How to Process Braintree Payment with existing customerId

Question

Trying to set up iOS and PHP payment system using Braintree.

I can set up a clientToken with

$clientToken["client_token"] = Braintree_ClientToken::generate());
return ($clientToken);

And I can process a first payment with:

$result = Braintree_Transaction::sale(array(
        'amount' => '1',
        'paymentMethodNonce' => $nonce,
        'customer' => array(
            'id' => 'testId',
            'firstName' => 'John',
            'lastName' => 'Doe',
            'email' => 'john@doe.com',
        ),
        'options' => array(
            'submitForSettlement' => true,
            'storeInVaultOnSuccess' => true,
        )
      ));

However when I try to process a second payment I get the error:

91609 – Customer ID has already been taken.

How can I process a second payment for the same customer with the same customerId ('testId') - why does it throw an error when I try to pass the payment with an existing customer ID? Surely it should just attach the payment to that same customer? Isn't that what it's there for?

Edit: So after looking around a bit more I found another field I can include in the Braintree_Transaction::sale as follows:

'customerId' => 'testId',

So this will allow me to re-use a customerId stored in the Braintree vault. However for a first time transaction I get the error:

91510 – Customer ID is invalid.

So I end up in a catch 22 - I can use the first set of code for a new customer but not repeat customers and I can use the second for repeat customers but not new. I cannot use both together. So my solution is to create my own local database entry that determines whether a user has paid via braintree before or not and substitute the code accorrdingly. Is there a more streamlined approach?

Answer 1

_{I work at Braintree. If you need more help, you can always reach out to our support team.}

You've got the right idea. You need track on your side whether a customer ID exists with Braintree.

There is an alternative, but I don't recommend it, as it takes an extra API call.

You can first try to create the customer with Braintree, ignoring an error if the error code is 91510:

$result = Braintree_Customer::create(array(
        'id' => 'testId',
        'firstName' => 'John',
        'lastName' => 'Doe',
        'email' => 'john@doe.com',
));

Then, you know that either the customer already existed, or you just created it, and you can use your second method to create a transaction.