fix oneOf discriminator lookup in java okhttp-gson client (#11735)

bin/configs/java-okhttp-gson.yaml

@@ -6,3 +6,4 @@ templateDir: modules/openapi-generator/src/main/resources/Java
 additionalProperties:
   artifactId: petstore-okhttp-gson
   hideGenerationTimestamp: "true"
+  useOneOfDiscriminatorLookup: "true"

modules/openapi-generator/src/main/resources/Java/libraries/okhttp-gson/oneof_model.mustache

@@ -76,8 +76,11 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                     {{#discriminator}}
                     // use discriminator value for faster oneOf lookup
                     {{classname}} new{{classname}} = new {{classname}}();
-                    String discriminatorValue = elementAdapter.read(in).getAsJsonObject().get("{{{propertyBaseName}}}").getAsString();
+                    if (jsonObject.get("{{{propertyBaseName}}}") == null) {
-                    switch (discriminatorValue) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for {{classname}} as `{{{propertyBaseName}}}` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `{{{propertyBaseName}}}`
+                        switch (jsonObject.get("{{{propertyBaseName}}}").getAsString()) {
                         {{#mappedModels}}
                             case "{{{mappingName}}}":
                                 deserialized = adapter{{modelName}}.fromJsonTree(jsonObject);
@@ -85,7 +88,8 @@ public class {{classname}} extends AbstractOpenApiSchema{{#vendorExtensions.x-im
                                 return new{{classname}};
                         {{/mappedModels}}
                             default:
-                            log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for {{classname}}. Possible values:{{#mappedModels}} {{{mappingName}}}{{/mappedModels}}", discriminatorValue));
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for {{classname}}. Possible values:{{#mappedModels}} {{{mappingName}}}{{/mappedModels}}", jsonObject.get("{{{propertyBaseName}}}").getAsString()));
+                        }
                     }
 
                     {{/discriminator}}

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Mammal.java

@@ -113,6 +113,30 @@ public class Mammal extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    Mammal newMammal = new Mammal();
+                    if (jsonObject.get("className") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for Mammal as `className` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `className`
+                        switch (jsonObject.get("className").getAsString()) {
+                            case "Pig":
+                                deserialized = adapterPig.fromJsonTree(jsonObject);
+                                newMammal.setActualInstance(deserialized);
+                                return newMammal;
+                            case "whale":
+                                deserialized = adapterWhale.fromJsonTree(jsonObject);
+                                newMammal.setActualInstance(deserialized);
+                                return newMammal;
+                            case "zebra":
+                                deserialized = adapterZebra.fromJsonTree(jsonObject);
+                                newMammal.setActualInstance(deserialized);
+                                return newMammal;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for Mammal. Possible values: Pig whale zebra", jsonObject.get("className").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/NullableShape.java

@@ -104,6 +104,26 @@ public class NullableShape extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    NullableShape newNullableShape = new NullableShape();
+                    if (jsonObject.get("shapeType") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for NullableShape as `shapeType` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `shapeType`
+                        switch (jsonObject.get("shapeType").getAsString()) {
+                            case "Quadrilateral":
+                                deserialized = adapterQuadrilateral.fromJsonTree(jsonObject);
+                                newNullableShape.setActualInstance(deserialized);
+                                return newNullableShape;
+                            case "Triangle":
+                                deserialized = adapterTriangle.fromJsonTree(jsonObject);
+                                newNullableShape.setActualInstance(deserialized);
+                                return newNullableShape;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for NullableShape. Possible values: Quadrilateral Triangle", jsonObject.get("shapeType").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Pig.java

@@ -104,6 +104,26 @@ public class Pig extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    Pig newPig = new Pig();
+                    if (jsonObject.get("className") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for Pig as `className` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `className`
+                        switch (jsonObject.get("className").getAsString()) {
+                            case "BasquePig":
+                                deserialized = adapterBasquePig.fromJsonTree(jsonObject);
+                                newPig.setActualInstance(deserialized);
+                                return newPig;
+                            case "DanishPig":
+                                deserialized = adapterDanishPig.fromJsonTree(jsonObject);
+                                newPig.setActualInstance(deserialized);
+                                return newPig;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for Pig. Possible values: BasquePig DanishPig", jsonObject.get("className").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Quadrilateral.java

@@ -104,6 +104,26 @@ public class Quadrilateral extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    Quadrilateral newQuadrilateral = new Quadrilateral();
+                    if (jsonObject.get("quadrilateralType") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for Quadrilateral as `quadrilateralType` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `quadrilateralType`
+                        switch (jsonObject.get("quadrilateralType").getAsString()) {
+                            case "ComplexQuadrilateral":
+                                deserialized = adapterComplexQuadrilateral.fromJsonTree(jsonObject);
+                                newQuadrilateral.setActualInstance(deserialized);
+                                return newQuadrilateral;
+                            case "SimpleQuadrilateral":
+                                deserialized = adapterSimpleQuadrilateral.fromJsonTree(jsonObject);
+                                newQuadrilateral.setActualInstance(deserialized);
+                                return newQuadrilateral;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for Quadrilateral. Possible values: ComplexQuadrilateral SimpleQuadrilateral", jsonObject.get("quadrilateralType").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Shape.java

@@ -104,6 +104,26 @@ public class Shape extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    Shape newShape = new Shape();
+                    if (jsonObject.get("shapeType") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for Shape as `shapeType` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `shapeType`
+                        switch (jsonObject.get("shapeType").getAsString()) {
+                            case "Quadrilateral":
+                                deserialized = adapterQuadrilateral.fromJsonTree(jsonObject);
+                                newShape.setActualInstance(deserialized);
+                                return newShape;
+                            case "Triangle":
+                                deserialized = adapterTriangle.fromJsonTree(jsonObject);
+                                newShape.setActualInstance(deserialized);
+                                return newShape;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for Shape. Possible values: Quadrilateral Triangle", jsonObject.get("shapeType").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/ShapeOrNull.java

@@ -104,6 +104,26 @@ public class ShapeOrNull extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    ShapeOrNull newShapeOrNull = new ShapeOrNull();
+                    if (jsonObject.get("shapeType") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for ShapeOrNull as `shapeType` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `shapeType`
+                        switch (jsonObject.get("shapeType").getAsString()) {
+                            case "Quadrilateral":
+                                deserialized = adapterQuadrilateral.fromJsonTree(jsonObject);
+                                newShapeOrNull.setActualInstance(deserialized);
+                                return newShapeOrNull;
+                            case "Triangle":
+                                deserialized = adapterTriangle.fromJsonTree(jsonObject);
+                                newShapeOrNull.setActualInstance(deserialized);
+                                return newShapeOrNull;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for ShapeOrNull. Possible values: Quadrilateral Triangle", jsonObject.get("shapeType").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/main/java/org/openapitools/client/model/Triangle.java

@@ -113,6 +113,30 @@ public class Triangle extends AbstractOpenApiSchema {
                     Object deserialized = null;
                     JsonObject jsonObject = elementAdapter.read(in).getAsJsonObject();
 
+                    // use discriminator value for faster oneOf lookup
+                    Triangle newTriangle = new Triangle();
+                    if (jsonObject.get("triangleType") == null) {
+                        log.log(Level.WARNING, "Failed to lookup discriminator value for Triangle as `triangleType` was not found in the payload or the payload is empty.");
+                    } else  {
+                        // look up the discriminator value in the field `triangleType`
+                        switch (jsonObject.get("triangleType").getAsString()) {
+                            case "EquilateralTriangle":
+                                deserialized = adapterEquilateralTriangle.fromJsonTree(jsonObject);
+                                newTriangle.setActualInstance(deserialized);
+                                return newTriangle;
+                            case "IsoscelesTriangle":
+                                deserialized = adapterIsoscelesTriangle.fromJsonTree(jsonObject);
+                                newTriangle.setActualInstance(deserialized);
+                                return newTriangle;
+                            case "ScaleneTriangle":
+                                deserialized = adapterScaleneTriangle.fromJsonTree(jsonObject);
+                                newTriangle.setActualInstance(deserialized);
+                                return newTriangle;
+                            default:
+                                log.log(Level.WARNING, String.format("Failed to lookup discriminator value `%s` for Triangle. Possible values: EquilateralTriangle IsoscelesTriangle ScaleneTriangle", jsonObject.get("triangleType").getAsString()));
+                        }
+                    }
+
                     int match = 0;
                     TypeAdapter actualAdapter = elementAdapter;
 

samples/client/petstore/java/okhttp-gson/src/test/java/org/openapitools/client/JSONTest.java

@@ -364,6 +364,65 @@ public class JSONTest {
         }
     }
 
+    /**
+     * Validate a oneOf schema can be deserialized into the expected class.
+     * The oneOf schema has a discriminator. 
+     */
+    @Test
+    public void testOneOfSchemaWithDiscriminator() throws Exception {
+        {
+            String str = "{ \"className\": \"whale\", \"hasBaleen\": false, \"hasTeeth\": false }";
+
+            // make sure deserialization works for pojo object
+            Whale w = json.getGson().fromJson(str, Whale.class);
+            assertEquals(w.getClassName(), "whale");
+            assertEquals(w.getHasBaleen(), false);
+            assertEquals(w.getHasTeeth(), false);
+
+            Mammal o = json.getGson().fromJson(str, Mammal.class);
+            assertTrue(o.getActualInstance() instanceof Whale);
+            Whale inst = (Whale) o.getActualInstance();
+            assertEquals(inst.getClassName(), "whale");
+            assertEquals(inst.getHasBaleen(), false);
+            assertEquals(inst.getHasTeeth(), false);
+            assertEquals(json.getGson().toJson(inst), "{\"hasBaleen\":false,\"hasTeeth\":false,\"className\":\"whale\"}");
+            assertEquals(inst.toJson(), "{\"hasBaleen\":false,\"hasTeeth\":false,\"className\":\"whale\"}");
+            assertEquals(json.getGson().toJson(o), "{\"hasBaleen\":false,\"hasTeeth\":false,\"className\":\"whale\"}");
+            assertEquals(o.toJson(), "{\"hasBaleen\":false,\"hasTeeth\":false,\"className\":\"whale\"}");
+
+            String str2 = "{ \"className\": \"zebra\", \"type\": \"plains\" }";
+
+            // make sure deserialization works for pojo object
+            Zebra z = Zebra.fromJson(str2);
+            assertEquals(z.toJson(), "{\"className\":\"zebra\",\"type\":\"plains\"}");
+
+            Mammal o2 = json.getGson().fromJson(str2, Mammal.class);
+            assertTrue(o2.getActualInstance() instanceof Zebra);
+            Zebra inst2 = (Zebra) o2.getActualInstance();
+            assertEquals(json.getGson().toJson(inst2), "{\"className\":\"zebra\",\"type\":\"plains\"}");
+            assertEquals(inst2.toJson(), "{\"className\":\"zebra\",\"type\":\"plains\"}");
+            assertEquals(json.getGson().toJson(o2), "{\"className\":\"zebra\",\"type\":\"plains\"}");
+            assertEquals(o2.toJson(), "{\"className\":\"zebra\",\"type\":\"plains\"}");
+        }
+        {
+            // incorrect payload results in exception
+            String str = "{ \"cultivar\": \"golden delicious\", \"mealy\": false, \"garbage_prop\": \"abc\" }";
+            Exception exception = assertThrows(com.google.gson.JsonSyntaxException.class, () -> {
+                Mammal o = json.getGson().fromJson(str, Mammal.class);
+            });
+            assertTrue(exception.getMessage().contains("Failed deserialization for Mammal: 0 classes match result, expected 1. JSON: {\"cultivar\":\"golden delicious\",\"mealy\":false,\"garbage_prop\":\"abc\"}"));
+        }
+        {
+            // Try to deserialize empty object. This should fail 'oneOf' because none will match
+            // whale or zebra.
+            String str = "{ }";
+            Exception exception = assertThrows(com.google.gson.JsonSyntaxException.class, () -> {
+                json.getGson().fromJson(str, Mammal.class);
+            });
+            assertTrue(exception.getMessage().contains("Failed deserialization for Mammal: 0 classes match result, expected 1"));
+        }
+    }
+
     /**
      * Validate a oneOf schema can be deserialized into the expected class.
      * The oneOf schema does not have a discriminator.