@dan I figured out how to pass a fixed amount through the "additional messages" with on_sent_ok, but I'm not sure how to make that amount come from user input.
Maybe this could work for you if you have a fixed amount you want to pass over to check out at PayPal. Here's what I did:
1. Make a button on PayPal. In my case I didn't save it, just generated the code for the button and pasted that into a text file. I find that it's easier to customize when I don't save the button on PayPal. So that means there isn't a
2. Then in the Contact 7 Additional Settings I pasted my url with the variables. I'm also using the sandbox version of PayPal. If you haven't tried the Sandbox, you should definitely check it out. It allows you to do all kinds of testing as if you're using the Live PayPal site.
on_sent_ok: "location = 'https://firstname.lastname@example.org&cmd=_xclick&amount=50';"
You can see the last variable I'm passing is the
amount=50. You can probably pass any of the allowed HTML Variables for a button type in there too.
I used the LIVE HTTP Headers Extension in Firefox to examine a regular PayPal transaction that I already have working on my staging site. Super helpful.
And if anyone knows how I can pass an amount into my params I'd really appreciate it!