Hugo template to create complex table. Has `caption`, `tfoot`, and `colgroup` HTML feature.

content.md

{{< create-table src="my-table" >}}

create-table.html

<!-- Collect all params and initialize variables -->
{{ $data := .Site.Data }}
{{ $src := .Get "src" }}
{{ $pathComponents := split $src "/" }}

<!-- Iterate through the .Site.Data since it is actually a dict -->
{{ range $component := $pathComponents }}
    {{ if ne $data nil }}
        {{ $data = index $data $component }}
    {{ end }}
{{ end }}

<!--
    Function to create <col /><col /><col />...
    Make sure to only receive Slice
-->
{{ define "create-col" }}
    {{ $items := . }}

    {{ if not (reflect.IsSlice $items )}}
        {{ errorf "Invalid `col` format." }}
    {{ end }}

    {{ range $col := $items }}
        <col {{ range $attr, $value := $col }} {{$attr}}="{{$value}}" {{ end }} />
    {{ end }}
{{ end }}

<!-- 
    Function to create <th>a</th><th>b</th><th>c</th>... 
    Make sure to only receive Slice
-->
{{ define "create-th" }}
    {{ $items := . }}

    {{ if not (reflect.IsSlice $items )}}
        {{ errorf "Invalid `th` format." }}
    {{ end }}

    {{ range $value := $items }}
        <th>{{ $value }}</th>
    {{ end }}
{{ end }}

<!-- 
    Function to create <td>a</td><td>b</td><td>c</td>... 
    Make sure to only receive Slice
-->
{{ define "create-td" }}
    {{ $items := . }}

    {{ if not (reflect.IsSlice $items )}}
        {{ errorf "Invalid `td` format." }}
    {{ end }}

    {{ range $value := $items }}
        <td>{{ $value }}</td>
    {{ end }}
{{ end }}

<!-- 
    Process `head` element, breakdown map of slice into slice
-->
{{ define "process-head" }}
    {{ $rows := . }}
    {{ range $key, $value := $rows }}
        {{ if and (not (reflect.IsMap $value)) (not (reflect.IsSlice $value)) }}
            {{ errorf "Invalid `head` format." }}
        {{ end }}

        {{ if reflect.IsSlice $value }}
            <tr>{{ template "create-th" $value }}</tr>
        {{ else if reflect.IsMap $value }}
            {{ template "process-head" $value }}
        {{ end }}
    {{ end }}
{{ end }}

<!-- 
    Process `body` element, breakdown map of slice into slice
-->
{{ define "process-body" }}
    {{ $rows := . }}
    {{ range $key, $value := $rows }}
        {{ if and (not (reflect.IsMap $value)) (not (reflect.IsSlice $value)) }}
            {{ errorf "Invalid `body` format." }}
        {{ end }}

        {{ if reflect.IsSlice $value }}
            <tr>{{ template "create-td" $value }}</tr>
        {{ else if reflect.IsMap $value }}
            {{ template "process-body" $value }}
        {{ end }}
    {{ end }}
{{ end }}

<!-- 
    Process `foot` element, breakdown map of slice into slice
-->
{{ define "process-foot" }}
    {{ $rows := . }}
    {{ range $key, $value := $rows }}
        {{ if and (not (reflect.IsMap $value)) (not (reflect.IsSlice $value)) }}
            {{ errorf "Invalid `foot` format." }}
        {{ end }}

        {{ if reflect.IsSlice $value }}
            <tr>{{ template "create-th" $value }}</tr>
        {{ else if reflect.IsMap $value }}
            {{ template "process-foot" $value }}
        {{ end }}
    {{ end }}
{{ end }}

<!--
    Function to build table, populate mandatory element of table first
    and then render later
-->
{{ define "build-table" }}
    {{ $table := . }}
    {{ $caption := "" }}
    {{ $head := slice }}
    {{ $body := slice }}
    {{ $foot := slice }}
    {{ $colGroup := slice }}

    {{ range $key, $value := $table }}
        {{ if eq $key "head" }}
            {{ $head = $head | append $value }}
        {{ else if eq $key "body" }}
            {{ $body = $body | append $value }}
        {{ else if eq $key "foot" }}
            {{ $foot = $foot | append $value }}
        {{ else if eq $key "colgroup" }}
            {{ if not (reflect.IsSlice $value) }}
                {{ errorf "Invalid `colgroup` format. Must be an array." }}
            {{ end }}
            {{ $colGroup = $value }}
        {{ else if eq $key "caption" }}
            {{ if gt (len $value) 0 }}
                {{ if eq (printf "%T" $value) "string" }}
                    {{ $caption = $value }}
                {{ else }}
                    {{ errorf "`caption` must be plain string." }}
                {{ end }}
            {{ end }}
        {{ else }}
            {{ errorf "Undefined table format. Key: %q" $key }}
        {{ end }}
    {{ end }}

    {{ if gt (len $caption) 0 }}
        <caption>{{ $caption }}</caption>
    {{ end }}

    {{ if gt (len $colGroup) 0 }}
        <colgroup>{{ template "create-col" $colGroup }}</colgroup>
    {{ end }}

    {{ if gt (len $head) 0 }}
        <thead>{{ template "process-head" $head }}</thead>
    {{ end }}
    
    {{ if gt (len $body) 0 }}
        <tbody>{{ template "process-body" $body }}</tbody>
    {{ end }}
    
    {{ if gt (len $foot) 0 }}
        <tfoot>{{ template "process-foot" $foot }}</tfoot>
    {{ end }}
{{ end }}

<table>
    {{- template "build-table" $data -}}
</table>

my-table.toml

caption = "Table Caption"

[[head]]
  row = ["Table Heading 1", "Table Heading 2", "Table Heading 3", "Table Heading 4", "Table Heading 5"]

[[body]]
  row = ["Table Cell 1", "Table Cell 2", "Table Cell 3", "Table Cell 4", "Table Cell 5"]
  row2 = ["Table Cell 1", "Table Cell 2", "Table Cell 3", "Table Cell 4", "Table Cell 5"]

[[body]]
  row = ["Table Cell 1", "Table Cell 2", "Table Cell 3", "Table Cell 4", "Table Cell 5"]

[[body]]
  row = ["Table Cell 1", "Table Cell 2", "Table Cell 3", "Table Cell 4", "Table Cell 5"]

[[foot]]
  row = ["Table Footer 1", "Table Footer 2", "Table Footer 3", "Table Footer 4", "Table Footer 5"]

# [[colgroup]]
#   span = 1
#   class = "first-group"

# [[colgroup]]
#   span = 2
#   class = "second-group"

# [[colgroup]]
#   span = 2
#   class = "third-group"