Error converting `big.Rat` to `float`

support
1

Hello.

With v0.123 update I’m getting the following error while generating a site:

error calling partial: "…/layouts/partials/figure.html:21:21": execute of template failed: template: partials/figure.html:21:21: executing "partials/figure.html" at <float .>: error calling float: unable to cast big.Rat{a:big.Int{neg:false, abs:big.nat{0x3}}, b:big.Int{neg:false, abs:big.nat{0xa}}} of type big.Rat to float64

What I’m doing is parsing an image EXIF data:

{{ with .file }}
…
	{{ with .Exif }}
…
		{{ with .Tags.ExposureTime }}
			{{ $exposure := 0 }}
			{{ if ( hasPrefix . "1/" ) }}
				{{ $exposure = ( div 1 ( float ( strings.TrimPrefix "1/" . ) ) ) }}
			{{ else }}
				{{ $exposure = ( float . ) }}
			{{ end }}
…

The error happens on the {{ $exposure = ( float . ) }} line.

I’m not sure why this error happens and why a rational number, 0.3 in this case, cannot be converted into a floating point number. With v0.122 it worked just fine.

Any ideas please?

Thank you.

2

Can you upload (do not cut/paste) an image that’s triggering this?

3

Within the folder that triggers this failure I see 3 images with an exposure of 0.3:

https://natalenko.name/myfiles/images.zip

Does this help?

4

Yes, it helps. The problem is with these images, not the Hugo version. I get the same error with DSC_0171.JPG when running v0.122.0.

Running exiftool:

Exposure Time : 0.3

There’s no way that ratio begins with a 1, unless its 1/3.3333333333333333. Maybe the ratio is 3/10, in which case float ain’t gonna work.

5

The ratio doesn’t begin with 1, the code directly tries to convert 0.3 to float. Why this is not going to work? I don’t understand your answer, sorry. I have these very pictures converted with existing code in v0.122 just fine, the result is visible here: Львів | post-factum's notes

6

With your code:

{{ with resources.Get "DSC_0171.JPG" }}
  {{ with .Exif }}
    {{ with .Tags.ExposureTime }}
      {{ $exposure := 0 }}
      {{ if ( hasPrefix . "1/" ) }}
        {{ $exposure = ( div 1 ( float ( strings.TrimPrefix "1/" . ) ) ) }}
      {{ else }}
        {{ $exposure = ( float . ) }}
      {{ end }}
    {{ end }}
  {{ end }}
{{ end }}

Start building sites … 
hugo v0.122.0-b9a03bd59d5f71a529acb3e33f995e0ef332b3aa+extended linux/amd64 BuildDate=2024-01-26T15:54:24Z VendorInfo=gohugoio

Total in 28 ms
Error: error building site: render: failed to render pages: render of "home" failed: "/home/jmooring/code/hugo-testing/layouts/_default/home.html:24:25": execute of template failed: template: _default/home.html:24:25: executing "main" at <float .>: error calling float: unable to cast big.Rat{a:big.Int{neg:false, abs:big.nat{0x3}}, b:big.Int{neg:false, abs:big.nat{0xa}}} of type big.Rat to float64

Notice the version. This isn’t anything new.

7

No, it does not.

Try this:

{{ with resources.Get "DSC_0171.JPG" }}
  {{ with .Exif }}
    {{ with .Tags.ExposureTime }}
      {{ . | string | warnf "%#[2]v (%[2]T) [%[1]d]" math.Counter}}
    {{ end }}
  {{ end }}
{{ end }}

What do you get in the console?

“3/10” (string)

See what I mean?

8

OK, I get the same error too with older versions after wiping the generated resources.

Any idea how to approach this conversion correctly then?

9

Why not just display the ratio? An exposure time of 1/3 is accurate. An exposure time of 0.333333 is only sort-of accurate.

10

I’d like to have the exposure converted to float to display it differently later depending on whether it is greater than 1 second or it is less than 1 second.

11

Then you’re going to have to test for data type, look for a /, split, divide.

12

OK, I’ve ended up with this ATM:

		{{ with .Tags.ExposureTime }}
			{{ $exposure := 0 }}
			{{ if ( strings.Contains . "/" ) }}
				{{ $fraction := ( split . "/" ) }}
				{{ $a := ( float ( index $fraction 0 ) ) }}
				{{ $b := ( float ( index $fraction 1 ) ) }}
				{{ $exposure = ( div $a $b ) }}
			{{ else }}
				{{ $exposure = ( float . ) }}
			{{ end }}
			{{ if ( ge $exposure 1 ) }}
				{{ $title = ( print $title " | " $exposure " s") }}
			{{ else }}
				{{ $title = ( print $title " | 1/" ( math.Round ( div 1 $exposure ) ) " s") }}
			{{ end }}
		{{ end }}

This does seem to work, the build succeeds, although I haven’t checked the correctness of the result with all the images.

Thank you.

13

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