You can use an add-on called Categories to Text which will save all an entry's categories into a channel field automatically.

• github: http://github.com/shoeshine/categories-to-text
• devot-ee: http://devot-ee.com/add-ons/categories-to-text (not published yet)

You can use an add-on called Categories to Text which will save all an entry's categories into a channel field automatically.

• github: http://github.com/shoeshine/categories-to-text
• devot-ee: http://devot-ee.com/add-ons/categories-to-text