Updating Customer through rest/all/V1/customers/:id resets group_id if group_id not passed in payload

[abancroft0]

Preconditions

1. Magento Version 2.2.3 using rest API
2. Passing a JSON payload with minimum required data (email, first/last name, website_id, id)

Steps to reproduce

1. Update any customer who's group_id isn't the first group_id in the source list
2. Pass the customer payload with email, firstname, lastname, website_id, id

Expected result

1. I expect that only the data passed in the payload would be modified
2. Example: {"customer":{"email":"test@gmail.com","firstname":"magento","lastname":"user","website_id":1,"id":77486}} should leave the customer's full data structure unchanged.

Actual result

1. If the above customer had a group_id of 5, and our full group_id consisted of [1,2,3,4,5], the customer's group_id after passing the above payload would be set to 1:

Before:

PUT:

Results:

[bydrei]

@magento-engcom-team was able to replicate this. Ok if I self assign?

[magento-engcom-team]

Hi @ferrazzuk
Sure, feel free to assign it to yourself if you feel like trying and fixing this

Thanks!

[bydrei]

@magento-engcom-team pull request created.

[magento-engcom-team]

Hi @abancroft0. Thank you for your report.
The issue has been fixed in #14757 by @ferrazzuk in 2.1-develop branch
Related commit(s):

• 51f2f076a8fddbeb7b29914a1994236c29bdc369

The fix will be available with the upcoming 2.1.15 release.