tpl: intersect needs some love

[moorereason]

The following test cases fail when added to tpl/template_funcs_test.go:TestIntersect:

{[]string{"a", "b", "c"}, []string{"a", "b", "b"}, []string{"a", "b"}},
{[]interface{}{"a", "b", "c"}, []interface{}{"a", "b", "b"}, []interface{}{"a", "b"}},

Test results:

--- FAIL: TestIntersect (0.00s)
        template_funcs_test.go:791: [0] got [a b b] but expected [a b]
        template_funcs_test.go:791: [1] got [] but expected [a b]

Regarding test 0, in is used by intersect to avoid adding duplicates to the new set. In this case, in is receiving a reflect.Value struct, but the reflect.Struct case is not handled by in.

Regarding test 1, intersect does not handle the reflect.Interface case. See Questions about "intersect" function forum discussion.

Tests were done in Go 1.6 and Hugo HEAD.

[robertbasic]

@moorereason @bep is this issue addressed? (I'm looking for things to contribute to, so just want to avoid working on already fixed stuff).

[moorereason]

@robertbasic,
The first test above is resolved (#1972).

I have a fix for the second test. It's in one of my personal branches (8e81d2e). However, there's still a piece missing, which this test will hit:

{[]string{"a", "b", "c"}, []interface{}{"a", "b", "b"}, []string{"a", "b"}},

If you want to take my branch as a starting point and finish it out, go for it! I probably won't have time to finish it for a few days.

[bep]

This issue has been automatically marked as stale because it has not been commented on for at least four months.

The resources of the Hugo team are limited, and so we are asking for your help.

If this is a bug and you can still reproduce this error on the master branch, please reply with all of the information you have about it in order to keep the issue open.

If this is a feature request, and you feel that it is still valuable, please open a proposal at https://discuss.gohugo.io/.

This issue will automatically be closed in four months if no further activity occurs. Thank you for all your contributions.

[bep]

Note/Update: This issue is marked as stale, and I may have said something earlier about "opening a thread on the discussion forum". Please don't.

If this is a bug and you can still reproduce this error on the latest release or the master branch, please reply with all of the information you have about it in order to keep the issue open.

If this is a feature request, and you feel that it is still relevant and valuable, please tell us why.

[jacksingleton]

I think I've ran into this issue.

When trying to implement related content functionality I thought I'd be able to write:

{{ $has_common_context := intersect .Params.contexts ($.Scratch.Get "context") }}

However, this yields [] even when the slices share common elements.

upon closer inspection ({{ printf "%#v" ... }}) I see that:

.Params.contexts = []string{"blah"}

while

$.Scratch.Get "context" = []interface {}{"blah"}

Anyone know of a work around?

[jacksingleton]

For the record, I suspect this was happening because I was populating "context" in Scratch using slice (in order to normalize situations where only one context exists).

I worked around it by giving up on normalizing a single value into an array of one value, instead branching into a conditional and using in or intersect depending on whether it's a single value or an array:

{{ if $.Scratch.Get "context" }}
  {{ $.Scratch.Set "has_common_context" (in .Params.contexts ($.Scratch.Get "context")) }}
{{ else }}
  {{ $.Scratch.Set "has_common_context" (intersect .Params.contexts ($.Scratch.Get "contexts")) }}
{{ end }}
{{ $has_common_context := ($.Scratch.Get "has_common_context") }}

Note: "contexts" instead of "context" in the else branch.

Ugly, but it works.

[samozzy]

I'm experiencing this issue, but intersect seems entirely broken. The following happens:

  {{ $a := (slice 1 2 3 ) }}
  {{ $b := (slice 1 3 4 ) }}
  {{ $c := intersect $a $b }}
  a: {{ $a }} {{ printf "%#v" $a }} //Result: [1 2 3] []interface {}{1, 2, 3}
  b: {{ $b }} {{ printf "%#v" $b }} //Result:[1 3 4] []interface {}{1, 3, 4}
  c: {{ $c }} {{ printf "%#v" $c }} //Result: [] []interface {}{}

Expected behaviour: $c is [1 3]

Any ideas?

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.