issue #1405 Fix serialization of subqueries (#1406)

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

Author: kamilkrzywanski

querydsl-libraries/querydsl-core/src/main/java/com/querydsl/core/support/FetchableQueryBase.java

@@ -32,6 +32,9 @@
  */
 public abstract class FetchableQueryBase<T, Q extends FetchableQueryBase<T, Q>> extends QueryBase<Q>
     implements Fetchable<T> {
+  protected FetchableQueryBase() {
+    super();
+  }
 
   public FetchableQueryBase(QueryMixin<Q> queryMixin) {
     super(queryMixin);

querydsl-libraries/querydsl-core/src/main/java/com/querydsl/core/support/QueryBase.java

@@ -34,6 +34,10 @@ public abstract class QueryBase<Q extends QueryBase<Q>> {
 
   protected final QueryMixin<Q> queryMixin;
 
+  protected QueryBase() {
+    this.queryMixin = null;
+  }
+
   public QueryBase(QueryMixin<Q> queryMixin) {
     this.queryMixin = queryMixin;
   }

querydsl-libraries/querydsl-jpa/src/main/java/com/querydsl/jpa/JPAQueryBase.java

@@ -15,12 +15,18 @@
 
 import com.querydsl.core.QueryMetadata;
 import com.querydsl.core.support.FetchableSubQueryBase;
+import com.querydsl.core.support.QueryBase;
 import com.querydsl.core.types.CollectionExpression;
 import com.querydsl.core.types.EntityPath;
 import com.querydsl.core.types.MapExpression;
 import com.querydsl.core.types.Path;
 import com.querydsl.core.types.Predicate;
 import com.querydsl.core.types.dsl.Expressions;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serial;
+import java.lang.reflect.Field;
 
 /**
  * {@code JPAQueryBase} is a base Query class for JPA queries
@@ -32,9 +38,9 @@
 public abstract class JPAQueryBase<T, Q extends JPAQueryBase<T, Q>>
     extends FetchableSubQueryBase<T, Q> implements JPQLQuery<T> {
 
-  protected final JPAQueryMixin<Q> queryMixin;
+  protected final transient JPAQueryMixin<Q> queryMixin;
 
-  private final JPQLTemplates templates;
+  private final transient JPQLTemplates templates;
 
   @SuppressWarnings("unchecked")
   public JPAQueryBase(QueryMetadata md, JPQLTemplates templates) {
@@ -224,4 +230,32 @@ public String toString() {
 
   @Override
   public abstract Q clone();
+
+  @Serial
+  private void writeObject(ObjectOutputStream oos) throws IOException {
+    oos.writeObject(getMetadata());
+  }
+
+  @Serial
+  private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
+    QueryMetadata metadata = (QueryMetadata) ois.readObject();
+    JPAQueryMixin<Q> queryMixinValue = new JPAQueryMixin<>(metadata);
+    @SuppressWarnings("unchecked")
+    Q self = (Q) this;
+    queryMixinValue.setSelf(self);
+    try {
+      setFinalFieldValue(JPAQueryBase.class, "templates", JPQLTemplates.DEFAULT);
+      setFinalFieldValue(JPAQueryBase.class, "queryMixin", queryMixinValue);
+      setFinalFieldValue(QueryBase.class, "queryMixin", queryMixinValue);
+    } catch (NoSuchFieldException | IllegalAccessException e) {
+      throw new RuntimeException(e);
+    }
+  }
+
+  private void setFinalFieldValue(Class<?> type, String fieldName, Object value)
+      throws NoSuchFieldException, IllegalAccessException {
+    Field field = type.getDeclaredField(fieldName);
+    field.setAccessible(true);
+    field.set(this, value);
+  }
 }

querydsl-libraries/querydsl-jpa/src/test/java/com/querydsl/jpa/SubQueryTest.java

@@ -19,8 +19,11 @@
 import static com.querydsl.jpa.JPAExpressions.selectFrom;
 import static com.querydsl.jpa.JPAExpressions.selectOne;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.assertEquals;
 
 import com.querydsl.core.domain.QCat;
+import com.querydsl.core.testutil.Serialization;
+import com.querydsl.jpa.domain.Cat;
 import com.querydsl.jpa.domain.QEmployee;
 import com.querydsl.jpa.domain.QUser;
 import org.junit.Test;
@@ -193,4 +196,10 @@ public void indexOf() {
   //                query.toString().replace("\n", " "));
   //    }
 
+  @Test
+  public void subQueryShouldBeSerialized() {
+    JPQLSubQuery<Cat> subQuery = select(cat).from(cat).where(cat.alive.isTrue());
+    JPQLSubQuery<Cat> deserializationResult = Serialization.serialize(subQuery);
+    assertEquals(subQuery, deserializationResult);
+  }
 }