Determining that a Pandoc Variable is the Empty String

Determining that a Pandoc Variable is the Empty String

[S. Manning]

I would like to add a tag system to my static site which I generate with 
Pandoc templates.  Adding a tags: variable in myPage.yaml is easy, but 
then I want to add links from pages with the tag to the page for that 
tag.  Code like:

$for(tags)$
<a href="https://mysite.org/tags/$tags$.html">⇐ back to $tags$</a>&nbsp;
$endfor$

adds a link even if the tags variable is empty ("tags: " in the YAML 
file).

How can I check that the tag is not empty or a null string or however 
Pandoc defines it?

https://pandoc.org/MANUAL.html#interpolated-variables alludes to 
variable types such as string and list, but does not define them or 
explain how to get the attributes of complex variables such as lists.

-- 
You received this message because you are subscribed to the Google Groups "pandoc-discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To view this discussion on the web visit https://groups.google.com/d/msgid/pandoc-discuss/baea52e4f4b9a22d832faa30ab3fd116%40ageofdatini.info.

Re: Determining that a Pandoc Variable is the Empty String

[John MacFarlane]

Try

tags: []

in your YAML if you don't want the for loop to be executed.

> On Mar 7, 2023, at 8:41 PM, S. Manning <scriptor-aFO/2INALiozYggVrLCuDg@public.gmane.org> wrote:
> 
> I would like to add a tag system to my static site which I generate with Pandoc templates.  Adding a tags: variable in myPage.yaml is easy, but then I want to add links from pages with the tag to the page for that tag.  Code like:
> 
> $for(tags)$
> <a href="https://mysite.org/tags/$tags$.html">⇐ back to $tags$</a>&nbsp;
> $endfor$
> 
> adds a link even if the tags variable is empty ("tags: " in the YAML file).
> 
> How can I check that the tag is not empty or a null string or however Pandoc defines it?
> 
> https://pandoc.org/MANUAL.html#interpolated-variables alludes to variable types such as string and list, but does not define them or explain how to get the attributes of complex variables such as lists.
> 
> -- 
> You received this message because you are subscribed to the Google Groups "pandoc-discuss" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
> To view this discussion on the web visit https://groups.google.com/d/msgid/pandoc-discuss/baea52e4f4b9a22d832faa30ab3fd116%40ageofdatini.info.

-- 
You received this message because you are subscribed to the Google Groups "pandoc-discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To view this discussion on the web visit https://groups.google.com/d/msgid/pandoc-discuss/DA455835-3B72-4022-A761-E7A96E904EEA%40gmail.com.

Re: Determining that a Pandoc Variable is the Empty String

[S. Manning]

That works for me!  I will add it to my 'lab notes'

On 2023-03-07 21:44, John MacFarlane wrote:
> Try
> 
> tags: []
> 
> in your YAML if you don't want the for loop to be executed.
> 
>> On Mar 7, 2023, at 8:41 PM, S. Manning <scriptor-aFO/2INALiozYggVrLCuDg@public.gmane.org> 
>> wrote:
>> 
>> I would like to add a tag system to my static site which I generate 
>> with Pandoc templates.  Adding a tags: variable in myPage.yaml is 
>> easy, but then I want to add links from pages with the tag to the page 
>> for that tag.  Code like:
>> 
>> $for(tags)$
>> <a href="https://mysite.org/tags/$tags$.html">⇐ back to 
>> $tags$</a>&nbsp;
>> $endfor$
>> 
>> adds a link even if the tags variable is empty ("tags: " in the YAML 
>> file).
>> 
>> How can I check that the tag is not empty or a null string or however 
>> Pandoc defines it?
>> 
>> https://pandoc.org/MANUAL.html#interpolated-variables alludes to 
>> variable types such as string and list, but does not define them or 
>> explain how to get the attributes of complex variables such as lists.
>> 
>> --
>> You received this message because you are subscribed to the Google 
>> Groups "pandoc-discuss" group.
>> To unsubscribe from this group and stop receiving emails from it, send 
>> an email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
>> To view this discussion on the web visit 
>> https://groups.google.com/d/msgid/pandoc-discuss/baea52e4f4b9a22d832faa30ab3fd116%40ageofdatini.info.

-- 
You received this message because you are subscribed to the Google Groups "pandoc-discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email to pandoc-discuss+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org
To view this discussion on the web visit https://groups.google.com/d/msgid/pandoc-discuss/27db87ff42ad3fe1822144a366498919%40ageofdatini.info.