In a field, append to an existing list - with correct brackets

#1

In a tiddler I have myfield: foo [[bar bar]]

Via my myprocedure(appendthis) I want to set a tiddler field so its value concatenates its old value with the argument, to get the field value foo [[bar bar]] [[just appended]] (or possibly [[foo]] [[bar bar]] [[just appended]]). Order doesn’t matter.

But it is surprisingly difficult to get the brackets right. I get everything from no brackets to quadruples to… well, you get it. I’ve tried format:titlelist[] but nope.

What to do?

\procedure myprocedure(appendthis)
<$button>go
<$action-setfield
	$tiddler=<<currentTiddler>>
	myfield= ...
/>
</$button>
\end
<<myprocedure "just appended">>

Thank you!

#2

Hi Mat

Try this (barely tested):

\procedure myprocedure(appendthis)
<$button>go
<$action-setfield
	$tiddler=<<currentTiddler>>
	myfield={{{ [<appendthis>format:titlelist[]] [{!!myfield}] +[join[ ]] }}}
/>
</$button>
\end
<<myprocedure "just appended">>


;myfield
:<$codeblock code={{!!myfield}}/>

Hope this helps,

Fred

#3

Try this:

<$action-listops $tags=<<currentTiddler>> />

#4

Oh, yeah! Thank you so much!

(reflection: That is certainly too… I don’t know the appropriate word… maybe “special” or “intricate”… I’m a pretty darn experiened TW user and I get trapped in bits like these too often, so I am pretty sure it affects others too… Is it a docs matter? Are we missing operators? Is there a more fundamental problem on the side of TW or myself?.. hmm…)

#5

Hm, I didn’t try it yet, but how can that possibly concatenate anything?

#6

See https://tiddlywiki.com/#ActionListopsWidget

#7

In your example, code would be:
<$action-listops $field="myfield" $subfilter="[<appendthis>]" />

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#8

<$action-listops $field="myfield" $subfilter="[<appendthis>]" />

I was just about to post this after some experimentation!

Thank you @tw-FRed and @saqimtiaz

1 Like
#9

Both versions (action-listops and action-setfield) have the same limit: procedure parameter is considered as a single value to be appended to the existing list field.

If the parameter actually contains a list, not a single value, and the purpose is to merge this list with current field content, then it doesn’t work as is.

#10

This. Code that edits lists can be tricky if you want to support spaces in the list items. A more complete documentation reading list, to help you understand what’s available for this kind of thing:

  • action-listops widget
  • enlist filter operator
  • set widget
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#11 
<$let mylist="[[Tiddler A]] [[Tiddler B]] C">
<$button>go<$action-listops $field="myfield" $subfilter=<<mylist>> /></$button>
</$let>
3 Likes