#1837 (#1740 and #1744) - Inheritance on both sides of @ManyToOne

This change also relates back to #1740 and #1744 and changes the way that issue was fixed (by SqlTreeNodeBean on partially populated non-id inheritance bean).

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

@@ -21,9 +21,7 @@ class AssocOneHelpRefInherit extends AssocOneHelp {
   @Override
   void loadIgnore(DbReadContext ctx) {
     property.targetIdBinder.loadIgnore(ctx);
-    if (inherit.hasChildren()) {
-      ctx.getDataReader().incrementPos(1);
-    }
+    ctx.getDataReader().incrementPos(1);
   }
 
   /**
@@ -75,7 +73,7 @@ class AssocOneHelpRefInherit extends AssocOneHelp {
   @Override
   void appendSelect(DbSqlContext ctx, boolean subQuery) {
 
-    if (!subQuery && inherit.hasChildren()) {
+    if (!subQuery) {
       // add discriminator column
       String relativePrefix = ctx.getRelativePrefix(property.getName());
       String tableAlias = ctx.getTableAlias(relativePrefix);

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

@@ -10,7 +10,7 @@ public interface DbSqlContext {
   /**
    * Add a join to the sql query.
    */
-  void addJoin(String type, String table, TableJoinColumn[] cols, String a1, String a2, String inheritance);
+  void addJoin(String type, String table, TableJoinColumn[] cols, String a1, String a2);
 
   /**
    * Push the current table alias onto the stack.

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

@@ -219,9 +219,6 @@ public class InheritInfo {
    * Return the associated InheritInfo for this DB row read.
    */
   public InheritInfo readType(DbReadContext ctx) throws SQLException {
-    if (!hasChildren()) {
-      return this;
-    }
     return readType(ctx.getDataReader().getString());
   }
 

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

@@ -154,11 +154,8 @@ public final class TableJoin {
 
   public SqlJoinType addJoin(SqlJoinType joinType, String a1, String a2, DbSqlContext ctx) {
 
-    String inheritance = inheritInfo != null ? inheritInfo.getWhere() : null;
-
     String joinLiteral = joinType.getLiteral(type);
-    ctx.addJoin(joinLiteral, table, columns(), a1, a2, inheritance);
-
+    ctx.addJoin(joinLiteral, table, columns(), a1, a2);
     return joinType.autoToOuter(type);
   }
 

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

@@ -112,7 +112,7 @@ class DefaultDbSqlContext implements DbSqlContext {
   }
 
   @Override
-  public void addJoin(String type, String table, TableJoinColumn[] cols, String a1, String a2, String inheritance) {
+  public void addJoin(String type, String table, TableJoinColumn[] cols, String a1, String a2) {
 
     if (tableJoins == null) {
       tableJoins = new HashSet<>();
@@ -166,11 +166,6 @@ class DefaultDbSqlContext implements DbSqlContext {
       }
     }
 
-    // add on any inheritance where clause
-    if (inheritance != null && !inheritance.isEmpty()) {
-      sb.append(" and ").append(a2).append(".").append(inheritance);
-    }
-
     if (addAsOfOnClause) {
       sb.append(" and ").append(historySupport.getAsOfPredicate(a2));
     }

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

@@ -227,7 +227,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
 
     @Override
     void initBeanType() throws SQLException {
-      InheritInfo localInfo = inheritInfo.readType(ctx);
+      InheritInfo localInfo = readId ? inheritInfo.readType(ctx) : desc.getInheritInfo();
       if (localInfo == null) {
         // the bean must be null
         localIdBinder = idBinder;
@@ -539,7 +539,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
     }
 
     if (readId) {
-      if (!subQuery && inheritInfo != null && inheritInfo.hasChildren()) {
+      if (!subQuery && inheritInfo != null) {
         ctx.appendColumn(inheritInfo.getDiscriminatorColumn());
       }
       appendSelectId(ctx, idBinder.getBeanProperty());