#1331 - ENH: Support Aggregation formula with findSingleAttribute() ... max, min, avg, count and count(distinct ..)

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

@@ -273,13 +273,19 @@ class DefaultDbSqlContext implements DbSqlContext {
     sb.append(" ");
   }
 
+  @Override
+  public void appendParseSelect(String parseSelect) {
+    String converted = alias.parse(parseSelect);
+    sb.append(COMMA);
+    sb.append(converted);
+    appendColumnAlias();
+  }
+
   @Override
   public void appendFormulaSelect(String sqlFormulaSelect) {
 
     String tableAlias = tableAliasStack.peek();
-    String converted = StringHelper.replaceString(sqlFormulaSelect, tableAliasPlaceHolder,
-      tableAlias);
-
+    String converted = StringHelper.replaceString(sqlFormulaSelect, tableAliasPlaceHolder, tableAlias);
     sb.append(COMMA);
     sb.append(converted);
 

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

@@ -44,6 +44,13 @@ public class SqlBeanLoad {
     return lazyLoading;
   }
 
+  /**
+   * Return the DB read context.
+   */
+  public DbReadContext ctx() {
+    return ctx;
+  }
+
   /**
    * Increment the resultSet index 1.
    */
@@ -86,4 +93,14 @@ public class SqlBeanLoad {
     }
   }
 
+  /**
+   * Load the given value into the property.
+   */
+  public void load(BeanProperty target, Object dbVal) {
+    if (!refreshLoading) {
+      target.setValue(bean, dbVal);
+    } else {
+      target.setValueIntercept(bean, dbVal);
+    }
+  }
 }

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

@@ -418,7 +418,7 @@ public final class SqlTreeBuilder {
 
       // make sure we only included the base/embedded bean once
       if (!selectProps.containsProperty(baseName)) {
-        BeanProperty p = desc.findBeanProperty(baseName);
+        SqlTreeProperty p = desc.findSqlTreeProperty(baseName);
         if (p == null) {
           logger.error("property [" + propName + "] not found on " + desc + " for query - excluding it.");
 
@@ -436,7 +436,7 @@ public final class SqlTreeBuilder {
     } else {
       // find the property including searching the
       // sub class hierarchy if required
-      BeanProperty p = desc.findBeanProperty(propName);
+      SqlTreeProperty p = desc.findSqlTreeProperty(propName);
       if (p == null) {
         logger.error("property [" + propName + "] not found on " + desc + " for query - excluding it.");
         p = desc.findBeanProperty("id");

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

@@ -48,7 +48,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
    */
   private final boolean partialObject;
 
-  protected final BeanProperty[] properties;
+  protected final SqlTreeProperty[] properties;
 
   /**
    * Extra where clause added by Where annotation on associated many.
@@ -87,6 +87,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
   private boolean intersectionAsOfTableAlias;
 
   private final boolean aggregation;
+  private final boolean aggregationRoot;
 
   /**
    * Construct for leaf node.
@@ -124,13 +125,15 @@ class SqlTreeNodeBean implements SqlTreeNode {
     this.nodeBeanProp = beanProp;
     this.extraWhere = (beanProp == null) ? null : beanProp.getExtraWhere();
 
+    this.aggregation = props.isAggregation();
+    this.aggregationRoot = props.isAggregationRoot();
+
     // the bean has an Id property and we want to use it
-    this.readId = withId && (desc.getIdProperty() != null);
+    this.readId = !aggregationRoot && withId && (desc.getIdProperty() != null);
     this.disableLazyLoad = disableLazyLoad || !readId || desc.isRawSqlBased() || temporalVersions;
 
     this.partialObject = props.isPartialObject();
     this.properties = props.getProps();
-    this.aggregation = props.isAggregation();
     this.children = myChildren == null ? NO_CHILDREN : myChildren.toArray(new SqlTreeNode[myChildren.size()]);
 
     pathMap = createPathMap(prefix, desc);
@@ -186,7 +189,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
       }
       idBinder.buildRawSqlSelectChain(prefix, selectChain);
     }
-    for (BeanProperty property : properties) {
+    for (SqlTreeProperty property : properties) {
       property.buildRawSqlSelectChain(prefix, selectChain);
     }
     // recursively continue reading...
@@ -289,14 +292,14 @@ class SqlTreeNodeBean implements SqlTreeNode {
 
     if (inheritInfo == null) {
       // normal behavior with no inheritance
-      for (BeanProperty property : properties) {
+      for (SqlTreeProperty property : properties) {
         property.load(sqlBeanLoad);
       }
 
     } else {
       // take account of inheritance and due to subclassing approach
       // need to get a 'local' version of the property
-      for (BeanProperty property : properties) {
+      for (SqlTreeProperty property : properties) {
         // get a local version of the BeanProperty
         BeanProperty p = localDesc.getBeanProperty(property.getName());
         if (p != null) {
@@ -416,7 +419,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
     if (readId) {
       appendSelectId(ctx, idBinder.getBeanProperty());
     }
-    for (BeanProperty property : properties) {
+    for (SqlTreeProperty property : properties) {
       if (!property.isAggregation()) {
         property.appendSelect(ctx, subQuery);
       }
@@ -483,9 +486,9 @@ class SqlTreeNodeBean implements SqlTreeNode {
   /**
    * Append the properties to the buffer.
    */
-  private void appendSelect(DbSqlContext ctx, boolean subQuery, BeanProperty[] props) {
+  private void appendSelect(DbSqlContext ctx, boolean subQuery, SqlTreeProperty[] props) {
 
-    for (BeanProperty prop : props) {
+    for (SqlTreeProperty prop : props) {
       prop.appendSelect(ctx, subQuery);
     }
   }
@@ -543,7 +546,7 @@ class SqlTreeNodeBean implements SqlTreeNode {
     // join and return SqlJoinType to use for child joins
     joinType = appendFromBaseTable(ctx, joinType);
 
-    for (BeanProperty property : properties) {
+    for (SqlTreeProperty property : properties) {
       // usually nothing... except for 1-1 Exported
       property.appendFrom(ctx, joinType);
     }

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

@@ -1,7 +1,6 @@
 package io.ebeaninternal.server.query;
 
 import io.ebeaninternal.api.ManyWhereJoins;
-import io.ebeaninternal.server.deploy.BeanProperty;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -21,7 +20,7 @@ public class SqlTreeProperties {
   /**
    * The bean properties in order.
    */
-  private final List<BeanProperty> propsList = new ArrayList<>();
+  private final List<SqlTreeProperty> propsList = new ArrayList<>();
 
   /**
    * Maintain a list of property names to detect embedded bean additions.
@@ -32,6 +31,8 @@ public class SqlTreeProperties {
 
   private boolean aggregation;
 
+  private String aggregationPath;
+
   SqlTreeProperties() {
   }
 
@@ -39,17 +40,17 @@ public class SqlTreeProperties {
     return propNames.contains(propName);
   }
 
-  public void add(BeanProperty[] props) {
+  public void add(SqlTreeProperty[] props) {
     propsList.addAll(Arrays.asList(props));
   }
 
-  public void add(BeanProperty prop) {
+  public void add(SqlTreeProperty prop) {
     propsList.add(prop);
     propNames.add(prop.getName());
   }
 
-  public BeanProperty[] getProps() {
-    return propsList.toArray(new BeanProperty[propsList.size()]);
+  public SqlTreeProperty[] getProps() {
+    return propsList.toArray(new SqlTreeProperty[propsList.size()]);
   }
 
   boolean isPartialObject() {
@@ -77,7 +78,6 @@ public class SqlTreeProperties {
   boolean requireSqlDistinct(ManyWhereJoins manyWhereJoins) {
     String joinProperty = aggregationJoin();
     if (joinProperty != null) {
-      aggregation = true;
       manyWhereJoins.addAggregationJoin(joinProperty);
       return false;
     } else {
@@ -97,12 +97,21 @@ public class SqlTreeProperties {
    */
   private String aggregationJoin() {
     if (!allProperties) {
-      for (BeanProperty beanProperty : propsList) {
+      for (SqlTreeProperty beanProperty : propsList) {
         if (beanProperty.isAggregation()) {
-          return beanProperty.getElPrefix();
+          aggregation = true;
+          aggregationPath = beanProperty.getElPrefix();
+          return aggregationPath;
         }
       }
     }
     return null;
   }
+
+  /**
+   * Return true if a top level aggregation which means the Id property must be excluded.
+   */
+  public boolean isAggregationRoot() {
+    return aggregation && (aggregationPath == null);
+  }
 }

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

@@ -0,0 +1,76 @@
+package io.ebeaninternal.server.query;
+
+import io.ebeaninternal.server.deploy.DbReadContext;
+import io.ebeaninternal.server.deploy.DbSqlContext;
+import io.ebeaninternal.server.type.ScalarType;
+
+import java.util.List;
+
+/**
+ * A property in the SQL Tree.
+ *
+ * A BeanProperty or a dynamically created property based on formula.
+ */
+public interface SqlTreeProperty {
+
+  /**
+   * Return the property name.
+   */
+  String getName();
+
+  /**
+   * Return the full property name (for error messages).
+   */
+  String getFullBeanName();
+
+  /**
+   * Return true if the property is the Id.
+   */
+  boolean isId();
+
+  /**
+   * Return true if the property is an embedded type.
+   */
+  boolean isEmbedded();
+
+  /**
+   * Return true if the property is an aggregation.
+   */
+  boolean isAggregation();
+
+  /**
+   * Return the Expression language prefix (join path).
+   */
+  String getElPrefix();
+
+  /**
+   * Return the underlying scalar type for the property (for findSingleAttribute).
+   */
+  ScalarType<?> getScalarType();
+
+  /**
+   * For RawSql build the select chain.
+   */
+  void buildRawSqlSelectChain(String prefix, List<String> selectChain);
+
+  /**
+   * Load into the bean (from the DataReader/ResultSet).
+   */
+  void load(SqlBeanLoad sqlBeanLoad);
+
+  /**
+   * Ignore the property (moving the column index position without reading).
+   */
+  void loadIgnore(DbReadContext ctx);
+
+  /**
+   * Append to the select clause.
+   */
+  void appendSelect(DbSqlContext ctx, boolean subQuery);
+
+  /**
+   * Append to the from clause.
+   */
+  void appendFrom(DbSqlContext ctx, SqlJoinType joinType);
+
+}