Do not require all extra params in salesforce hook

[dstandish]

This is a small fixup for the salesforce hook.

Previously, code used extras["blah"] or None instead of simply extras.get("blah"), which forces users to add each of these optional params to the connection extra.

In this PR we use extras.get, which means user only needs to supply the extra param if necessary.

[eladkal]

see #18800

[josh-fell]

With how the custom connection fields currently work, there will always be a key for each of the custom fields in Extra. Since each one of these Salesforce connection params have their own custom field in the connection form, if a value is not provided it defaults to "". Users aren't required to enter a value for each extra param.

In the simple-salesforce package, the logic that determines what authentication type to use are all similar in format to:

if all(arg is not None for arg in (username, password, security_token)):
    ...

Unfortunately there is no authentication_type that is passed to explicitly state the authentication a user would like to integrate with.

Because the empty string is not None, there are chances that the incorrect authentication type is chosen which was the choice for the slightly clunky extras["extra__salesforce__<conn-field>"] or None approach.

[josh-fell]

All the authentication type logic in the Salesforce API starts here if you'd like to check it out.

[dstandish]

@josh-fell if you use secrets backend then what you say about custom connection fields does not apply, and when you upgrade to this provider, your connection no longer works

[josh-fell]

@josh-fell if you use secrets backend then what you say about customer connection fields does not apply, and when you upgrade to this provider, your connection no longer works

Ah I see. Valid point.

[dstandish]

I see so maybe we need to do get or None instead of slice or None?

[josh-fell]

I see so maybe we need to do get or None instead of slice or None?

Seems like the best approach.

[alexbegg]

I see so maybe we need to do get or None instead of slice or None?

@dstandish / @josh-fell
Doesn't get default to None? then why would this need a get or None?
Edit: Never mind, I just understood that if the key exists but it is an empty string, it should change to None in order to not break the built-in simple-salesforce authentication choosing method. Now I understand the need to get or None.

[alexbegg]

My PR is open that handles the defaulting to None issue (and also updates the tests to test it is handled correctly: #19530

[eladkal]

Closing as issue solved in #19530