implement table with parent child relationship

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http://www.symfony-project.org/forum/index.php?t=msg&goto=11511#msg_11511

I was looking for the best way to implement a parent child relationship in a single table. I use this to allow for unlimited sub-categories in an ecommerce application.

Here is the method I included in my Category.php class for the parent_id field.

mclarke4

implement table with parent child relationship

I've always been a fan of using a Modified Preorder Tree Traversal for complex parent/Child tree structures. Someone even made a plugin to simplify this with propel.

http://www.symfony-project.org/trac/wiki/HowToHandleHierarchicalDataWithPropel

documented on: 05 September 2006, Draven

implement table with parent child relationship

I have also created a helper script to populate a select list with categories with the child categories indented underneath.

eg.

PHP
-- Symfony
-- Smarty
-- Eclipse PHP
Linux
-- Distros
-- Fedora
-- Ubuntu
-- Kernel

I use these mainly on the admin section for adding products to categories etc. You have to override the default template created for the module that needs this helper. Basically copy the relevant file from cache and change object_select_tag to object_select_tag_parent_child.

The code relies on the getTopLevel mehtod defined above being implmented.