evaluation in templates

[Mic G77]

Hello,

in the current.html.tmpl, i have written this code:

<td class="stats_data">$current.extraTemp6.raw-$current.extraHumid6.raw</td>

I was  expecting an evaluation of $current.extraTemp6.raw-$current.extraHumid6.raw

but i get (i suppose a string) : 13.7-70.0

How could the template evaluate the expression ?

I think it is possible because in the user_guide ( usr/share/doc/weewx/customizing.htm#Comprehensive_example), I've seen this line :

<td>$hour.start.format("%H:%M")-$hour.end.format("%H:%M")</td>

Thanks in advance,

Mic

[gjr80]

Hi,

What you saw in the template was not an evaluation (arithmetic) as such, but simply showing two times in hour:minute format separated by a hyphen, much like the result from your code. To do in-template arithmetic you need to have some in-line python code to do the arithmetic and assign the result to a variable then use the variable as a tag later in your template. Something like (untested):

#set $my_result = $current.extraTemp6.raw-$current.extraHumid6.raw
<td class="stats_data">$my_result</td>

The above is a very simplistic example (formatting will probably not be what you want) but it gives you a start. You will find in-line python in a number of the templates included with WeeWX.

Gary

[Andrew Milner]

seems a very strange thing to want to evaluate anyway - subtracting a humidity value from a temperature value!!

[Thomas Keffer]

You need to surround the expression with $(...) to get Cheetah to evaluate it, instead of just turn it into HTML. So, you want

$($current.extraTemp6.raw - $current.extraHumid6.raw)

-tk

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[gjr80]

Well I didn’t know that, always thought though there must have been a more direct way, just never found it.

Gary