[Improvement] (merge function) Multiple merging dict

[ngdangtu-vn]

My current hugo version:

• Hugo Static Site Generator: v0.74.3-DA0437B4 linux/arm
• BuildDate: 2020-07-23T16:22:34Z

The current merge function only allow merge a pair of dict. However, in a certain case, more than two dicts could be merged. For example, if you want to make JSON template, dict is the best option for clean code. But if an object with too many properties could lead to a huge trouble.

{{- $obj := newScratch -}}
{{- $obj.Add "list" slice -}}
{{ $paginator := .Paginate (where .Site.RegularPages "Type" .Site.Data.Sections.Home.main) }}
{{- range $paginator.Pages -}}
	{{- $obj.Add "list" (dict "title" .Title "url" .Permalink "author" .Params.author "desc" .Description "pubdate" (dict "short" (.PublishDate.Format .Site.Params.DateFormats.Short) "long" (.Date.Format "2006-01-02T15:04:05") )) -}}
{{- end -}}
{{- $obj.Get "list" | jsonify -}}

Instead of that, merge is recommend to break down an infinitive long line for the sake of clean code.

{{- $obj := newScratch -}}
{{- $obj.Add "list" slice -}}
{{ $paginator := .Paginate (where .Site.RegularPages "Type" .Site.Data.Sections.Home.main) }}
{{- range $paginator.Pages -}}
	{{- $sDate := dict "short" (.PublishDate.Format .Site.Params.DateFormats.Short) -}}
	{{- $lDate := dict "long" (.Date.Format "2006-01-02T15:04:05") -}}
	{{- $pubdate := dict "pubdate" (merge $sDate $lDate) -}}

	{{- $require := dict "title" .Title "url" .Permalink -}}
	{{- $optional := dict "author" .Params.author "desc" .Description -}}

	{{- $obj.Add "list" (merge $require $optional $pubdate) -}}
{{- end -}}
{{- $obj.Get "list" | jsonify -}}

But with the merge limited, the above code is impossible to achieve.

Error: Error building site: failed to render pages: render of "home" failed: "/bla/bla/bla/layouts/index.json:12:22": execute of template failed: template: index.json:12:22: executing "index.json" at <merge>: wrong number of args for merge: want 2 got 3

I think it would be nice if we could have this improvement for the next update.

[ngdangtu-vn]

Right now, I'm trying to get around with .SetInMap:

{{- $obj := newScratch -}}
{{- $obj.Add "list" slice -}}
{{ $paginator := .Paginate (where .Site.RegularPages "Type" .Site.Data.Sections.Home.main) }}
{{- range $paginator.Pages -}}
	{{- $obj.SetInMap "item" "title" .Title -}}
	{{- $obj.SetInMap "item" "url" .Permalink -}}
	{{- $obj.SetInMap "item" "author" .Params.author -}}
	{{- $obj.SetInMap "item" "desc" .Description -}}

	{{- $sDate := dict "short" (.PublishDate.Format .Site.Params.DateFormats.Short) -}}
	{{- $lDate := dict "long" (.Date.Format "2006-01-02T15:04:05") -}}
	{{- $obj.SetInMap "item" "pubdate" (merge $sDate $lDate) -}}

	{{- $obj.Add "list" ($obj.Get "item") -}}
	{{- $obj.Delete "item" -}}
{{- end -}}
{{- $obj.Get "list" | jsonify -}}

But for more complex json, merge function still seems to work better.

[bep]

I haven't read this is in detail, but wouldn't this be somehow the same: {{ $m = $m | merge $m2 | merge $m3 }} ....?

[ngdangtu-vn]

Is it even possible to make a chain for merge? I didn't know about this.

Update:
Yeah, pipeline merge seems to work fine. But do you think this {{ $m = merge $m $m2 $m3 }} is better? It seems shorter to me :D

[bep]

It seems shorter to me :D

And potentially more effective, I agree.

[moorereason]

I've submitted a PR for consideration.

[github-actions]

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