feat: support argument types without primaryConstructor (#1518)

* feat: support argument types without primaryConstructor

* feat: refactor

* feat: throw exception if multiple constructors were found

Co-authored-by: samvazquez <[email protected]>

Author: samuelAndalon

generator/graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/exceptions/MultipleConstructorsFound.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2022 Expedia, Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.expediagroup.graphql.generator.exceptions
+
+import kotlin.reflect.KClass
+
+/**
+ * Thrown when multiple constructors of an input class were located.
+ */
+class MultipleConstructorsFound(klazz: KClass<*>) : GraphQLKotlinException("Invalid input object ${klazz.simpleName} - multiple public constructors found")

generator/graphql-kotlin-schema-generator/src/main/kotlin/com/expediagroup/graphql/generator/execution/convertArgumentValue.kt

@@ -16,6 +16,7 @@
 
 package com.expediagroup.graphql.generator.execution
 
+import com.expediagroup.graphql.generator.exceptions.MultipleConstructorsFound
 import com.expediagroup.graphql.generator.exceptions.PrimaryConstructorNotFound
 import com.expediagroup.graphql.generator.internal.extensions.getGraphQLName
 import com.expediagroup.graphql.generator.internal.extensions.getKClass
@@ -93,7 +94,17 @@ private fun convertValue(
  * the only thing left to parse is object maps into the nested Kotlin classes
  */
 private fun <T : Any> mapToKotlinObject(input: Map<String, *>, targetClass: KClass<T>): T {
-    val targetConstructor = targetClass.primaryConstructor ?: throw PrimaryConstructorNotFound(targetClass)
+
+    val targetConstructor = targetClass.primaryConstructor ?: run {
+        if (targetClass.constructors.size == 1) {
+            targetClass.constructors.first()
+        } else if (targetClass.constructors.size > 1) {
+            throw MultipleConstructorsFound(targetClass)
+        } else {
+            throw PrimaryConstructorNotFound(targetClass)
+        }
+    }
+
     val constructorParameters = targetConstructor.parameters
     // filter parameters that are actually in the input in order to rely on parameters default values
     // in target constructor

generator/graphql-kotlin-schema-generator/src/test/kotlin/com/expediagroup/graphql/generator/execution/ConvertArgumentValueTest.kt

@@ -17,6 +17,7 @@
 package com.expediagroup.graphql.generator.execution
 
 import com.expediagroup.graphql.generator.annotations.GraphQLName
+import com.expediagroup.graphql.generator.exceptions.MultipleConstructorsFound
 import com.expediagroup.graphql.generator.scalars.ID
 import graphql.schema.DataFetchingEnvironment
 import io.mockk.every
@@ -117,6 +118,39 @@ class ConvertArgumentValueTest {
         assertEquals("nested default value", castResult.nested?.value)
     }
 
+    @Test
+    fun `generic map object is parsed without using primary constructor`() {
+        val kParam = assertNotNull(TestFunctions::inputObjectNoPrimaryConstructor.findParameterByName("input"))
+        val result = convertArgumentValue(
+            "input",
+            kParam,
+            mapOf(
+                "input" to mapOf(
+                    "value" to "hello"
+                )
+            )
+        )
+
+        val castResult = assertIs<TestInputNoPrimaryConstructor>(result)
+        assertEquals("hello", castResult.value)
+    }
+
+    @Test
+    fun `exception is thrown when multiple constructors were found`() {
+        val kParam = assertNotNull(TestFunctions::inputObjectMultipleConstructors.findParameterByName("input"))
+        assertThrows<MultipleConstructorsFound> {
+            convertArgumentValue(
+                "input",
+                kParam,
+                mapOf(
+                    "input" to mapOf(
+                        "value" to "hello"
+                    )
+                )
+            )
+        }
+    }
+
     /**
      * this will be solved in Kotlin 1.7
      * "KotlinReflectionInternalError" when using `callBy` on constructor that has inline class parameters
@@ -241,6 +275,8 @@ class ConvertArgumentValueTest {
         fun enumInput(input: Foo): String = TODO()
         fun idInput(input: ID): String = TODO()
         fun inputObject(input: TestInput): String = TODO()
+        fun inputObjectNoPrimaryConstructor(input: TestInputNoPrimaryConstructor): String = TODO()
+        fun inputObjectMultipleConstructors(input: TestInputMultipleConstructors): String = TODO()
         fun inputObjectNested(input: TestInputNested): String = TODO()
         fun inputObjectNullableScalar(input: TestInputNullableScalar): String = TODO()
         fun inputObjectNotNullableScalar(input: TestInputNotNullableScalar): String = TODO()
@@ -257,8 +293,24 @@ class ConvertArgumentValueTest {
     class TestInputNestedType(val value: String = "nested default value")
     class TestInputNullableScalar(val foo: String? = null, val id: ID? = null)
     class TestInputNotNullableScalar(val foo: String, val id: ID = ID("1234"))
-
     class TestInputRenamed(@GraphQLName("bar") val foo: String)
+    class TestInputNoPrimaryConstructor {
+        val value: String
+        constructor(value: String) {
+            this.value = value
+        }
+    }
+    class TestInputMultipleConstructors {
+        val value: String
+
+        constructor() {
+            this.value = "Default Value"
+        }
+
+        constructor(value: String) {
+            this.value = value
+        }
+    }
 
     enum class Foo {
         BAR,