ljharb/qs

Stringifying using different arrayFormats, then parsed, create different things

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#345 opened on Nov 15, 2019

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 (16 comments) (0 reactions) (0 assignees)JavaScript (8,015 stars) (744 forks)batch import
bughelp wantedparsequestionstringify

Description

It seems stringifying my metadata object with arrayFormat: brackets, then parsing it, creates a different object to stringifying with arrayFormat: indices then parsing that string.

> const qs = require('qs');

> metadata = [{key: "a", value: "2"}, {key: "b", value: "3"}]
[ { key: 'a', value: '2' }, { key: 'b', value: '3' } ]

> brackets = qs.stringify({"metadata": metadata}, { arrayFormat: "brackets"})
'metadata%5B%5D%5Bkey%5D=a&metadata%5B%5D%5Bvalue%5D=2&metadata%5B%5D%5Bkey%5D=b&metadata%5B%5D%5Bvalue%5D=3'

> parsed_brackets = qs.parse(brackets)
{ metadata: [ { key: [Array], value: [Array] } ] }

> parsed_brackets["metadata"]
[ { key: [ 'a', 'b' ], value: [ '2', '3' ] } ]

> indices = qs.stringify({"metadata": metadata}, { arrayFormat: "indices"})
'metadata%5B0%5D%5Bkey%5D=a&metadata%5B0%5D%5Bvalue%5D=2&metadata%5B1%5D%5Bkey%5D=b&metadata%5B1%5D%5Bvalue%5D=3'

> parsed_indices = qs.parse(indices)
{ metadata: [ { key: 'a', value: '2' }, { key: 'b', value: '3' } ] }

Am I doing something wrong? Is this expected? Is this just an issue with stringifying/parsing nested objects?

Contributor guide

Tech stack
javascript
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
understanding of qs array format options
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue demonstrates that stringifying with arrayFormat 'brackets' and then parsing yields a different structure than with 'indices'. Investigate the parsing logic in the library, likely in the `parse` function, to understand why the 'brackets' format results in an array with nested arrays for keys and values instead of an array of objects. Check if this is a known limitation or a bug that needs fixing. The fix may involve ensuring that the 'brackets' format round trips consistently.