Index: openacs-4/packages/dotlrn-ecommerce/lib/section.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/dotlrn-ecommerce/lib/section.tcl,v
diff -u -r1.8 -r1.9
--- openacs-4/packages/dotlrn-ecommerce/lib/section.tcl	6 Jul 2005 17:05:50 -0000	1.8
+++ openacs-4/packages/dotlrn-ecommerce/lib/section.tcl	7 Jul 2005 18:17:23 -0000	1.9
@@ -137,13 +137,30 @@
 	from dotlrn_ecommerce_section
 	where section_id = :section_id
     }
+
+    set tree_options [list]
+    db_foreach prerequisites {
+	select tree_id
+	from dotlrn_ecommerce_prereq_map
+    } {
+	lappend tree_options [list [category_tree::get_name $tree_id] $tree_id]
+    }
+
     ad_form -extend -name add_section -form {
 	{categories:text(category),multiple,optional
 	    {label "Categories"}
 	    {html {size 4}}
 	    {value "$community_id $package_id"}
 	}
     }
+
+    if { [llength $tree_options] > 0 } {
+	ad_form -extend -name add_section -form {
+	    {prerequisites:integer(checkbox),multiple,optional {label "Check Prerequisites"}
+		{options {$tree_options}}
+	    }
+	}
+    }
 } else {
     ad_form -extend -name add_section -form {
 	{categories:text(category),multiple,optional
@@ -194,6 +211,15 @@
 						     [list "${field_identifier}:text(radio),optional" {label $field_name} {value $default_value} {options {{Yes t} {No f}}}] \
 						    ]
     }
+
+    # maxparticipants is a special field, it is created on install
+    # it can be empty but not zero or negative
+    if { $field_identifier == "maxparticipants" } {
+	lappend validate {maxparticipants
+	    { $maxparticipants > 0 || [empty_string_p $maxparticipants] }
+	    "Please enter a value greater than 0"
+	}
+    }
 }
 
 # Create the section for predefined sessions
@@ -203,8 +229,6 @@
     set sessions_list [list]
 }
 
-ns_log Notice "** $sessions_list **"
-
 if { [llength $sessions_list] } {
     ad_form -extend -name add_section -form {
 	{-section "Predefined Sessions"}
@@ -327,6 +351,12 @@
 	    set member_price [template::util::currency::create "$" [lindex $member_price_split 0] [lindex $member_price_split 1] ]
 	}
     }
+
+    set prerequisites [db_list prerequisites {
+	select tree_id
+	from dotlrn_ecommerce_prereqs
+	where section_id = :section_id
+    }]
 } -new_data {
     db_transaction {
         # create the class instance
@@ -463,6 +493,17 @@
 	set tree_id [parameter::get -package_id [ad_conn package_id] -parameter PatronRelationshipCategoryTree -default 0]
 	category_tree::map -tree_id $tree_id -object_id $community_id
 
+	# Prerequisites
+	if { [info exists prerequisites] } {
+	    foreach prereq $prerequisites {
+		db_dml insert_prereq {
+		    insert into dotlrn_ecommerce_prereqs
+		    (section_id, tree_id)
+		    values
+		    (:section_id, :prereq)
+		}
+	    }
+	}
     }
 
     # HAM : let's now add a "Section Administration" portlet for this new section
@@ -644,6 +685,22 @@
 	    }
 	}
 	
+	# Prerequisites
+	if { [info exists prerequisites] } {
+	    db_dml delete_prereq {
+		delete from dotlrn_ecommerce_prereqs
+		where section_id = :section_id
+	    }
+	    foreach prereq $prerequisites {
+		db_dml insert_prereq {
+		    insert into dotlrn_ecommerce_prereqs
+		    (section_id, tree_id)
+		    values
+		    (:section_id, :prereq)
+		}
+	    }
+	}
+
 	dotlrn_ecommerce::section::flush_cache $section_id
     }
 } -after_submit {
Index: openacs-4/packages/dotlrn-ecommerce/lib/tree-chunk.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/dotlrn-ecommerce/lib/tree-chunk.tcl,v
diff -u -r1.8 -r1.9
--- openacs-4/packages/dotlrn-ecommerce/lib/tree-chunk.tcl	7 Jul 2005 00:35:32 -0000	1.8
+++ openacs-4/packages/dotlrn-ecommerce/lib/tree-chunk.tcl	7 Jul 2005 18:17:23 -0000	1.9
@@ -363,7 +363,7 @@
     if { [parameter::get -package_id [ad_conn package_id] -parameter NoPayment -default 0] } {
 	set shopping_cart_add_url [export_vars -base register/ { community_id product_id}]
     } else {
-    	set shopping_cart_add_url [export_vars -base ecommerce/shopping-cart-add { user_id product_id }]
+	set shopping_cart_add_url [export_vars -base ecommerce/prerequisite-confirm { user_id product_id return_url }]
     }
 
     set member_p [dotlrn_community::member_p $community_id $user_id]
@@ -448,4 +448,4 @@
 		set prices ""
 	}
     }
-}
\ No newline at end of file
+}
Index: openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-create.sql
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-create.sql,v
diff -u -r1.8 -r1.9
--- openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-create.sql	23 Jun 2005 12:31:21 -0000	1.8
+++ openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-create.sql	7 Jul 2005 18:17:22 -0000	1.9
@@ -65,10 +65,22 @@
 	internal_account text
 );
 
+-- user_field should point to person_info fields
+-- maybe the person_info fields should be object attributes
+create table dotlrn_ecommerce_prereq_map (
+	tree_id		integer references category_trees on delete cascade not null,
+	user_field	text
+);
+
+create table dotlrn_ecommerce_prereqs (
+	section_id	integer references dotlrn_ecommerce_section on delete cascade not null,
+	tree_id		integer references category_trees on delete cascade not null
+);
+
 -- Create custom ecommerce field
 insert into ec_custom_product_fields (field_identifier, field_name, default_value, column_type, last_modified,last_modifying_user, modified_ip_address) values ('maxparticipants', 'Max Participants', '', 'integer', now(), '0', '0.0.0.0');
 alter table ec_custom_product_field_values add maxparticipants integer;
 alter table ec_custom_p_field_values_audit add maxparticipants integer;
 
 \i dotlrn-ecommerce-memberships-create.sql
-\i dotlrn-ecommerce-admin-portlet-create.sql
\ No newline at end of file
+\i dotlrn-ecommerce-admin-portlet-create.sql
Index: openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-drop.sql
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-drop.sql,v
diff -u -r1.5 -r1.6
--- openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-drop.sql	19 Jun 2005 06:05:06 -0000	1.5
+++ openacs-4/packages/dotlrn-ecommerce/sql/postgresql/dotlrn-ecommerce-drop.sql	7 Jul 2005 18:17:22 -0000	1.6
@@ -7,8 +7,11 @@
 -- @cvs-id $Id$
 --
 
+drop table dotlrn_ecommerce_transactions;
+drop table dotlrn_ecommerce_prereqs;
+drop table dotlrn_ecommerce_prereq_map;
 drop table dotlrn_ecommerce_section;
 drop table person_info;
 
 select acs_rel_type__drop_role('as_session_role');
-select acs_rel_type__drop_role('ec_product_role');
\ No newline at end of file
+select acs_rel_type__drop_role('ec_product_role');
Index: openacs-4/packages/dotlrn-ecommerce/www/admin/process-purchase-course.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/dotlrn-ecommerce/www/admin/process-purchase-course.tcl,v
diff -u -r1.10 -r1.11
--- openacs-4/packages/dotlrn-ecommerce/www/admin/process-purchase-course.tcl	6 Jul 2005 16:51:08 -0000	1.10
+++ openacs-4/packages/dotlrn-ecommerce/www/admin/process-purchase-course.tcl	7 Jul 2005 18:17:22 -0000	1.11
@@ -325,9 +325,11 @@
 	    {help_text "How is the purchaser related to the participant?"}
 	    {options {$tree_options}}
 	}
+	{isubmit:text(submit) {label "Continue"}}
 	{-section "Group Purchase"}
 	{name:text,optional {label "Group Name"} {html {size 30}}}
 	{num_members:integer(text),optional {label "Number of attendees"} {html {size 30}}}
+	{gsubmit:text(submit) {label "Continue"}}
     }
 
     lappend validate {name
@@ -413,7 +415,7 @@
 #    if { ! $waiting_list_p } {
 	lappend validate \
 	    {num_members
-		{ $num_members > 1 }
+		{ $num_members > 1 || [template::element::get_value participant related_user] != -1 }
 		"[_ dotlrn-ecommerce.lt_Please_enter_a_value_]"
 	    } {num_members
 		{ $num_members <= $available_slots || [empty_string_p $num_members] || [template::element::get_value participant related_user] != -1}
@@ -501,11 +503,11 @@
 	set participant_id $group_id
 	set item_count $num_members
 
-	ad_returnredirect [export_vars -base "../ecommerce/shopping-cart-add" { product_id user_id participant_id item_count }]
+	ad_returnredirect [export_vars -base "../ecommerce/prerequisite-confirm" { product_id user_id participant_id item_count return_url }]
 	ad_script_abort
     }
     
-    set add_url [export_vars -base "../ecommerce/shopping-cart-add" { product_id user_id participant_id item_count }]
+    set add_url [export_vars -base "../ecommerce/prerequisite-confirm" { product_id user_id participant_id item_count return_url }]
     set participant_id [ad_decode $participant_id 0 $user_id $participant_id]
 
     if { $new_user_p } {