Changeset 28 for trunk/fmgVen/src/com/fmguler/ven/QueryGenerator.java

Timestamp:

Feb 9, 2011, 10:53:45 PM (14 years ago)

Author:

fmguler

Message:

Refs #3 - Ven.get() is converted to the new format. QueryGenerator and QueryMapper are mostly OK, generateRecursively and mapRecursively are converted and checked. Handles joins (includes/associations) many to one and one to many. For one to many, the reverse join field can be determined in a couple of ways. First way is (prefereed) having VenList as the list implementation which specifies the element class and the join field. Second way is using Java 1.5 generic type to detect element class (not yet implemented) and guessing join field by convention (if multiple joins exist, this won't work). The last way is to have some kind of annotation or configuration, which is of course the least preferred way. VenList has a static method to determine the element class in the object list, which currently calls getElementClass if the list is an instance of VenList. In the future other options can be implemented.

Getting object using joins (includes/associations) are tested using dummy assocations between SomeDomainObject and AnotherDomainObject. The Sample class builds the database, tests the operations and rolls back to the initial state. Database refactoring operations are moved to the LiquibaseUtil for clarity.

In the future, the generated queries will be shortened using hashed aliases, and the criteria subsystem will be implemented.

File:

• trunk/fmgVen/src/com/fmguler/ven/QueryGenerator.java (modified) (5 diffs)

trunk/fmgVen/src/com/fmguler/ven/QueryGenerator.java

@@ -19 +19 @@
 
 import com.fmguler.ven.util.Convert;
+import com.fmguler.ven.util.VenList;
 import java.beans.PropertyDescriptor;
 import java.util.Date;
 import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Set;
 import org.springframework.beans.BeanWrapper;
@@ -33 +36 @@
     private Set domainPackages;
     private Set dbClasses;
+    private boolean debug = true;
 
     public QueryGenerator() {
@@ -45 +49 @@
     }
 
-    public String generateSelectQuery() {
-        return null;
+    /**
+     * Generates select query for the specified object class and specified joins.
+     * @param joins set of joins that the query will contain
+     * @param objectClass the object class to select from
+     * @return the select SQL query
+     */
+    public String generateSelectQuery(Class objectClass, Set joins) {
+        long t1 = System.currentTimeMillis();
+        String objectName = Convert.toSimpleName(objectClass.getName());
+        String tableName = Convert.toDB(objectName);
+        StringBuffer selectClause = new StringBuffer("select ");
+        StringBuffer fromClause = new StringBuffer("from " + tableName);
+        generateRecursively(0, tableName, objectName, objectClass, joins, selectClause, fromClause);
+        selectClause.append(" 1=1");
+        if (debug) System.out.println("Ven - query generation time = " + (System.currentTimeMillis() - t1));
+        return selectClause.toString() + " \n" + fromClause.toString();
     }
 
@@ -129 +147 @@
      * @return the delete SQL query
      */
-    public String generateDeleteQuery(Class objectClass){
+    public String generateDeleteQuery(Class objectClass) {
         StringBuffer query = new StringBuffer();
         query.append("delete from ").append(Convert.toDB(Convert.toSimpleName(objectClass.getName()))).append(" where id = :id;");
         return query.toString();
     }
-        
+
     /**
      * Generates sequence query for the specified object
@@ -147 +165 @@
 
     //--------------------------------------------------------------------------
+    //PRIVATE METHODS
+    //recursively generate select query
+    private void generateRecursively(int level, String tableName, String objectPath, Class objectClass, Set joins, StringBuffer selectClause, StringBuffer fromClause) {
+        BeanWrapper wr = new BeanWrapperImpl(objectClass);
+        PropertyDescriptor[] pdArr = wr.getPropertyDescriptors();
+
+        for (int i = 0; i < pdArr.length; i++) {
+            Class fieldClass = pdArr[i].getPropertyType(); //field class
+            String fieldName = pdArr[i].getName(); //field name
+            Object fieldValue = wr.getPropertyValue(fieldName);
+            String columnName = Convert.toDB(pdArr[i].getName()); //column name
+
+            //direct database class (Integer, String, Date, etc)
+            if (dbClasses.contains(fieldClass)) {
+                selectClause.append(tableName).append(".").append(columnName).append(" as ").append(tableName).append("_").append(columnName); //column
+                selectClause.append(", ");
+            }
+
+            //many to one association (object property)
+            if (fieldClass.getPackage() != null && domainPackages.contains(fieldClass.getPackage().getName()) && joinsContain(joins, objectPath + "." + fieldName)) {
+                String joinTableAlias = tableName + "_" + columnName; //alias for table to join since there can be multiple joins to the same table
+                String joinTable = Convert.toDB(Convert.toSimpleName(fieldClass.getName())); //table to join
+                fromClause.append(" left join ").append(joinTable).append(" ").append(joinTableAlias);
+                fromClause.append(" on ").append(joinTableAlias).append(".id = ").append(tableName).append(".").append(columnName).append("_id");
+                generateRecursively(++level, joinTableAlias, objectPath + "." + fieldName, fieldClass, joins, selectClause, fromClause);
+            }
+
+            //one to many association (list property)
+            if (fieldValue instanceof List && joinsContain(joins, objectPath + "." + fieldName)) {
+                Class elementClass = VenList.findElementClass((List)fieldValue);
+                String joinTableAlias = tableName + "_" + columnName; //alias for table to join since there can be multiple joins to the same table
+                String joinTable = Convert.toDB(Convert.toSimpleName(elementClass.getName())); //table to join
+                String joinField = Convert.toDB(findJoinField((List)fieldValue)); //field to join
+                fromClause.append(" left join ").append(joinTable).append(" ").append(joinTableAlias);
+                fromClause.append(" on ").append(joinTableAlias).append(".").append(joinField).append("_id = ").append(tableName).append(".id");
+                generateRecursively(++level, joinTableAlias, objectPath + "." + fieldName, elementClass, joins, selectClause, fromClause);
+            }
+        }
+    }
+
+    //check if the joins contain the specified join
+    private boolean joinsContain(Set joins, String join) {
+        Iterator it = joins.iterator();
+        while (it.hasNext()) {
+            String str = (String)it.next();
+            if (str.startsWith(join)) {
+                if (str.length() == join.length()) return true;
+                else if (str.charAt(join.length()) == '.') return true;
+            }
+        }
+        return false;
+    }
+
+    //return the join field of the elements in the list
+    private String findJoinField(List list) {
+        if (list instanceof VenList) {
+            return ((VenList)list).getJoinField();
+        } else {
+            //find according to 1.5 generic or some convention (e.g. parent_obj_id)
+            return null;
+        }
+    }
+
+    //--------------------------------------------------------------------------
     //SETTERS
+    /**
+     * Add the domain packages that will be considered persistent
+     * @param domainPackage the domain package
+     */
     public void addDomainPackage(String domainPackage) {
         domainPackages.add(domainPackage);