remove delete-orphan cascade from self referential mappers

diff --git a/doc/build/content/adv_datamapping.txt b/doc/build/content/adv_datamapping.txt
index e2f5f8ffb416a1bfc305234a5b1ee114fa9ad9d7..6ce0dd6dd2db9e5db2b08730ac407a47111d380f 100644 (file)
--- a/doc/build/content/adv_datamapping.txt
+++ b/doc/build/content/adv_datamapping.txt
@@ -622,7 +622,7 @@ Note that with a circular relationship as above, you cannot declare both relatio
 
 ### Self Referential Mappers {@name=recursive}
 
-A self-referential mapper is a mapper that is designed to operate with an <b>adjacency list</b> table.  This is a table that contains one or more foreign keys back to itself, and is usually used to create hierarchical tree structures.  SQLAlchemy's default model of saving items based on table dependencies is not sufficient in this case, as an adjacency list table introduces dependencies between individual rows.  Fortunately, SQLAlchemy will automatically detect a self-referential mapper and do the extra lifting to make it work.  
+A self-referential mapper is a mapper that is designed to operate with an *adjacency list* table.  This is a table that contains one or more foreign keys back to itself, and is usually used to create hierarchical tree structures.  SQLAlchemy's default model of saving items based on table dependencies is not sufficient in this case, as an adjacency list table introduces dependencies between individual rows.  Fortunately, SQLAlchemy will automatically detect a self-referential mapper and do the extra lifting to make it work.  
 
     {python}
     # define a self-referential table
@@ -642,7 +642,7 @@ A self-referential mapper is a mapper that is designed to operate with an <b>adj
     TreeNode.mapper = mapper(TreeNode, trees, properties={
             'children' : relation(
                             TreeNode, 
-                            cascade="all, delete-orphan"
+                            cascade="all"
                          ),
             }
         )
@@ -652,7 +652,7 @@ A self-referential mapper is a mapper that is designed to operate with an <b>adj
     
     mymapper.add_property('children', relation(
                             mymapper, 
-                            cascade="all, delete-orphan"
+                            cascade="all"
                          ))
         
 This kind of mapper goes through a lot of extra effort when saving and deleting items, to determine the correct dependency graph of nodes within the tree.
@@ -677,7 +677,8 @@ A self-referential mapper where there is more than one relationship on the table
             'children' : relation(
                             TreeNode, 
                             primaryjoin=trees.c.parent_node_id==trees.c.node_id
-                            cascade="all, delete-orphan"
+                            cascade="all",
+                            backref=backref("parent", foreignkey=trees.c.node_id)
                          ),
             'root' : relation(
                     TreeNode,