Test if a tiddler with suffix exists

#1

Say, I have a tiddler $:/talha131/video/eg1. I want to test if $:/talha131/video/eg1/text exists.

Problem

  1. If $:/talha131/video/eg1 is present
  2. Then check if $:/talha131/video/eg1/text is present
  3. If $:/talha131/video/eg1/text is present then transclude its content

What have I tried?

I am working on a macro.

\define video(src, caption:"")

<$let url= {{{  [<__src__>is[tiddler]get[_canonical_uri]] }}}>
<$let subtitle= {{{  [<__src__>is[tiddler]get[video-subtitle]] }}}>

<$let url= {{{ [<__src__>is[tiddler]get[_canonical_uri]] }}}> works well to check if src is present. If it is, then it reads its _canonical_uri field.

But this syntax does not work, if I want to append a string to the tiddler title, <__src__>/text.

:x:

<$let video_text= {{{  [<__src__>/textis[tiddler]get[text]] }}}>

:x:

<$let video_text= {{{  [[<__src__>/text]is[tiddler]get[text]] }}}>

What’s the corect syntax to check if a tiddler exists inside a macro?

#2

@talha131 a tiddler exists as soon as it “has a title”, and contains content if it “has text”. So in filters we can say [[tiddlername]has[title]] or [[tiddlername]has[text]]. The has operator needs a value in the field tested.

  • If you want to can just ask to get the value [[tiddlername]get[text]] and if there is no text content, the filter does not return any value.
  • However there is the lookup operator as well. {{{ [[About]lookup[]] }}}
  • Using the above depending on how you use it you may need to wikify it

Your <$let url= {{{ [<__src__>is[tiddler]get[_canonical_uri]] }}}> can be simplified to <$let url= {{{ [<__src__>get[_canonical_uri]] }}}>

Rather than use the form<__src__> you can use $src$ eg; {{{ [[$src$]get[_canonical_uri]] }}} which also means you can use [[$src$/text]] but rememebr you also have the addsuffix[/text]] form.

  • Sometime we define a macro or set a variable if the text we wish to append clashes with the filer delimiters;
\define text-suffix() /text
\define video(src, caption:"")
... [<__src__>addsuffix<text-suffix>] ...
  • You can also use set/let/vars to define text-suffix

I have shown you the filter syntax how to

What’s the correct syntax to check if a tiddler exists inside a macro?

But what do you want to do with the result?

  • If it’s the text field perhaps just transclude the tiddler
    <$transclude tiddler={{{ [<__src__>addsuffix<text-suffix>] }}}/>

Regards
Tony

2 Likes
#3

The syntax issue in your code is with how to concatenate two strings into one.

<$let video_text= {{{ [<__src__>addsuffix[/text]is[tiddler]get[text]] }}}>

1 Like
#4

Thank you @TW_Tones and @saqimtiaz. With your help, this is the what I wrote

<$list filter="[<__src__>addsuffix[/text]is[tiddler]]">

<p>
    {{$src$/text||$:/talha131/Template/NavigateTranscludedTiddler}}
</p>

</$list>
#5

You can likely simplify as follows since inside the list widget the currentTiddler variable is being set to the tiddler you want to transclude:

<$list filter="[<__src__>addsuffix[/text]is[tiddler]]">

<p>
    {{||$:/talha131/Template/NavigateTranscludedTiddler}}
</p>

</$list>