Using variables in nested lists

[Diego Mesa]

Hey all,

I am trying to display a header for all posts tagged PoI that does, among other things, display any urls I've placed in its fields. For example, If I have a tiddler with the following fields:

paper-url: test1.com

hn-url: test2.com

blog-url: test3.com

I would like to have displayed

Paper: test1.com

HN: test2.com

Blog: test3.com

as the header. This is what I have so far:

<$list filter="[is[current]fields[]regexp[-url]]" variable="fieldname">

<$list filter="[[<<fieldname>>]split:before[-]]" variable="fieldprint">

<$text text=<<fieldprint>>/> : <$view  field=<<fieldname>>/> <br>

</$list>

</$list>

But this does not work. Without the split-before it renders as:

<<fieldname>> : test1.com 
<<fieldname>> : test2.com
<<fieldname>> : test3.com

which signifies that the <<fieldname>> isn't getting substituted correctly in the inner list. I tried adding a <$set> between the nesting, but that didn't work either. 

Any specific (and general!) help would be greatly appreciated!

Diego

[Diego Mesa]

After reading/searching/experimenting I got:

<$list filter="[is[current]fields[]regexp[-url]]" variable="fieldname">
<$list filter="[<fieldname>split:before[-]]" variable="fieldprint">
<$text text=<<fieldprint>>/>: <$view  field=<<fieldname>> /> <br/>

</$list>
</$list>

There is still some confusion about the use of << vs < when referencing variables, and why I don't have to wrap <fieldname> with [<fieldname>] before giving it to split. 

Remaining issues:

• actually making those render as URLs
• If I replace the <br/> with a comma to get them all on one line, I'm left with a trailing comma
• If I instead try to generate external links as:  [[<$text text=<<fieldprint>>/>|<$view field=<<fieldname>> />]]   it doesn't work. 

There is still some residual confusion about using nested lists as nested for loop analogs, and how to actually use the variables in the "loops".

[Xavier Cazin]

Hi Diego,

I think your second line should read:

<$list filter="[<fieldname>splitbefore[-]removesuffix[-]]" variable="fieldprint">

Best,

Xavier.

-- Xavier Cazin

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[Xavier Cazin]

Hi Diego,

I think the following butlast/last trick was given by Jed Carty a few hours ago. It looks quite verbose because the outer list is essentially duplicated, but I think it handles your three issues.

<$list filter="[is[current]fields[]regexp[-url]butlast[]]" variable="fieldname">
<$list filter="[<fieldname>splitbefore[-]removesuffix[-]]" variable="fieldprint">
<$text text=<<fieldprint>>/> : <$link to=<<fieldprint>>><$view  field=<<fieldname>>/></$link>,
</$list>
</$list>
<$list filter="[is[current]fields[]regexp[-url]last[]]" variable="fieldname">
<$list filter="[<fieldname>splitbefore[-]removesuffix[-]]" variable="fieldprint">
<$text text=<<fieldprint>>/> : <$link to=<<fieldprint>>><$view  field=<<fieldname>>/></$link>.
</$list>
</$list>

Best,

X.

-- Xavier Cazin

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[Diego Mesa]

Thanks Xavier! I was using tobias split:before, but I think that will also work.

Another update! I am almost there with:

<$list filter="[is[current]fields[]regexp[-url]]" variable="fieldname">
<$list filter="[<fieldname>

split:before[-]]" variable="fieldprint">
''<$text text=<<fieldprint>>/>'': <$transclude field=<<fieldname>> mode="inline"/>,
</$list>
</$list>

I still can't figure out how to not show the last comma. 

P.S. Sorry to keep spamming this with updates. You could see this as I prematurely posted and should have waited till I did more figure out, but: 1. The act of asking clarifies for me 2. Posting this thought process/evolution might be useful to others in the future! 

-- Xavier Cazin

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[Diego Mesa]

Thanks Xavier! I think that butlast and last will work! 

-- Xavier Cazin

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[Jed Carty]

For getting rid of the last comma, the same method I demonstrated here should work: https://groups.google.com/d/msg/tiddlywiki/D5CQvz_CpYw/0J0phbL4AwAJ

[Jed Carty]

Sorry, looking at that now it isn't obvious what I am talking about but it looks like you already have the same idea anyway using last and butlast.

[Diego Mesa]

Can some one clarify on the use of << vs < when referencing variables, and why I don't have to wrap <fieldname> with [<fieldname>] before giving it to split. 

Thanks!

[Eric Shulman]

On Saturday, December 2, 2017 at 7:29:05 PM UTC-8, Diego Mesa wrote:

Can some one clarify on the use of << vs < when referencing variables...

In TiddlyWiki *content*, variables are referenced using <<variableName>>.  The double-bracket syntax is used to avoid conflicts with standard HTML syntax (i.e., <b> starts normal HTML bold formatting, while <<b>> embeds the value of a TiddlyWiki variable named "b")

However, within TiddlyWiki *filters*, there is no need doubling the brackets, as HTML is not allowed *within* the filter, so only single <variableName> is used.

...and why I don't have to wrap <fieldname> with [<fieldname>] before giving it to split. 

Think of the brackets in filters as part of the operand itself rather than a "container" for the operand.  The type of bracket indicates the type of operand being used:

   use [...] for literal values, e.g., [texthere] 

   use {...} for field references, e.g., {!!fieldname}

   use <...> for variables e.g. <currentTiddler>

Thus, to split the literal text, "sometext", you could write:

   [title[sometext]splitbefore[t]removesuffix[t]]

you would get "some" as a result.

If the value "sometext" is stored in a field named "somefield" in the current tiddler, you could write:

  [{!!somefield}splitbefore[t]removesuffix[t]]

and, if the value "sometext" is stored in a variable named "somevariable", you could write:

  [<somevariable>splitbefore[t]removesuffix[t]]

As a slightly more complex example, suppose the value to split on was also stored in a variable.  Then you could write:

  [<somevariable>splitbefore<othervariable>removesuffix<othervariable>]

hope this helps,

enjoy,

-e

Eric Shulman

TiddlyTools.com: "Small Tools for Big Ideas!" (tm)

InsideTiddlyWiki: The Missing Manuals

[Diego Mesa]

Thanks for this explanation Eric! I've made a note in my wiki!