Unexpected Mail instance categories, categories= behavior

[subvertallchris]

Issue Summary

SendGrid::Mail categories behavior makes it too easy to set empty values.

Steps to Reproduce

Instantiate a new instance

sg_mail = SendGrid::Mail.new

I know it will end up being an Arrary, so try to add something to it...

sg_mail.categories << 'foo'
# NoMethodError: undefined method `<<' for nil:NilClass

Oh, categories starts nil. I guess we need to instantiate it?

sg_mail.categories = []
sg_mail.categories
=> [nil]

An Array with nil in it. ???

More misleading is that if someone expects it to accept the String category, it will not complain, it will just add nil

sg_mail.categories = 'foo'
=> "foo"

sg_mail.categories
=> [nil, nil]

Despite its own awareness that it is an Array and its delegation of methods, it doesn't actually let me treat it like an array, so I don't have a clear way of fixing this.

sg_mail.categories.compact
=> []

sg_mail.categories
=> [nil, nil]

You could improve this by doing two things:

• New instances of Sendgrid::Mail should set categories to an empty Array. If nothing else, that would let callers know to treat it like an array and avoid categories= in the first place.

    def categories
      @categories ||= []
    end

https://github.com/sendgrid/sendgrid-ruby/blob/master/lib/sendgrid/helpers/mail/mail.rb#L908

• Fix categories=. I don't think that what you have defined works at all. When you call [string] on a String, you just select that pattern from the string. So if someone did do this:

# I guess this was what you had in mind?
sg_mail.categories = { categories: 'foo' }

# It would become this:
{ category: 'foo' }.to_json
=> "{\"category\":\"foo\"}"

# And then you're just pulling the word `category` out of it and storing it in your array
"{\"category\":\"foo\"}"['category']
=> "category"

This is also why calling categories= results in nil entries: it converts everything to a String with to_json and then whatever_your_string_is['categories'] always returns nil.

Technical details:

• sendgrid-ruby Version: 4.0.2
• Ruby Version: 2.2.3

[thinkingserious]

Excellent feedback @subvertallchris!

We would like to offer you some swag. Please email us at dx@sendgrid.com referencing this ticket with your mailing address and T-shirt size.

For this issue to rise up in our queue, we need +1s, comments or a pull request with a signed CLA.

Thanks!

[tkbky]

Related issue: #95

[thinkingserious]

Please follow progress on this issue here: #95

Thanks!