How Product Categories and Their Constraints Work

Source: product_categories_controller.rb:4-84

• Category name must be unique within a company (case-insensitive check via ILIKE) with a maximum of 30 characters
• A description is required for every category
• MYOB-integrated companies cannot set sales_tax_rate or purchase_tax_rate on product categories -- the system blocks the save with an error; the MYOB check also applies on update but only triggers if the tax rates have actually changed
• A category cannot be renamed if any product groups are assigned to it; however, the description can still be changed
• A category cannot be deleted if it has product groups -- remove or reassign all groups first
• Category list can include a "NONE" option (id = null, name = "NONE") when the include_none parameter is true
• Categories support integration-specific tax type fields for Xero and QuickBooks Online (xero_sales_tax_type, xero_purchase_tax_type, qbo_sales_tax_type, qbo_purchase_tax_type)

Support scenarios

• "Why can't I create a product category with this name?" → A category with the same name (case-insensitive) already exists
• "Why can't I set tax rates on my product category when I use MYOB?" → MYOB does not support category-level tax rates; the system blocks this
• "Why can't I rename this product category?" → The category has product groups assigned to it; change the description instead, or remove all groups first
• "Why can't I delete this product category?" → It still has product groups linked to it