reconcile config options with TinyTDS and documentation; coerce config values to expected types

[PaulCharlton]

reconcile config options with TinyTDS and documentation; coerce config values to expected types

extended discussion at: rails-sqlserver/tiny_tds#461
copied here =>

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TinyTDS v2.1.2 and current HEAD

Current State:

At the moment, the only "false" values for these configs are "nil" and the boolean value false, whereas all non-nil string values, including the empty string and the string "false" are interpreted as the boolean value true.

This presents several issues:

1. Rails developers left casting of config values to non-string types to each database adapter or their parent classes. see reference
   1.1. the config values :azure, :contained, and :use_utf16 are not well known to the scaffolding currently provided in rails, and are interpreted as string type.
2. Rails discards all non-string config values parsed from ENV 'DATABASE_URL', when merging into existing config, which means that there is no means for the environment variable to remove a config set in database.yml
   2.1 setting any of the aforementioned options in database.yml to any value other than nil can not be converted to a boolean false value by anything set in 'DATABASE_URL', even if 'DATABASE_URL' contains "?azure=false", it will be interpreted by TinyTDS as boolean true
3. meeting expectation of Rails developers.
   3.1 Rails ActiveRecord/ActiveModel has type conversions which already set expectations on how strings are converted to a target of boolean, ideally TinyTDS would use the same conversion.

Rails Reference and also Discussion here

Desired State:

1. all settings in DATABASE_URL, such as "?azure=false" should return "expected" config result of boolean false, consistent with ActiveRecord conversion from database native string to Ruby boolean.
2. [this one is Rails, not this Adapter]. a setting in DATABASE_URL such as "?azure=" should delete any existing config key named :azure [it used to work this way, need to research if it is a bug or a deliberate breaking change from past behavior]
3. unit tests for the above config settings which inject strings with falsy values instead of just booleans.

[PaulCharlton]

PR is forthcoming

[PaulCharlton]

see also: rails-sqlserver/tiny_tds#461 (comment)