Ability to reject deeply nested blank attributes

[ignat-z]

Allow passing :nested_all_blank as argument for accepts_nested_attributes_for to reject fully blank attributes by recursion traversing of all hashes in attributes.

Can be used to filter blank attributes if model depends more than one level of nesting.
Related to #19490

Using recursive traverse instead of stack because of:

Calculating -------------------------------------
           recursion     5.320k i/100ms
               stack     3.905k i/100ms
-------------------------------------------------
           recursion     58.193k (± 3.7%) i/s -    292.600k
               stack     40.710k (± 3.3%) i/s -    206.965k

Comparison:
           recursion:    58193.3 i/s
               stack:    40710.1 i/s - 1.43x slower

Calculating -------------------------------------
recursion with value     8.036k i/100ms
    stack with value     4.658k i/100ms
-------------------------------------------------
recursion with value     87.259k (± 3.8%) i/s -    441.980k
    stack with value     48.642k (± 3.5%) i/s -    246.874k

Comparison:
recursion with value:    87259.5 i/s
    stack with value:    48642.5 i/s - 1.79x slower

source

[sgrif]

Thank you for the feature proposal, but I do not think there is a compelling enough use case for this change in the framework itself. Perhaps you could make this a gem, and see if there's interest.

[siakaramalegos]

👍

[ignat-z]

If somebody meets the same problem
https://github.com/ignat-zakrevsky/reject_deeply_nested

[danielricecodes]

@sgrif - IMHO the Rails framework should offer support for rejecting deeply nested attributes. It is a framework feature to accept_nested_attributes_for in the first place. Shouldn't the Rails framework feature work when you stack accept_nested_attributes_for declarations and your ActiveRecord models are related using Rails associations like has_many, has_one, or belongs_to?

Seems pretty simple to do really since all that this would required is a slight tweak to this proc

To illustrate what a deeply nested blank Param's hash looks like, here is an example of one. Rails really should consider this not blank???

{"first_name"=>"",
 "middle_name"=>"",
 "last_name"=>"",
 "suffix"=>"",
 "home_address_attributes"=>{"street1"=>"", "street2"=>"", "county"=>"", "city"=>"", "state"=>"", "zipcode"=>""},
 "mailing_address_attributes"=>{"street1"=>"", "street2"=>"", "county"=>"", "city"=>"", "state"=>"", "zipcode"=>""},
 "home_phone_number"=>"",
 "mobile_phone_number"=>"",
 "email_address"=>"",
 "at_address_years"=>"",
 "at_address_months"=>"",
 "monthly_mortgage"=>"",
 "home_ownership"=>"",
 "date_of_birth"=>"",
 "ssn"=>"",
 "drivers_license_id_number"=>"",
 "drivers_license_state"=>"",
 "drivers_licence_expires_at"=>"",
 "employer_name"=>"",
 "employment_address_attributes"=>{"city"=>"", "state"=>""},
 "time_at_employer_years"=>"",
 "time_at_employer_months"=>"",
 "job_title"=>"",
 "employment_status"=>"",
 "employer_phone_number"=>"",
 "gross_monthly_income"=>"",
 "other_monthly_income"=>""}