AbilityArgumentNormalizer.php
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ContentBlockHelper.php
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McpAnnotationMapper.php
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McpNameSanitizer.php
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McpValidator.php
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SchemaTransformer.php
2 months ago
SchemaTransformer.php
139 lines
| 1 | <?php |
| 2 | /** |
| 3 | * SchemaTransformer class for converting flattened schemas to MCP-compatible object schemas. |
| 4 | * |
| 5 | * @package McpAdapter |
| 6 | */ |
| 7 | |
| 8 | declare( strict_types=1 ); |
| 9 | |
| 10 | namespace WP\MCP\Domain\Utils; |
| 11 | |
| 12 | /** |
| 13 | * SchemaTransformer class. |
| 14 | * |
| 15 | * This class transforms flattened JSON schemas (e.g., type: string, number, boolean, array) |
| 16 | * into MCP-compatible object schemas. MCP requires all tool input schemas to be of type "object". |
| 17 | * |
| 18 | * @package McpAdapter |
| 19 | */ |
| 20 | class SchemaTransformer { |
| 21 | /** |
| 22 | * Transform a schema to MCP-compatible object format. |
| 23 | * |
| 24 | * If the schema is already an object type, it is returned unchanged. |
| 25 | * If the schema is a flattened type (string, number, boolean, array), it is |
| 26 | * wrapped in an object structure with a single property (defaults to "input"). |
| 27 | * |
| 28 | * @param array<string,mixed>|null $schema The JSON schema to transform. |
| 29 | * @param string $wrapper_key Property name to use when wrapping non-object schemas. |
| 30 | * |
| 31 | * @return array<string,mixed> Array containing 'schema', 'was_transformed' (bool), and 'wrapper_property' when transformed. |
| 32 | */ |
| 33 | public static function transform_to_object_schema( ?array $schema, string $wrapper_key = 'input' ): array { |
| 34 | // Convert any objects to arrays and strip empty properties. |
| 35 | // Abilities may contain objects from JSON decode cycles. Empty properties must be removed |
| 36 | // because MCP expects properties to be a JSON object, and PHP serializes empty arrays as []. |
| 37 | $schema = self::normalize( $schema ); |
| 38 | |
| 39 | // Handle null or empty schema - return minimal valid MCP object schema. |
| 40 | if ( empty( $schema ) ) { |
| 41 | return array( |
| 42 | 'schema' => array( |
| 43 | 'type' => 'object', |
| 44 | ), |
| 45 | 'was_transformed' => false, |
| 46 | 'wrapper_property' => null, |
| 47 | ); |
| 48 | } |
| 49 | |
| 50 | // If no type is specified, add 'object' type since MCP requires it. |
| 51 | if ( ! isset( $schema['type'] ) ) { |
| 52 | $schema['type'] = 'object'; |
| 53 | |
| 54 | return array( |
| 55 | 'schema' => $schema, |
| 56 | 'was_transformed' => false, |
| 57 | 'wrapper_property' => null, |
| 58 | ); |
| 59 | } |
| 60 | |
| 61 | // If already an object type, return as-is |
| 62 | if ( 'object' === $schema['type'] ) { |
| 63 | return array( |
| 64 | 'schema' => $schema, |
| 65 | 'was_transformed' => false, |
| 66 | 'wrapper_property' => null, |
| 67 | ); |
| 68 | } |
| 69 | |
| 70 | // Transform flattened schema to object format |
| 71 | return array( |
| 72 | 'schema' => self::wrap_in_object( $schema, $wrapper_key ), |
| 73 | 'was_transformed' => true, |
| 74 | 'wrapper_property' => $wrapper_key, |
| 75 | ); |
| 76 | } |
| 77 | |
| 78 | /** |
| 79 | * Wrap a flattened schema in an object structure. |
| 80 | * |
| 81 | * Creates an object schema with a single property (named by $wrapper_key) that |
| 82 | * contains the original flattened schema. |
| 83 | * |
| 84 | * @param array<string,mixed> $schema The flattened schema to wrap. |
| 85 | * @param string $wrapper_key Property name to wrap the value under. |
| 86 | * |
| 87 | * @return array<string,mixed> The wrapped object schema. |
| 88 | */ |
| 89 | private static function wrap_in_object( array $schema, string $wrapper_key ): array { |
| 90 | return array( |
| 91 | 'type' => 'object', |
| 92 | 'properties' => array( |
| 93 | $wrapper_key => $schema, |
| 94 | ), |
| 95 | 'required' => array( $wrapper_key ), |
| 96 | ); |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * Convert objects to arrays and strip empty properties. |
| 101 | * |
| 102 | * @param array<string,mixed>|null $schema The schema to normalize. |
| 103 | * |
| 104 | * @return array<string,mixed>|null The normalized schema. |
| 105 | */ |
| 106 | private static function normalize( ?array $schema ): ?array { |
| 107 | if ( null === $schema ) { |
| 108 | return null; |
| 109 | } |
| 110 | |
| 111 | $schema = self::convert_objects_to_arrays( $schema ); |
| 112 | |
| 113 | if ( array_key_exists( 'properties', $schema ) && is_array( $schema['properties'] ) && empty( $schema['properties'] ) ) { |
| 114 | unset( $schema['properties'] ); |
| 115 | } |
| 116 | |
| 117 | return $schema; |
| 118 | } |
| 119 | |
| 120 | /** |
| 121 | * Recursively convert objects to arrays. |
| 122 | * |
| 123 | * @param mixed $value The value to convert. |
| 124 | * |
| 125 | * @return mixed The converted value. |
| 126 | */ |
| 127 | private static function convert_objects_to_arrays( $value ) { |
| 128 | if ( is_object( $value ) ) { |
| 129 | $value = (array) $value; |
| 130 | } |
| 131 | |
| 132 | if ( is_array( $value ) ) { |
| 133 | return array_map( array( self::class, 'convert_objects_to_arrays' ), $value ); |
| 134 | } |
| 135 | |
| 136 | return $value; |
| 137 | } |
| 138 | } |
| 139 |