Conditional 'isset' Suddenly No Longer Working

support
1

This is a weird one. One of those where some code which has been working perfectly in one site, refuses to work in another.

I’ve just duplicated a theme from one Hugo site to use as a starting point for another. There is some conditional template code to show tags [if they exist] as keywords in the header and as a clickable list at the bottom of each post. Heres what I have:

In frontmatter of post:

tags = ["oil", "pressure sensor", "leak", "switch"]

In /themes/mytheme/layouts/partials/header.html:

<meta name="keywords" content="{{ if isset .Params "tags" }}{{ range .Params.tags }}{{ . }}, {{ end }}{{end}}">

Works perfectly. Rendered HTML includes the tags:

<meta name="keywords" content="oil, pressure sensor, leak, switch, ">

Then, in /themes/mytheme/layouts/_default/single.html I have the following:

{{if isset .Params "tags" }}
    			<span class="footermetaheading">Meta</span>
    			TAGS:&#8196;{{ range .Params.tags }}<a class="tag" href="/tags/{{lower . }}">{{lower . }}</a>,&nbsp; {{ end }}<br/>
    			ORIGINAL PUBLICATION DATE:&#8196;{{.Date.Format "02 Jan 2006"}}<br/>
    			AUTHOR:&#8196;{{ .Site.Params.mdrauthor }}
    			{{ end }}
    			{{"<!--  end if it's a blog page show META //-->" | safeHTML}}
    			{{ end }}```

And nothing at all gets output. As I say, it's made all the more mysterious because the code is directly lifted from another of my site's themes, where it works perfectly.

Anything I might have missed here?

PS: In other [possibly] related news; in the aforementioned other site, some  other conditional code has suddenly stopped working as well:

I have set a ```mdrposticon``` variable in the frontmatter for my posts, where I select from a folder full of icon images for that post. If I don't specify a post icon, the template is supposed to fall back on the default icon. Here is the code:

Frontmatter: ```mdrposticon = ""``` [can be set or left blank]

And then in */themes/mytheme/layouts/_default/list.html* and */themes/mytheme/layouts/index.html* I have the following:

```<div class="posticon">
					{{ if isset .Params "mdrposticon" }}
					<img src="{{.Params.mdrposticon }}" />
					{{"<!--  Posticon. Otherwise show default //-->" | safeHTML}}
					{{ else }}
					<img src="/icons/default.png" />
					{{ end }}
				</div>```

Which was working last time I built the site. But now will not output anything, if I've not defined ````mdrposticon```` in the frontmatter.

I've not updated Hugo since last I built the site, so this is a complete mystery. But it seems strangely coincidental that two pieces of code relying on ``{{ isset }`` have started acting up. Can anyone think of anything else, however seemingly unrelated,  that might be borking this? 

Hugo doesn't throw up any errors, on building the sites.
2

Well, would you believe it!

After tearing my hair out for two days over this and then posting a long-winded plea for help on here, I’ve just spotted the problem [Ain’t it always the way!]

Looking at the whole block of conditional code I pasted in above for adding tags to the bottom of individual posts [instead of just the bit that writes the tags] I spotted the following:

    			{{ if eq .Params.mdrpagetype "blogpage" }}
    			{{"<!--  if it's a blog page show META //-->" | safeHTML}}
    			{{if isset .Params "tags" }}
    			<span class="footermetaheading">Meta</span>
    			TAGS:&#8196;{{ range .Params.tags }}<a class="tag" href="/tags/{{lower . }}">{{lower . }}</a>,&nbsp; {{ end }}<br/>
    			ORIGINAL PUBLICATION DATE:&#8196;{{.Date.Format "02 Jan 2006"}}<br/>
    			AUTHOR:&#8196;{{ .Site.Params.mdrauthor }}
    			{{ end }}
    			{{"<!--  end if it's a blog page show META //-->" | safeHTML}}
    			{{ end }}
    		</footer>```

Note the ```{{ if eq .Params.mdrpagetype "blogpage" }}``` line.

So, what had happened was that when I started importing my new site into Hugo and referring to my existing one as a template, I had looked at my existing site and saw that each post was defined as such by having in the frontmatter: ```mdrpagetype="blogpage"```.

In the nanosecond it took me to switch project windows from old site to new site, this had become scrambled in my brain to ```mdrpagetype="blogpost"``` which I had duly added into the frontmatter for all the posts in the new site.  Result: although Hugo was reading the tags fine all the time, the entire block they were nested in was being ignored because the page types had been set wrong.

So a classic case of the error lying between chair and keyboard!

Now, while I'm on a roll, should I try and suss out the missing post icons, or just go and lie down in a dark corner for a bit?