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Change the treatment of falsy values in _.toQuery and _.fromQuery?

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
javascript
Domain
web-dev

Research direction

Start with the _.toQuery and _.fromQuery entry points and review the linked pull-request discussion. Decide how null, undefined, empty strings, and numeric zero should round-trip, including whether jQuery conventions apply. Done means an agreed behavior is documented and both functions have coverage for the selected cases.

Written by the indexing model from the issue text.

Description

after modules question

@yashshah1 pointed out a problem with _.toQuery and _.fromQuery: through stringification, falsy values are being "upgraded" to truthy if you encode them and then decode them again. For example, _.fromQuery(_.toQuery({a: null})) returns {a: 'null'}.

@yashshah1 proposed the following solution in https://github.com/documentcloud/underscore-contrib/pull/229#issuecomment-683548408:

What I am suggesting is a change in both toQuery and fromQuery.

Proposed behaviour:

_.toQuery('{ a: '', b: null, c: undefined, d: '10' }')
// a=&b=&d=10

_.fromQuery('a=&b=&d=10')
// { a: '', b: '', d: '10' }

Reasoning
The idea is that toQuery and fromQuery need to be as complementary to each other as possible, one drawback that's seen already is that numbers need to be re-parsed. Wrt falsy values, however, I think there has to be a special provision as described above.

What we gain by this is that null values are re-encoded as empty strings, which is falsy, and undefined isn't included in the object, which leads to almost the same usage in a few cases.

var obj = { a: '', b: null, c: undefined, d: '10' }
console.log(obj['c']) // undefined

obj = _.fromQuery(_.toQuery(obj))
console.log(obj['c']) // undefined

This might lead to a change in the behaviour of fromQuery and I am happy to raise a PR should this be acceptable.

I'm not sure whether this approach would be the right solution, for a couple of reasons:

  • Information loss: undefined, null and the empty string '' could no longer be distinguished.
  • What to do with numeric zero?
  • How does this align with jQuery's encoding conventions?

However, this is something we can discuss. Let's do that here.

Dominant language
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