Single-valued attributes are stored as empty strings after form submission

[little9]

Descriptive summary

When a work has single-valued attributes and the form is submitted, empty strings are stored.

Rationale

Having these values change after form submission means that views and other code that exports them has to check for nil and an empty string. It would cleaner for the values to remain nil unless they aren't an empty string.

Expected behavior

The value of the single-valued attribute is nil until it becomes a non-empty string.

Actual behavior

The value of blank single-valued attribute become "" after submitted the work form.

Steps to reproduce the behavior

1. Create a work that has a single-valued attribute
2. Submit a form for the work
3. Check the attribute:

work.single_value
""

or view the show page:

Related work

curationexperts/epigaea#331
curationexperts/epigaea#618

[jcoyne]

See #2297 (comment)

[dchandekstark]

The code referenced by @jcoyne does not clean single-valued fields in the desired way -- i.e., cleaning '' to nil.

irb(main):008:0> foo = ''
=> ""
irb(main):009:0> foo.delete('')
=> ""
irb(main):010:0> foo
=> ""

[dchandekstark]

The fix for https://github.com/samvera/hydra-editor/blob/master/app/forms/hydra_editor/form.rb#L60-L62 could be something like:

terms.each do |key|
  if multiple?(key)
    clean_params[key].delete('') # also compact?
  elsif clean_params[key] == ''
    clean_params[key] = nil
  end
end

[no-reply]

This will be fixed upon support of hydra-editor 4.0.0.

@jrgriffiniii are there blockers to a 4.0.0 release?