6.0.2 fails to send to list of lists

[plowman]

Issue Summary

Something I ran into while upgrading to 6.0.2 just now is that when sending a Mail object with a to_emails= parameter that is a list of [[email, name]], a confusing exception is thrown while if it's a list of [(email, name)], it succeeds.

This snippet fails

from sendgrid import SendGridAPIClient
from sendgrid.helpers.mail import Mail

email_list = [["myemail+uno@gmail.com", "Benjamin Uno"],
              ["myemail+dos@gmail.com", "Benjamin Dos"]]
mail = Mail(subject=subject,
            html_content=content,
            from_email=("hello@website.com", "Website Team"),
            to_emails=email_list,
            )
sendgrid_client = SendGridAPIClient('abcd123')
sendgrid_client.send(mail)

The exception thrown is ValueError: Please use a To, Cc or Bcc object.

This snippet succeeds

email_list = [("myemail+uno@gmail.com", "Benjamin Uno"),
              ("myemail+dos@gmail.com", "Benjamin Dos")]

# (( Same code as above ))

Steps to Reproduce

1. Run the initial snippet above

Expected

• Option 1: accept a list of lists as well as a list of tuples. This seems doable but there may be ancient backwards incompatibility reasons why it's hard.
• Option 2: fail immediately if you see a list of lists. Otherwise the error "Please use a To, Cc or Bcc object." is pretty confusing and took me a while to figure out why sendgrid was unhappy.

Technical details:

• sendgrid-python Version: 6.0.2
• Python Version: 3.7

[thinkingserious]

Hi @plowman!

Thanks for reporting this! Yes, that error is confusing in this context and I'll leave this open for a fix.

to_emails currently requires either a list of Email/To/Cc/Bcc objects or a list of tuples. I did not think to include the ability of allowing a list of lists.

Would a better error do the trick or are you also wanting to be able to pass a list of lists?

With Best Regards,

Elmer

[plowman]

Hey @thinkingserious thanks for the fast reply! I don't have a strong preference on the fix. Throwing an error when I call send() with a list of lists would probably do the trick.

[helle253]

Is this still available? I have a couple of follow-up questions that are a bit beyond the scope of this issue, but may be worth taking a look at separately:

It looks like there may be some similar issues with parsing a list of dictionaries. Should this be fixed, too? Or is throwing a better error still an acceptable fix?

Similar parsing issues re:lists/dictionaries exist for adding BCC and CC parameters as well, but the Mail object doesn't take cc/bcc email parameters? What is the rationale for this?

Thanks :)