Fix __typename Introspection not Working on Introspection Types

ballerina-tests/tests/10_introspection_queries.bal

@@ -66,13 +66,13 @@ isolated function testIntrospectionQueryWithMissingSelection() returns error? {
     groups: ["introspection"]
 }
 isolated function testInvalidSchemaIntrospectionField() returns error? {
-    string graphqlUrl ="http://localhost:9091/records";
+    string graphqlUrl = "http://localhost:9091/records";
     string document = "{ profile(id: 1) { name __schema { queryType { name } } } }";
     json actualResult = check getJsonPayloadFromBadRequest(graphqlUrl, document);
     json expectedResult = {
         errors: [
             {
-                message: string`Cannot query field "__schema" on type "Person".`,
+                message: string `Cannot query field "__schema" on type "Person".`,
                 locations: [
                     {
                         line: 1,
@@ -89,7 +89,7 @@ isolated function testInvalidSchemaIntrospectionField() returns error? {
     groups: ["introspection"]
 }
 isolated function testQueryTypeIntrospection() returns error? {
-    string graphqlUrl ="http://localhost:9091/validation";
+    string graphqlUrl = "http://localhost:9091/validation";
     string document = "{ __schema { queryType { kind fields { name } } } }";
     json actualResult = check getJsonPayloadFromService(graphqlUrl, document);
     json expectedResult = check getJsonContentFromFile("query_type_introspection.json");
@@ -100,7 +100,7 @@ isolated function testQueryTypeIntrospection() returns error? {
     groups: ["introspection"]
 }
 isolated function testMutationTypeIntrospection() returns error? {
-    string graphqlUrl ="http://localhost:9091/mutations";
+    string graphqlUrl = "http://localhost:9091/mutations";
     string document = "{ __schema { mutationType { kind fields { name } } } }";
     json actualResult = check getJsonPayloadFromService(graphqlUrl, document);
     json expectedResult = check getJsonContentFromFile("mutation_type_introspection.json");
@@ -122,7 +122,7 @@ isolated function testComplexIntrospectionQueryWithOtherFields() returns error?
     groups: ["introspection"]
 }
 isolated function testEnumValueIntrospection() returns error? {
-    string graphqlUrl ="http://localhost:9092/service_objects";
+    string graphqlUrl = "http://localhost:9092/service_objects";
     string document = "{ __schema { types { enumValues } } }";
     json actualResult = check getJsonPayloadFromBadRequest(graphqlUrl, document);
     json expectedResult = check getJsonContentFromFile("enum_value_introspection.json");
@@ -133,7 +133,7 @@ isolated function testEnumValueIntrospection() returns error? {
     groups: ["introspection", "typename"]
 }
 isolated function testTypeNameIntrospectionOnOperation() returns error? {
-    string graphqlUrl ="http://localhost:9091/records";
+    string graphqlUrl = "http://localhost:9091/records";
     string document = "{ __typename }";
     json actualResult = check getJsonPayloadFromService(graphqlUrl, document);
     json expectedResult = {
@@ -148,7 +148,7 @@ isolated function testTypeNameIntrospectionOnOperation() returns error? {
     groups: ["introspection", "typename"]
 }
 isolated function testTypeNameIntrospectionOnRecordTypes() returns error? {
-    string graphqlUrl ="http://localhost:9091/records";
+    string graphqlUrl = "http://localhost:9091/records";
     string document = "{ detective { __typename } }";
     json actualResult = check getJsonPayloadFromService(graphqlUrl, document);
     json expectedResult = {
@@ -165,7 +165,7 @@ isolated function testTypeNameIntrospectionOnRecordTypes() returns error? {
     groups: ["introspection", "validation", "typename"]
 }
 isolated function testQueryingSubfieldsOnTypeName() returns error? {
-    string graphqlUrl ="http://localhost:9091/records";
+    string graphqlUrl = "http://localhost:9091/records";
     string document = "{ detective { __typename { name } } }";
     json actualResult = check getJsonPayloadFromBadRequest(graphqlUrl, document);
     json expectedResult = {
@@ -243,13 +243,13 @@ isolated function testIntrospectionOnServiceWithInputObjects() returns error? {
     groups: ["introspection", "typename", "validation"]
 }
 isolated function testTypeNameIntrospectionOnScalar() returns error? {
-    string graphqlUrl ="http://localhost:9091/validation";
+    string graphqlUrl = "http://localhost:9091/validation";
     string document = "{ name { __typename } }";
     json actualResult = check getJsonPayloadFromBadRequest(graphqlUrl, document);
     json expectedResult = {
         errors: [
             {
-                message: string`Field "name" must not have a selection since type "String!" has no subfields.`,
+                message: string `Field "name" must not have a selection since type "String!" has no subfields.`,
                 locations: [
                     {
                         line: 1,
@@ -300,9 +300,9 @@ isolated function testTypeIntrospection() returns error? {
 }
 isolated function testTypeIntrospectionOnNonExistingType() returns error? {
     string graphqlUrl = "http://localhost:9091/records";
-    string document = string`{ __type(name: "INVALID") { kind } }`;
+    string document = string `{ __type(name: "INVALID") { kind } }`;
     json result = check getJsonPayloadFromService(graphqlUrl, document);
-    json expectedPayload = { data: { __type: null } };
+    json expectedPayload = {data: {__type: null}};
     assertJsonValuesWithOrder(result, expectedPayload);
 }
 
@@ -311,12 +311,12 @@ isolated function testTypeIntrospectionOnNonExistingType() returns error? {
 }
 isolated function testTypeIntrospectionWithoutFields() returns error? {
     string graphqlUrl = "http://localhost:9091/records";
-    string document = string`{ __type(name: "Person") }`;
+    string document = string `{ __type(name: "Person") }`;
     json result = check getJsonPayloadFromBadRequest(graphqlUrl, document);
     json expectedPayload = {
         errors: [
             {
-                message: string`Field "__type" of type "__Type" must have a selection of subfields. Did you mean "__type { ... }"?`,
+                message: string `Field "__type" of type "__Type" must have a selection of subfields. Did you mean "__type { ... }"?`,
                 locations: [
                     {
                         line: 1,
@@ -419,3 +419,36 @@ isolated function testTypeIntrospectionWithAlias() returns error? {
     json expectedPayload = check getJsonContentFromFile("type_introspection_with_alias.json");
     assertJsonValuesWithOrder(actualPayload, expectedPayload);
 }
+
+@test:Config {
+    groups: ["introspection", "type", "typename"]
+}
+isolated function testTypeNameIntrospectionOnTypeRecord() returns error? {
+    string graphqlUrl = "http://localhost:9091/records";
+    string document = check getGraphQLDocumentFromFile("typename_introspection_on_type_record.graphql");
+    json actualPayload = check getJsonPayloadFromService(graphqlUrl, document);
+    json expectedPayload = check getJsonContentFromFile("typename_introspection_on_type_record.json");
+    assertJsonValuesWithOrder(actualPayload, expectedPayload);
+}
+
+@test:Config {
+    groups: ["introspection", "type", "typename"]
+}
+isolated function testTypeNameIntrospectionOnSchemaIntrospection() returns error? {
+    string graphqlUrl = "http://localhost:9091/validation";
+    string document = check getGraphQLDocumentFromFile("typename_introspection_on_schema_introspection.graphql");
+    json actualPayload = check getJsonPayloadFromService(graphqlUrl, document);
+    json expectedPayload = check getJsonContentFromFile("typename_introspection_on_schema_introspection.json");
+    assertJsonValuesWithOrder(actualPayload, expectedPayload);
+}
+
+@test:Config {
+    groups: ["introspection", "field", "typename"]
+}
+isolated function testTypeNameIntrospectionOnField() returns error? {
+    string graphqlUrl = "http://localhost:9091/records";
+    string document = check getGraphQLDocumentFromFile("typename_introspection_on_field.graphql");
+    json actualPayload = check getJsonPayloadFromService(graphqlUrl, document);
+    json expectedPayload = check getJsonContentFromFile("typename_introspection_on_field.json");
+    assertJsonValuesWithOrder(actualPayload, expectedPayload);
+}

ballerina-tests/tests/resources/documents/typename_introspection_on_field.graphql

@@ -0,0 +1,9 @@
+{
+    __type(name: "Person") {
+        name
+        fields {
+            name
+            __typename
+        }
+    }
+}

ballerina-tests/tests/resources/documents/typename_introspection_on_schema_introspection.graphql

@@ -0,0 +1,8 @@
+{
+  __schema {
+    types {
+      name
+      __typename
+    }
+  }
+}

ballerina-tests/tests/resources/documents/typename_introspection_on_type_record.graphql

@@ -0,0 +1,5 @@
+{
+    __type(name: "Person") {
+        __typename
+    }
+}

ballerina-tests/tests/resources/expected_results/typename_introspection_on_field.json

@@ -0,0 +1,21 @@
+{
+    "data": {
+        "__type": {
+            "name": "Person",
+            "fields": [
+                {
+                    "name": "name",
+                    "__typename": "__Field"
+                },
+                {
+                    "name": "age",
+                    "__typename": "__Field"
+                },
+                {
+                    "name": "address",
+                    "__typename": "__Field"
+                }
+            ]
+        }
+    }
+}

ballerina-tests/tests/resources/expected_results/typename_introspection_on_schema_introspection.json

@@ -0,0 +1,56 @@
+{
+    "data": {
+        "__schema": {
+            "types": [
+                {
+                    "name": "__Field",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__TypeKind",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "Query",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__Schema",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__Type",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__EnumValue",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__DirectiveLocation",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "String",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__InputValue",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "Boolean",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "Int",
+                    "__typename": "__Type"
+                },
+                {
+                    "name": "__Directive",
+                    "__typename": "__Type"
+                }
+            ]
+        }
+    }
+}

ballerina-tests/tests/resources/expected_results/typename_introspection_on_type_record.json

@@ -0,0 +1,7 @@
+{
+    "data": {
+        "__type": {
+            "__typename": "__Type"
+        }
+    }
+}

ballerina/introspection_executor.bal

@@ -56,6 +56,11 @@ class IntrospectionExecutor {
     }
 
     isolated function getValueFromFieldNode(parser:FieldNode fieldNode, map<anydata> parentValue, Data result) {
+        string fieldName = fieldNode.getName();
+        if fieldName == TYPE_NAME_FIELD {
+            result[fieldNode.getAlias()] = getTypeNameFromValue(parentValue);
+            return;
+        }
         anydata fieldValue = parentValue.get(fieldNode.getName());
         self.getFieldValue(fieldNode, fieldValue, result);
     }

changelog.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Fixed
 - [[#3865] Fix Incomplete Type Info Given in Compiler Errors Issued from GraphQL Compiler Plugin](https://github.com/ballerina-platform/ballerina-standard-library/issues/3865)
 - [[#3721] Fix Passing Incorrect Values when a Resolver Method has an Enum as Input Parameter](https://github.com/ballerina-platform/ballerina-standard-library/issues/3721)
+- [[#4038] Fix `__typename` Introspection not Working on Introspection Types](https://github.com/ballerina-platform/ballerina-standard-library/issues/4038)
 
 ### Changed
 - [[#3430] Parallelise GraphQL Document Validation](https://github.com/ballerina-platform/ballerina-standard-library/issues/3430)