html / template if range index子句

Question

I've got this template that parses multiple items of a slice onto the page. It does that really well.

However, I now want to use the very same template to parse a single value of the slice, based on the range index. The slice is used in multiple files so I can't just .Execute it like Slice[1:2]

{{ $bpi := .Index}}

{{ range $i, $elmt := .Slice }}
    {{ if $bpi.Equals $i }}
      <div>{{ .SliceContent }}</div>
    {{ end }}
{{ end }}

From what I've read is that the template isn't ment for computation, but if you've got a range index and if-statements in the html/template package it seems to me that I must be doing something wrong. I can write a FuncMap ofcourse, no problemo. But it doesn't seem right to me given these facts.

Answer 1

I am using something like this to conditionally include a default image or the first from a supplied slice of pictures. So I think this will provide you with the basis to do what you want. I check the slice has values, pulling the Nth item using the {{index .Slice n}} syntax as follows:

     {{ $idx := 2}}
     {{if .Pictures}}
       <img src="{{if .Pictures}}{{index .Pictures $idx}}{{end}}" alt="supplied first picture">
     {{else}}
       <img src="http://fpoimg.com/200x200?text=Placeholder(FPOimg.com)" alt="default picture">
     {{end}}

Therefore you can do the following:

    {{ $bpi := .Index}}

    {{ if .Slice }}
        {{ index .Slice $bpi }}
    {{ end }}