How to modify the date parameter of a page?

support
1

Hi Hugo community

I’m working on a feature to support recurring events on a Hugo page. To do so, my approach is as follows: in the Front Matter, I add recurrence: (which can be set to weekly or monthly) and recurrence_end to define until when the recurrence has to be taken into account.

Then on the page I go through all events and add “new” events. My approach to add these “new” events is to copy the current event and then modify the dates accordingly.

{{ $events := .Pages }}
   {{ range sort $events ".Params.date" "asc" }}
      {{ if (and .Params.recurrence .Params.recurrence_end) }}
         {{ if eq .Params.recurrence "monthly" }}
            {{ $event := . }}
            {{ $date := $.Param "date" }}
            {{ $date := $date.AddDate 0 1 0 }} 
            {{ $event.date := $date }}
            {{ $events = $events | append $event }}
         {{ else if eq .Params.recurrence "weekly" }}
            {{/* {{ $events = $events | append . }} */}}
            {{ $event := . }}
            {{ $date := $.Param "date" }}
            {{ $date := $date.AddDate 0 0 7 }} 
            {{ $event.date := $date }}
            {{ $events = $events | append $event }}
      {{ end }}
   {{ end }}
{{ end }}

But Hugo complains about {{ $event.date := $date }} with unexpected ":=" in operand. My question is now, how can I modify the date (and other params in the Front Matter) of a copy of an event?

2

A Page is immutable. Yes, you made a copy of the Page but it is still a Page.

3

In this case, how can I get a mutable version of the Page?

4

Extract the values you need into a map or something.

5

Thanks for your hint @jmooring. Could you provide me an example? I’m not very used to Hugo’s way of variable handling.

6

This requires Hugo v0.95.0 or later.

git clone --single-branch -b hugo-forum-topic-37389 https://github.com/jmooring/hugo-testing hugo-forum-topic-37389
cd hugo-forum-topic-37389
hugo server

Be advised that the .AddDate method produces results that are “expected” by the Go team, but certainly not expected by me.

func main() {
	start := time.Date(2023, 01, 31, 0, 0, 0, 0, time.UTC)
	fmt.Printf("%v\n", start.AddDate(0, 1, 0))
}

2023-03-03 00:00:00 +0000 UTC

https://github.com/golang/go/issues/31145

Closing because this is working as documented and expected.

7

Thanks a lot @jmooring for the example. I did learn a lot from it. There is a last problem I’m facing.

Within {{ range sort $events "Date" }}{{ end }} (lines 47-52), I seem to have no access to .Page. E.g. {{with .Page.GetPage "/act/events"}}{{.Params.learn_more}}{{end}} doesn’t give me anything back.

8

That is correct, because you are ranging over a slice of maps, not over a page collection.

You need to add .Params.learn_more to each map as you range through the page collection.

I’ve update the repository. Pull changes and try it.

9

If you’re going to add more custom fields, it would make sense to include the .Page object when building the slice of maps.