#1740 and #1744 Don't include the discriminator column on Inheritance query on a type that has no sub-types

Fix for #1740

src/main/java/io/ebeaninternal/server/deploy/AssocOneHelpRefInherit.java

@@ -74,7 +74,7 @@ class AssocOneHelpRefInherit extends AssocOneHelp {
   @Override
   void appendSelect(DbSqlContext ctx, boolean subQuery) {
 
-    if (!subQuery) {
+    if (!subQuery && inherit.hasChildren()) {
       // add discriminator column
       String relativePrefix = ctx.getRelativePrefix(property.getName());
       String tableAlias = ctx.getTableAlias(relativePrefix);

src/main/java/io/ebeaninternal/server/deploy/InheritInfo.java

@@ -6,8 +6,8 @@ import io.ebeaninternal.server.deploy.id.IdBinder;
 import io.ebeaninternal.server.deploy.parse.DeployInheritInfo;
 import io.ebeaninternal.server.query.SqlTreeProperties;
 
-import java.lang.reflect.Modifier;
 import javax.persistence.PersistenceException;
+import java.lang.reflect.Modifier;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -175,6 +175,16 @@ public class InheritInfo {
     return children;
   }
 
+  /**
+   * Return true if this node has children.
+   * <p>
+   * When an inheritance node has no children then we don't need
+   * the discriminator column as the type is effectively known.
+   */
+  public boolean hasChildren() {
+    return !children.isEmpty();
+  }
+
   /**
    * Get the bean property additionally looking in the sub types.
    */
@@ -200,7 +210,6 @@ public class InheritInfo {
 
     for (InheritInfo childInfo : children) {
       selectProps.add(childInfo.descriptor.propertiesLocal());
-
       childInfo.addChildrenProperties(selectProps);
     }
   }
@@ -209,9 +218,10 @@ public class InheritInfo {
    * Return the associated InheritInfo for this DB row read.
    */
   public InheritInfo readType(DbReadContext ctx) throws SQLException {
-
-    String discValue = ctx.getDataReader().getString();
-    return readType(discValue);
+    if (!hasChildren()) {
+      return this;
+    }
+    return readType(ctx.getDataReader().getString());
   }
 
   /**
@@ -327,7 +337,6 @@ public class InheritInfo {
    * Return the derived where for the discriminator.
    */
   public String getWhere() {
-
     return where;
   }
 

src/main/java/io/ebeaninternal/server/deploy/parse/DeployInheritInfo.java

@@ -199,9 +199,7 @@ public class DeployInheritInfo {
   public String getWhere() {
 
     List<Object> discList = new ArrayList<>();
-
     appendDiscriminator(discList);
-
     return buildWhereLiteral(discList);
   }
 

src/main/java/io/ebeaninternal/server/query/SqlTreeNodeBean.java

@@ -543,10 +543,9 @@ class SqlTreeNodeBean implements SqlTreeNode {
     }
 
     if (readId) {
-      if (!subQuery && inheritInfo != null) {
+      if (!subQuery && inheritInfo != null && inheritInfo.hasChildren()) {
         ctx.appendColumn(inheritInfo.getDiscriminatorColumn());
       }
-
       appendSelectId(ctx, idBinder.getBeanProperty());
     }
     appendSelect(ctx, subQuery, properties);

src/test/java/org/tests/aggregateformula/IAFBaseSegment.java

@@ -0,0 +1,18 @@
+package org.tests.aggregateformula;
+
+import javax.persistence.DiscriminatorColumn;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Inheritance;
+import javax.persistence.Table;
+
+@Entity
+@Inheritance
+@Table(name = "iaf_segment")
+@DiscriminatorColumn(name = "ptype")
+public class IAFBaseSegment {
+
+  @Id
+  private Long id;
+
+}

src/test/java/org/tests/aggregateformula/IAFPartialSegment.java

@@ -0,0 +1,30 @@
+package org.tests.aggregateformula;
+
+import javax.persistence.DiscriminatorValue;
+import javax.persistence.Entity;
+import javax.persistence.Inheritance;
+import javax.persistence.ManyToOne;
+
+@Entity
+@Inheritance
+@DiscriminatorValue("target")
+public class IAFPartialSegment extends IAFBaseSegment {
+
+  private final long segmentIdZat;
+
+  @ManyToOne(optional = false)
+  private final IAFSegmentStatus status;
+
+  public IAFPartialSegment(long segmentIdZat, IAFSegmentStatus status) {
+    this.segmentIdZat = segmentIdZat;
+    this.status = status;
+  }
+
+  public long getSegmentIdZat() {
+    return segmentIdZat;
+  }
+
+  public IAFSegmentStatus getStatus() {
+    return status;
+  }
+}

src/test/java/org/tests/aggregateformula/IAFSegmentStatus.java

@@ -0,0 +1,35 @@
+package org.tests.aggregateformula;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "iaf_segment_status")
+public class IAFSegmentStatus {
+
+  @Id
+  private long id;
+
+  private String name;
+
+  public IAFSegmentStatus(String name) {
+    this.name = name;
+  }
+
+  public long getId() {
+    return id;
+  }
+
+  public void setId(long id) {
+    this.id = id;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+}

src/test/java/org/tests/aggregateformula/TestAggregateInheritFormula.java

@@ -0,0 +1,39 @@
+package org.tests.aggregateformula;
+
+import io.ebean.DB;
+import org.ebeantest.LoggedSqlCollector;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class TestAggregateInheritFormula {
+
+  @Test
+  public void test() {
+
+    IAFSegmentStatus st0 = new IAFSegmentStatus("st0");
+    IAFSegmentStatus st1 = new IAFSegmentStatus("st1");
+
+    IAFPartialSegment p0 = new IAFPartialSegment(108, st0);
+    IAFPartialSegment p1 = new IAFPartialSegment(108, st1);
+    IAFPartialSegment p2 = new IAFPartialSegment(109, st0);
+
+    DB.saveAll(Arrays.asList(st0, st1, p0, p1));
+
+    LoggedSqlCollector.start();
+
+    List<IAFPartialSegment> segments =
+      DB.find(IAFPartialSegment.class)
+        .select("segmentIdZat, min(status)")
+        .where().eq("segmentIdZat", 108L)
+        .findList();
+
+    final List<String> sql = LoggedSqlCollector.stop();
+
+    assertThat(segments).hasSize(1);
+    assertThat(sql.get(0)).contains("select t0.segment_id_zat, min(t0.status_id) from iaf_segment t0 where t0.ptype = 'target'  and t0.segment_id_zat = ? group by t0.segment_id_zat");
+  }
+}

src/test/java/org/tests/query/other/TestQuerySingleAttribute.java

@@ -23,7 +23,6 @@ import static org.assertj.core.api.Assertions.assertThat;
 
 public class TestQuerySingleAttribute extends BaseTestCase {
 
-
   @Test
   public void exampleUsage() {
 
@@ -236,8 +235,7 @@ public class TestQuerySingleAttribute extends BaseTestCase {
       .select("more");
 
     query.findSingleAttributeList();
-    assertThat(sqlOf(query)).contains("select distinct t0.more from rawinherit_parent t0 where t0.type = 'A' ");
-
+    assertThat(sqlOf(query)).contains("select distinct t0.more from rawinherit_parent t0 where t0.type = 'A'");
   }
 
   @Test