Developers can customise the behaviour of the plugin through filter hooks. There are many useful filter hooks supported by this plugin, and Gravity Forms has many filter hooks too.

1. gf_windcave_invoice_ref

   • string $invoice_ref
   • array $form
   • array $entry
   • return: string

   Change the invoice reference.

2. gf_windcave_invoice_trans_number

   • string $transaction_id
   • array $form
   • array $entry
   • return: string

   Change the the invoice transaction reference; NB: must be unique for the PxPay account!

3. gf_windcave_invoice_txndata1

   • string $data
   • array $form
   • array $entry
   • return: string

   Change the transaction custom data element 1.

4. gf_windcave_invoice_txndata2

   • string $data
   • array $form
   • array $entry
   • return: string

   Change the transaction custom data element 2.

5. gf_windcave_invoice_txndata3

   • string $data
   • array $form
   • array $entry
   • return: string

   Change the transaction custom data element 3.