Implementation of #436 (#437)

Co-authored-by: Florian Wiesner <Florian [email protected]>

Author: FWiesner

src/main/java/com/networknt/schema/AllOfValidator.java

@@ -70,7 +70,10 @@ public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String
                                 registerAndMergeDiscriminator(currentDiscriminatorContext, discriminator, parentSchema, at);
                                 // now we have to check whether we have hit the right target
                                 final String discriminatorPropertyName = discriminator.get("propertyName").asText();
-                                final String discriminatorPropertyValue = node.get(discriminatorPropertyName).textValue();
+                                final JsonNode discriminatorNode = node.get(discriminatorPropertyName);
+                                final String discriminatorPropertyValue = discriminatorNode == null
+                                        ? null
+                                        : discriminatorNode.textValue();
 
                                 final JsonSchema jsonSchema = parentSchema;
                                 checkDiscriminatorMatch(

src/main/java/com/networknt/schema/AnyOfValidator.java

@@ -65,7 +65,7 @@ public Set<ValidationMessage> validate(JsonNode node, JsonNode rootNode, String
                 if (schema.getValidators().containsKey(typeValidatorName)) {
                     TypeValidator typeValidator = ((TypeValidator) schema.getValidators().get(typeValidatorName));
                     //If schema has type validator and node type doesn't match with schemaType then ignore it
-                    //For union type, it is must to call TypeValidator
+                    //For union type, it is a must to call TypeValidator
                     if (typeValidator.getSchemaType() != JsonType.UNION && !typeValidator.equalsToSchemaType(node)) {
                         allErrors.add(buildValidationMessage(at, typeValidator.getSchemaType().toString()));
                         continue;

src/main/java/com/networknt/schema/BaseJsonValidator.java

@@ -195,6 +195,11 @@ protected static void checkDiscriminatorMatch(final ValidationContext.Discrimina
                                                   final ObjectNode discriminator,
                                                   final String discriminatorPropertyValue,
                                                   final JsonSchema jsonSchema) {
+        if (discriminatorPropertyValue == null) {
+            currentDiscriminatorContext.markMatch();
+            return;
+        }
+
         final JsonNode discriminatorMapping = discriminator.get("mapping");
         if (null == discriminatorMapping) {
             checkForImplicitDiscriminatorMappingMatch(currentDiscriminatorContext,

src/main/java/com/networknt/schema/JsonSchema.java

@@ -264,7 +264,8 @@ public Set<ValidationMessage> validate(JsonNode jsonNode, JsonNode rootNode, Str
                     }
 
                     final String discriminatorPropertyName = discriminatorToUse.get("propertyName").asText();
-                    final String discriminatorPropertyValue = jsonNode.get(discriminatorPropertyName).asText();
+                    final JsonNode discriminatorNode = jsonNode.get(discriminatorPropertyName);
+                    final String discriminatorPropertyValue = discriminatorNode == null ? null : discriminatorNode.asText();
                     checkDiscriminatorMatch(discriminatorContext,
                                             discriminatorToUse,
                                             discriminatorPropertyValue,

src/test/resources/openapi3/discriminator.json

@@ -277,6 +277,75 @@
                     "@type": "Bathroom"
                 },
                 "valid": false
+            },
+            {
+                "description": "discriminator missing - falling back to default validation with failure as @type is mandatory",
+                "data": {
+                },
+                "valid": false
+            }
+        ]
+    },
+    {
+        "description": "absent discriminator value as discriminator marked as non-mandatory (which is against OAS3 recommendations)",
+        "schema": {
+            "anyOf": [
+                {
+                    "$ref": "#/components/schemas/Room"
+                },
+                {
+                    "$ref": "#/components/schemas/BedRoom"
+                }
+            ],
+            "components": {
+                "schemas": {
+                    "Room": {
+                        "type": "object",
+                        "properties": {
+                            "intOrStringType": {
+                                "type": "integer"
+                            }
+                        },
+                        "discriminator": {
+                            "propertyName": "@type",
+                            "mapping": {
+                                "bed": "#/components/schemas/BedRoom"
+                            }
+                        }
+                    },
+                    "BedRoom": {
+                        "type": "object",
+                        "allOf": [
+                            {
+                                "$ref": "#/components/schemas/Room"
+                            },
+                            {
+                                "type": "object",
+                                "properties": {
+                                    "intOrStringType": {
+                                        "type": "string"
+                                    }
+                                }
+                            }
+                        ]
+                    }
+                }
+            }
+        },
+        "tests": [
+            {
+                "description": "discriminator missing - falling back to default anyOf behavior",
+                "data": {
+                    "intOrStringType": 4
+                },
+                "valid": true
+            },
+            {
+                "description": "discriminator missing - with constructed schema conflict",
+                "data": {
+                    "intOrStringType": "cannot match due to allOf"
+                },
+                "valid": false
             }
         ]
     },