feat: new hook for modifying object types

src/main/kotlin/com/expedia/graphql/generator/TypeBuilder.kt

@@ -23,9 +23,12 @@ internal open class TypeBuilder constructor(protected val generator: SchemaGener
         val graphQLType = hookGraphQLType
             ?: generator.scalarType(type, annotatedAsID)
             ?: objectFromReflection(type, inputType)
-        val typeWithNullityTakenIntoAccount = graphQLType.wrapInNonNull(type)
-        config.hooks.didGenerateGraphQLType(type, typeWithNullityTakenIntoAccount)
-        return typeWithNullityTakenIntoAccount
+
+        val typeWithNullability = graphQLType.wrapInNonNull(type)
+
+        config.hooks.didGenerateGraphQLType(type, typeWithNullability)
+
+        return typeWithNullability
     }
 
     internal fun objectFromReflection(type: KType, inputType: Boolean): GraphQLType {
@@ -39,12 +42,14 @@ internal open class TypeBuilder constructor(protected val generator: SchemaGener
         val kClass = type.getKClass()
         val graphQLType = getGraphQLType(kClass, inputType, type)
 
-        if (graphQLType !is GraphQLTypeReference) {
-            val kGraphQLType = KGraphQLType(kClass, graphQLType)
+        val modifiedGraphQLType = config.hooks.willAddGraphQLTypeToSchema(type, graphQLType)
+
+        if (modifiedGraphQLType !is GraphQLTypeReference) {
+            val kGraphQLType = KGraphQLType(kClass, modifiedGraphQLType)
             state.cache.put(cacheKey, kGraphQLType)
         }
 
-        return graphQLType
+        return modifiedGraphQLType
     }
 
     private fun getGraphQLType(kClass: KClass<*>, inputType: Boolean, type: KType): GraphQLType = when {

src/main/kotlin/com/expedia/graphql/hooks/SchemaGeneratorHooks.kt

@@ -28,6 +28,12 @@ interface SchemaGeneratorHooks {
     @Suppress("Detekt.FunctionOnlyReturningConstant")
     fun willGenerateGraphQLType(type: KType): GraphQLType? = null
 
+    /**
+     * Called after using reflection to generate the graphql object type but before returning it to the schema builder.
+     * This allows for modifying the type info, like description or directives
+     */
+    fun willAddGraphQLTypeToSchema(type: KType, generatedType: GraphQLType): GraphQLType = generatedType
+
     /**
      * Called before resolving a KType to the GraphQL type.
      * This allows for a custom resolver on how to extract wrapped values, like in a CompletableFuture.

src/test/kotlin/com/expedia/graphql/hooks/SchemaGeneratorHooksTest.kt

@@ -123,6 +123,32 @@ class SchemaGeneratorHooksTest {
         assertEquals("SomeData!", hooks.lastSeenGeneratedType?.deepName)
     }
 
+    @Test
+    fun `calls hook before adding type to schema`() {
+        class MockSchemaGeneratorHooks : SchemaGeneratorHooks {
+            var hookCalled = false
+
+            override fun willAddGraphQLTypeToSchema(type: KType, generatedType: GraphQLType): GraphQLType {
+                hookCalled = true
+                return when {
+                    generatedType is GraphQLObjectType && generatedType.name == "SomeData" -> GraphQLObjectType.Builder(generatedType).description("My custom description").build()
+                    else -> generatedType
+                }
+            }
+        }
+
+        val hooks = MockSchemaGeneratorHooks()
+        val schema = toSchema(
+            queries = listOf(TopLevelObject(TestQuery())),
+            config = getTestSchemaConfigWithHooks(hooks)
+        )
+        assertTrue(hooks.hookCalled)
+
+        val type = schema.getObjectType("SomeData")
+        assertNotNull(type)
+        assertEquals(expected = "My custom description", actual = type.description)
+    }
+
     @Test
     fun `calls hook before adding query to schema`() {
         class MockSchemaGeneratorHooks : SchemaGeneratorHooks {