How to build an external href from values in fields

#1

HI, very new to TW5 andI just can’t get the syntax right for this. I’m trying to make the href part of an external link from values in the fields of a tiddler. I feel like this should work:

The tiddler has two fields defined:
lat:123.12
lon:-30.23

Tiddler text is:

<a href="http://mydomain.com?lat={{!!lat}}&lon={{!!lon}}">test</a>

I would expect the produced link would be

http://mydomain.com?lat=123.12&lon=-30.23

but the link that is built is:

domain.com/?{{!!lat}}&{{!!lon}}

No transclusion seems to be happening?

What is the right incantation for this?

Thanks so much. TW5 looks amazing but I’m still trying to get my head around it.

#2

Widget and HTML parameter values (e.g., the href value in <a href=...>) are not “wikified”, so the embedded transclusions are left as-is.

However, you can use “filtered transclusion” to construct the entire href parameter value, like this:

<a href={{{ [[http:/mydomain.com?lat=]] [{!!lat}] [[&lon=]] [{!!lon}] +[join[]] }}}>test</a>

-e

1 Like
#3

Hey! I like the use of join[] instead of many addsuffix! Very elegant!

Fred

#4

One thing to be careful of when using the +[join[]] technique…

If any of the text “pieces” occurs more than once, like this:

<$let quotedvalue={{{ [["]]  [{!!somefield}] [["]] +[join[]] }}}>

then only the last instance of [["]] will be kept because list items are “dominantly appended” which means that each item must occur only once.

To prevent this, you can use the “=” filter run prefix, like this:

<$let quotedvalue={{{ =[["]]  [{!!somefield}] =[["]] +[join[]] }}}>

In the above example, =[["]] allows both quotes to remain in the list.

In fact, it’s probably best to always use the “=” filter run prefix just to be sure you don’t unintentionally have repeated values, like this:

<$let quotedvalue={{{ =[["]]  =[{!!somefield}] =[["]] +[join[]] }}}>

In this way, if the contents of somefield is actually ", then you will get """ as a result (i.e, a “quoted quote” ) instead of just ".

-e

3 Likes
#5

Excellent tip but I think there is a typo in there. The [{!!somefield}} terms should be [{!!somefield}] .

I spend a lot of time chasing down similar little subtle things like tabs, trailing spaces and em/en dashes looking like hyphens.

/Mike

#6

fixed typos. Thanks.