Support underlying type extraction for Kotlin value classes in KSP codegen (#1404)

Author: jbl428

querydsl-examples/querydsl-example-ksp-codegen/src/main/kotlin/com/querydsl/example/ksp/Email.kt

@@ -0,0 +1,6 @@
+package com.querydsl.example.ksp
+
+@JvmInline
+value class Email(
+    val value: String
+)

querydsl-examples/querydsl-example-ksp-codegen/src/main/kotlin/com/querydsl/example/ksp/Person.kt

@@ -9,6 +9,7 @@ class Person(
     @Id
     val id: Int,
     val name: String,
+    val email: Email,
 
     @OneToMany(mappedBy = "owner")
     val cats: List<Cat>? = null,

querydsl-examples/querydsl-example-ksp-codegen/src/test/kotlin/Tests.kt

@@ -2,12 +2,12 @@ import com.querydsl.example.ksp.Bear
 import com.querydsl.example.ksp.Cat
 import com.querydsl.example.ksp.CatType
 import com.querydsl.example.ksp.Dog
+import com.querydsl.example.ksp.Email
 import com.querydsl.example.ksp.Person
 import com.querydsl.example.ksp.QBear
 import com.querydsl.example.ksp.QBearSimplifiedProjection
 import com.querydsl.example.ksp.QCat
 import com.querydsl.example.ksp.QDog
-import com.querydsl.example.ksp.QGeolocation
 import com.querydsl.example.ksp.QMyShape
 import com.querydsl.example.ksp.QPerson
 import com.querydsl.example.ksp.QPersonClassDTO
@@ -33,7 +33,7 @@ class Tests {
         run {
             val em = emf.createEntityManager()
             em.transaction.begin()
-            em.persist(Person(424, "John Smith"))
+            em.persist(Person(424, "John Smith", Email("[email protected]")))
             em.transaction.commit()
             em.close()
         }
@@ -44,7 +44,7 @@ class Tests {
             val q = QPerson.person
             val person = queryFactory
                 .selectFrom(q)
-                .where(q.name.eq("John Smith"))
+                .where(q.name.eq("John Smith"), q.email.eq("[email protected]"))
                 .fetchOne()
             if (person == null) {
                 fail<Any>("No person was returned")
@@ -62,7 +62,7 @@ class Tests {
         run {
             val em = emf.createEntityManager()
             em.transaction.begin()
-            val catOwner = Person(425, "Percy Bysshe Catownerly")
+            val catOwner = Person(425, "Percy Bysshe Catownerly", Email("[email protected]"))
             em.persist(catOwner)
             em.persist(Cat(103, "Samuel Taylor Cattingridge", false, "Not so fluffy", catOwner, CatType.MAINE_COON))
             em.transaction.commit()
@@ -132,7 +132,7 @@ class Tests {
         run {
             val em = emf.createEntityManager()
             em.transaction.begin()
-            em.persist(Person(424, "John Smith"))
+            em.persist(Person(424, "John Smith", Email("[email protected]")))
             em.transaction.commit()
             em.close()
         }

querydsl-tooling/querydsl-ksp-codegen/src/main/kotlin/com/querydsl/ksp/codegen/TypeExtractor.kt

@@ -14,17 +14,30 @@ class TypeExtractor(
     private val annotations: Sequence<KSAnnotation>
 ) {
     fun extract(type: KSType): QPropertyType {
-        val declaration = type.declaration
-        if (declaration is KSTypeAlias) {
-            val innerType = declaration.type.resolve()
-            return extract(innerType)
-        } else {
-            return userType(type)
-                ?: parameterType(type)
-                ?: simpleType(type)
-                ?: referenceType(type)
-                ?: collectionType(type)
-                ?: fallbackType(type)
+        when (val declaration = type.declaration) {
+            is KSClassDeclaration if declaration.modifiers.contains(Modifier.VALUE) -> {
+                val wrappedType = declaration
+                    .primaryConstructor
+                    ?.parameters
+                    ?.firstOrNull()
+                    ?.type
+                    ?.resolve()
+                    ?: throwError("Cannot resolve type: $declaration")
+
+                return extract(wrappedType)
+            }
+            is KSTypeAlias -> {
+                val innerType = declaration.type.resolve()
+                return extract(innerType)
+            }
+            else -> {
+                return userType(type)
+                    ?: parameterType(type)
+                    ?: simpleType(type)
+                    ?: referenceType(type)
+                    ?: collectionType(type)
+                    ?: fallbackType(type)
+            }
         }
     }