);
print_r($extractJsonAsArray);
// (
//  [task] => generate_report
//  [parameters] => Array
//      (
//          [date] => 2025-02-17
//          [format] => pdf
//      )
// )

Cleaning Malformed JSON

JsonCleaner::extract() automatically fixes common LLM output issues:

// Trailing commas
$json = JsonCleaner::extract('{"name": "Alice", "age": 30,}', true);
// ['name' => 'Alice', 'age' => 30]

// Single-quoted JSON
$json = JsonCleaner::extract("{'name': 'Alice'}", true);
// ['name' => 'Alice']

// Unquoted keys
$json = JsonCleaner::extract('{name: "Alice", active: true}', true);
// ['name' => 'Alice', 'active' => true]

// Multiline string values (literal newlines inside strings)
$json = JsonCleaner::extract('{"text": "line one
line two"}', true);
// ['text' => "line one\nline two"]

// Top-level arrays
$json = JsonCleaner::extract('Here: [{"id":1},{"id":2}] done.', true);
// [['id' => 1], ['id' => 2]]

Validating JSON Against a Schema

require_once 'vendor/autoload.php';

use Edgaras\LLMJsonCleaner\JsonValidator;


$json = '{
  "order_id": 401,
  "customer": "Alice",
  "payment_methods": [
    {
      "method_id": "p1",
      "type": "Credit Card"
    },
    {
      "method_id": "p2",
      "type": "PayPal"
    }
  ]
}';

$schema = [
  'order_id' => ['required', 'integer', 'min:1'],
  'customer' => ['required', 'string'],
  'payment_methods' => ['required', 'array', 'min:1'],
  'payment_methods.*.method_id' => ['required', 'string'],
  'payment_methods.*.type' => ['required', 'string'],
];

$validator = JsonValidator::validateSchema(json_decode($json, 1), $schema);
var_dump($validator);
// bool(true)


$schemaNotFull = [
  'order_id' => ['required', 'integer', 'min:1'],
  'customer' => ['required', 'string'], 
];

$validator2 = JsonValidator::validateSchema(json_decode($json, 1), $schemaNotFull);
print_r($validator2);
// Array
// (
//    [0] => Array
//        (
//            [payment_methods] => Array
//                (
//                    [0] => Unexpected field: payment_methods
//                )
//        )
// )

Validation Rules

Rule	Description
required	Field must be present and non-empty
nullable	Field may be null (skips other rules when null)
string	Must be a string
integer	Must be an integer
float	Must be a float or integer
numeric	Must be numeric (int, float, or numeric string)
boolean	Must be a boolean
array	Must be an array
email	Must be a valid email address
url	Must be a valid URL
date	Must be a valid date string
min:N	Minimum value (numbers) or minimum item count (arrays)
max:N	Maximum value (numbers) or maximum item count (arrays)
in:a,b,c	Value must be one of the listed options

Fields without required are optional - missing fields won't trigger errors, but present fields are still validated.

Nested array items are validated using wildcard dot notation: items.*.field_name

Unexpected fields (not defined in schema) are detected at all nesting levels.

Changelog

v1.1.0

JsonCleaner

• Added automatic trailing comma removal ({"a": 1,})
• Added single-quote to double-quote conversion ({'key': 'value'})
• Added unquoted key detection and quoting ({key: "value"})
• Added multiline string value sanitization (literal newlines inside JSON strings)
• Added top-level JSON array extraction ([...] embedded in text)
• All sanitization is string-aware - content inside quoted values is never corrupted

JsonValidator

• Added nullable rule - allows null values and skips further validation
• Added float rule - accepts floats and integers
• Added numeric rule - accepts any numeric value including numeric strings
• Added email, url, date validation rules
• Added optional field support - fields without required don't error when missing
• Added unexpected nested field detection inside wildcard arrays (not just top-level)
• Added sequential array check for wildcard (.*) paths - associative arrays are rejected
• Fixed required rule to allow false boolean values

General

• Tested and compatible with PHP 8.4 and PHP 8.5