Sort broken for date

[julianbarg]

Describe the bug
I am trying to sort by a dictionary by a value that contains numbers. The sorting does not work, regardless of whether I use the value as-is or convert it to string.

Version of yq: 4.29.2
Operating system: linux
Installed via: snap

Input

- key: a
  date: 2011-09-12
- key: c
  date: 2011-10-05
- key: b
  date: 2010-12-09
- key: d
  date: 2011-10-20
- key: e
  date: 2010-09-29

I tried the following:

Command 1

yq '. | sort_by(.date)' ~/input.yaml

Output 1

- key: e
  date: 2010-09-29
- key: d
  date: 2011-10-20
- key: b
  date: 2010-12-09
- key: c
  date: 2011-10-05
- key: a
  date: 2011-09-12

Command 2

yq '[.[] | .date style="double"] | sort_by(.date)' input.yaml

Output 2

- key: e
  date: "2010-09-29"
- key: d
  date: "2011-10-20"
- key: b
  date: "2010-12-09"
- key: c
  date: "2011-10-05"
- key: a
  date: "2011-09-12"

Command 3

yq '[.[] | .date style="double"] |= sort_by(.date)' input.yaml

- key: a
  date: "2011-09-12"
- key: c
  date: "2011-10-05"
- key: b
  date: "2010-12-09"
- key: d
  date: "2011-10-20"
- key: e
  date: "2010-09-29"

Expected behavior

- key: e
  date: "2010-09-29"
- key: b
  date: "2010-12-09"
- key: a
  date: "2011-09-12"
- key: c
  date: "2011-10-05"
- key: d
  date: "2011-10-20"

Additional context
Looks like for some reason yq is reversing the order of the list. Except for the third command that is. I have no idea what is going on, but certainly is not expected behavior.

[mikefarah]

Yep that's a bug - I haven't added support for dates/timestamps in sort - will fix in next release!

[julianbarg]

Love to hear it. Note that the issue also occurs when converting the date to a string before sorting. That is a reliable workaround when using yymmdd because you effectively sort by number. Any idea why that is?

[mikefarah]

Yep, that transforms it to an integer, which will sort correctly 👍🏼

[julianbarg]

If you look at my command 2/3, when we just have integers in a string, it does not sort correctly also.

[mikefarah]

I can't replicate that :/

./yq '[.[] | .date style="double"] | sort_by(.date)' examples/data1.yaml 
- key: e
  date: "2010-09-29"
- key: b
  date: "2010-12-09"
- key: a
  date: "2011-09-12"
- key: c
  date: "2011-10-05"
- key: d
  date: "2011-10-20"

Note that the style parameter does not affect the value for sorting:

./yq 'sort_by(.date)' examples/data1.yaml  
- key: e
  date: "2010-09-29"
- key: b
  date: "2010-12-09"
- key: a
  date: "2011-09-12"
- key: c
  date: "2011-10-05"
- key: d
  date: "2011-10-20"

[julianbarg]

Good to know. May circle back on this if troubleshooting yields something relevant.

[julianbarg]

Just coming back to this to let you know that v4.30.4 has fixed the problem for me.