FIX: use outer join on "is null" check

src/test/java/org/tests/query/TestOuterJoin.java

@@ -0,0 +1,197 @@
+package org.tests.query;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assert.*;
+
+import java.util.List;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.tests.model.basic.Customer;
+import org.tests.model.basic.Order;
+import org.tests.model.basic.ResetBasicData;
+
+import io.ebean.BaseTestCase;
+import io.ebean.Ebean;
+import io.ebeantest.LoggedSql;
+
+/**
+ * Tests if outer joins are correctly used.
+ *
+ * @author Roland Praml, FOCONIS AG
+ *
+ */
+public class TestOuterJoin extends BaseTestCase {
+
+  @BeforeClass
+  public static void setup() {
+    ResetBasicData.reset();
+  }
+
+
+  @Test
+  public void testOuterOnNullQuery() throws Exception {
+
+    LoggedSql.start();
+    List<Customer> list = Ebean.find(Customer.class).where()
+        .isNull("orders")
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" where not exists "); // perfored with not exists query
+    assertThat(list).hasSize(2);
+
+    // use OR construct
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .or()
+          .isNull("orders.details.product.name")
+          .isNull("orders")
+        .endOr()
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" left join o_order ")
+      .contains(" left join o_order_detail ")
+      .contains(" left join o_product ")
+      .contains(" or not exists ");
+
+    assertThat(list).hasSize(4);
+
+    // use AND construct
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .and()
+          .isNull("orders.details.product.name")
+          .isNull("orders")
+        .endAnd()
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" left join o_order ")
+      .contains(" left join o_order_detail ")
+      .contains(" left join o_product ")
+      .contains(" and not exists ");
+
+    assertThat(list).hasSize(2);
+
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .isNull("orders.details.product.name")
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" left join o_order ")
+      .contains(" left join o_order_detail ")
+      .contains(" left join o_product ");
+    assertThat(list).hasSize(4);
+    LoggedSql.stop();
+  }
+
+  @Test
+  public void testInnerOnNonNullQuery() throws Exception {
+
+    LoggedSql.start();
+    List<Customer> list = Ebean.find(Customer.class).where()
+        .isNotNull("orders")
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" where exists "); // perfored with not exists query
+    assertThat(list).hasSize(2);
+
+    // use OR construct
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .or()
+          .isNotNull("orders.details.product.name")
+          .isNotNull("orders")
+        .endOr()
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" left join o_order ")
+      .contains(" left join o_order_detail ")
+      .contains(" left join o_product ")
+      .contains(" or exists ");
+
+    assertThat(list).hasSize(2);
+
+    // use AND construct
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .and()
+          .isNotNull("orders.details.product.name")
+          .isNotNull("orders")
+        .endAnd()
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+    .doesNotContain(" left join ")
+      .contains(" and exists ");
+
+    assertThat(list).hasSize(2);
+
+
+    LoggedSql.start();
+    list = Ebean.find(Customer.class).where()
+        .isNotNull("orders.details.product.name")
+        .le("id", 4) // ignore others than basicData
+        .findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .doesNotContain(" left join ");
+    assertThat(list).hasSize(2);
+    LoggedSql.stop();
+  }
+
+  @Test
+  public void testOuterOnFetch() throws Exception {
+    LoggedSql.start();
+
+    List<Order> orders1 =  Ebean.find(Order.class).findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" join o_customer") // ensure that we do not left join the customer
+      .doesNotContain(" left join o_customer");
+
+
+    // now fetch "details" bean, which may be optional
+    LoggedSql.start();
+
+    List<Order> orders2 =  Ebean.find(Order.class)
+        .fetch("details", "id").findList();
+
+    assertThat(LoggedSql.collect().get(0))
+      .contains(" left join o_order_detail ");
+
+    LoggedSql.stop();
+
+    // Note: You would expect, that the two lists are equal.
+    // but there is a @Where(clause = "${ta}.id > 0") on the details
+    // property, that will filter orders, where details is zero.
+
+    // The produced SQL is:
+    // select *  from o_order t0
+    //   join o_customer t2 on t2.id = t0.kcustomer_id
+    //   left join o_order_detail t1 on t1.order_id = t0.id
+    //   where t1.id > 0
+    //   order by t0.id, t1.id asc, t1.order_qty asc, t1.cretime desc; --bind()
+    //
+    // I think this is NOT correct as it may exclude orders without details or with negative ID
+    //
+    // Correct way could/would be, to add that extra where to the join
+    //
+    //
+
+    // assertThat(orders2).isEqualTo(orders1);
+  }
+
+}