feat: allow detection of schema version

Author: kylef

CHANGELOG.md

@@ -11,6 +11,7 @@
 
 - `uri` format is now validated.
 - Support for Swift 4 and 5.
+- Added support for JSON Schema Draft 6 and 7.
 
 ### Bug Fixes
 

Sources/Draft4Validator.swift

@@ -2,7 +2,7 @@ import Foundation
 
 public class Draft4Validator: Validator {
   let schema: [String: Any]
-  let metaSchema: [String: Any] = DRAFT_04_META_SCHEMA
+  static let metaSchema: [String: Any] = DRAFT_04_META_SCHEMA
   let resolver: RefResolver
 
   typealias Validation = (Validator, Any, Any, [String: Any]) -> (ValidationResult)

Sources/Draft7Validator.swift

@@ -2,7 +2,7 @@ import Foundation
 
 public class Draft7Validator: Validator {
   let schema: [String: Any]
-  let metaSchema: [String: Any] = DRAFT_07_META_SCHEMA
+  static let metaSchema: [String: Any] = DRAFT_07_META_SCHEMA
   let resolver: RefResolver
 
   typealias Validation = (Validator, Any, Any, [String: Any]) -> (ValidationResult)

Sources/JSONSchema.swift

@@ -52,7 +52,7 @@ public struct Schema {
   }
 
   public func validate(_ data: Any) -> ValidationResult {
-    let validator = Draft4Validator(schema: schema)
+    let validator = JSONSchema.validator(for: schema)
     return validator.validate(instance: data)
   }
 }
@@ -67,9 +67,29 @@ func validatorCurry(_ validator: @escaping (Draft4Validator, Any, Any, [String:
 }
 
 
+func validator(for schema: [String: Any]) -> Validator {
+  guard let schemaURI = schema["$schema"] as? String else {
+    return Draft4Validator(schema: schema)
+  }
+
+  if let id = Draft7Validator.metaSchema["$id"] as? String, schemaURI == id {
+    return Draft7Validator(schema: schema)
+  }
+
+  if let id = Draft6Validator.metaSchema["$id"] as? String, schemaURI == id {
+    return Draft6Validator(schema: schema)
+  }
+
+  if let id = Draft4Validator.metaSchema["$id"] as? String, schemaURI == id {
+    return Draft4Validator(schema: schema)
+  }
+
+  return Draft4Validator(schema: schema)
+}
+
+
 public func validate(_ value: Any, schema: [String: Any]) -> ValidationResult {
-  let validator = Draft4Validator(schema: schema)
-  return validator.validate(instance: value)
+  return validator(for: schema).validate(instance: value)
 }
 
 

Tests/JSONSchemaTests/JSONSchemaCases.swift

@@ -17,7 +17,7 @@ func draft4Validator(schema: Any, instance: Any) -> ValidationResult {
   }
 
   if let schema = schema as? [String: Any] {
-    return Draft4Validator(schema: schema).validate(instance: instance)
+    return validate(instance, schema: schema)
   }
 
   fatalError()

Tests/JSONSchemaTests/JSONSchemaTests.swift

@@ -50,3 +50,51 @@ class JSONSchemaTests: XCTestCase {
     XCTAssertFalse(schema.validate(["price": 34.99]).valid)
   }
 }
+
+
+class ValidateTests: XCTestCase {
+  func testValidateDraft4() {
+    let schema: [String: Any]  = [
+      "$schema": "http://json-schema.org/draft-04/schema#",
+      "type": "object",
+      "properties": [
+        "name": ["type": "string"],
+        "price": ["type": "number"],
+      ],
+      "required": ["name"],
+    ]
+
+    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+  }
+
+  func testValidateDraft6() {
+    let schema: [String: Any]  = [
+      "$schema": "http://json-schema.org/draft-06/schema#",
+      "type": "object",
+      "properties": [
+        "name": ["type": "string"],
+        "price": ["type": "number"],
+      ],
+      "required": ["name"],
+    ]
+
+    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+  }
+
+  func testValidateDraft7() {
+    let schema: [String: Any]  = [
+      "$schema": "http://json-schema.org/draft-07/schema#",
+      "type": "object",
+      "properties": [
+        "name": ["type": "string"],
+        "price": ["type": "number"],
+      ],
+      "required": ["name"],
+    ]
+
+    XCTAssertTrue(validate(["name": "Eggs", "price": 34.99], schema: schema).valid)
+    XCTAssertFalse(validate(["price": 34.99], schema: schema).valid)
+  }
+}