saveWidget doesn't specify a <title> element #289

cpsievert · 2017-11-01T22:39:47Z

And, as consequence, produces unsavory results with pandoc >= 2.0

m <- DT::datatable(mtcars)
htmlwidgets::saveWidget(m, "index.html")
#> [WARNING] This document format requires a nonempty <title> element.
#> Please specify either 'title' or 'pagetitle' in the metadata.
#> Falling back to 'index'

browseURL("index.html")

htmlwidgets:::.pandoc$version
#> ‘2.0.0.1’

BillDunlap · 2017-11-02T21:08:26Z

I noticed the same thing with jjallaire/sigma. I installed pandoc-1.19.2.1 and pandoc-2.0.1 under C:\Pandoc and switched between them by fiddling with htmlwidgets:::.pandoc. When using
saveWidget(selfcontained=TRUE) with pandoc-2.0.1 I got a warning and mangled html file.

> z <- sigma::sigma(system.file("examples/ediaspora.gexf.xml", package = "sigma"))
> htmlFilename <- tempfile(fileext=".html")
> w <- htmlwidgets:::saveWidget(z, file=htmlFilename, selfcontained=TRUE)
[WARNING] This document format requires a nonempty <title> element.
  Please specify either 'title' or 'pagetitle' in the metadata.
  Falling back to 'file2a643ec14d9f'
> writeLines(substring(readLines(htmlFilename, n=10), 1, 50))
&lt;!DOCTYPE html&gt;
<html>
<head>
<meta charset="utf-8" />
<script>(function() {
  // If window.HTMLWidgets is already defined, the
  // new object. This allows preceding code to set
  // initialization process (though none currently
  window.HTMLWidgets = window.HTMLWidgets || {};

Is this because htmlwidgets:::pandoc_self_contained_html claims to pandoc
that its html input file is a markdown file? Pandoc-2.0 seems to balk at this.

  # convert from markdown to html to get base64 encoding
  # (note there is no markdown in the source document but
  # we still need to do this "conversion" to get the
  # base64 encoding)
  pandoc_convert(
    input = input,
    from = "markdown",
    output = output,
    options = c(
      "--self-contained",
      "--template", template
    )
  )

ramnathv · 2017-11-03T00:05:09Z

Fixing the title requirement is straightforward. We can explicitly allow users to specify a title in saveWidget. What should we default it to? Any thoughts @cpsievert.

@BillDunlap based on the output you posted, it seems like pandoc is escaping html tags. I will try to reproduce this with pandoc 2.0.1 and the latest version of htmlwidgets.

BillDunlap · 2017-11-03T01:09:23Z

With pandoc-2.0.1 you also do not get the base64 encoding of the supporting library scripts. My suspicion is that when you claim the input is markdown but it is really html, pandoc-2.0.1 will give you problems. At this point, is pandoc only being used to incorporate the library scripts into the main file and to base64 encode them? If so, we could do that in R code.

…

On Thu, Nov 2, 2017 at 5:05 PM, Ramnath Vaidyanathan < ***@***.***> wrote: Fixing the title requirement is straightforward. We can explicitly allow users to specify a title in saveWidget. What should we default it to? Any thoughts @cpsievert <https://github.com/cpsievert>. @BillDunlap <https://github.com/billdunlap> based on the output you posted, it seems like pandoc is escaping html tags. I will try to reproduce this with pandoc 2.0.1 and the latest version of htmlwidgets. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#289 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ALHWBWzb4eMQy6R_GcUibpHgYFxW7gFCks5syli2gaJpZM4QO7L_> .

ramnathv · 2017-11-03T01:28:20Z

@BillDunlap pandoc is mainly used to inline all dependencies recursively. Doing this in R will take some effort.

kiefersmith · 2017-11-13T21:59:46Z

I am also having this issue. Any updates?

BillDunlap · 2017-11-13T22:39:58Z

I am not very familiar with all of what htmlwidgets can do, but the following function makes a self-contained html file similar to the one pandoc makes if all the required files are *.js files and if there is no need to recursively process the required files. Apply it to the readLInes() of the file that htmlwidgets::saveWidget(selfcontained=FALSE,...) produces, after setting the working directory to dirname() of that html file and then call writeLines() on its output. It uses regular expressions instead parsing the html so it is not robust, but it helped me see what was going on. replaceScriptSrcLines <- function(htmlText) { # replace lines of form # <script src="dir/file.js"></script> # by # <script src="data:application/x-javascript;base64,*BASE64_ENCODED_JSFILE*"></script>" # where *BASE64_ENCODED_JSFILE* is the string returned by base64enc::base64encode("dir/file.js"). # Apply this to readLines() of the file that srcPattern <- "(^.*<script src=\")([^:\"]+.js)(\"></script>.*)" srcLineNos <- grep(srcPattern, htmlText) cap <- strcapture(srcPattern, htmlText[srcLineNos], proto=list(start="", script="", end="")) for(j in seq_along(srcLineNos)) { htmlText[srcLineNos[j]] <- paste0(cap$start[j], "data:application/x-javascript;base64,", base64enc::base64encode(cap$script[j]), cap$end[j]) } htmlText }

…

On Mon, Nov 13, 2017 at 1:59 PM, Kiefer Smith ***@***.***> wrote: I am also having this issue. Any updates? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#289 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ALHWBQ15iRrOuQhKxy2HrVaufIPmElCyks5s2LvUgaJpZM4QO7L_> .

kiefersmith · 2017-11-14T01:24:27Z

I seem to have circumvented the issue via htmltools::save_html(). My issue seems less involve than what others are getting into. Still interesting to dive deeper on some of these functions.

jcheng5 · 2017-11-14T18:52:34Z

I'm going to submit a PR for this (the original issue) today. My proposal is that saveWidget will get a new title parameter that defaults to class(widget)[[1]]. Any objections to that?

jjallaire · 2017-11-14T18:58:24Z

That sounds good to me!

…

On Tue, Nov 14, 2017 at 1:52 PM, Joe Cheng ***@***.***> wrote: I'm going to submit a PR for this (the original issue) today. My proposal is that saveWidget will get a new title parameter that defaults to class(widget)[[1]]. Any objections to that? — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#289 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAGXx45RjeWiYqGdgrscJ_gJoUjWVW0rks5s2eFygaJpZM4QO7L_> .

jcheng5 · 2017-11-15T00:37:31Z

Turns out this is significantly more annoying than we originally thought.

The htmlwidgets::pandoc_self_contained_html function tells pandoc that the input format is markdown. But the actual file is a well-formed .html file, generated by htmltools::save_html. This has two problems.

Any <title> in the input document is ignored (you still get the warning); instead Pandoc wants you to add a yaml header to the input HTML file with a non-empty title or pagetitle field, which then is not actually used in our pandoc template (because its entire contents is $body$ ).
The <!DOCTYPE html> at the top of the input HTML file (rightfully put there by htmltools::save_html) becomes escaped in the output HTML: <!DOCTYPE html>. This behavior is different than pandoc 1.x.

Rather than try to feed pandoc a well-formed HTML document, I think it's a better idea to fork the body of htmltools::save_html, which isn't much anyway, and more carefully generate an input file and template that both pandoc 1.x and 2.0 can be happy with.

cpsievert · 2023-02-08T00:27:26Z

This was fixed by #292

nightroman mentioned this issue Nov 6, 2017

Markdown: recent pandoc --standalone writes not clear warnings about title jgm/pandoc#4048

Closed

wch mentioned this issue Nov 14, 2017

profvis: [WARNING] This document format requires a nonempty <title> element. rstudio/profvis#90

Closed

jcheng5 mentioned this issue Nov 15, 2017

More resilient pandoc self-contained mechanism #292

Merged

jmcphers mentioned this issue Nov 15, 2017

Validate compatibility with Pandoc 2.0 rstudio/rstudio#1756

Closed

lorenzwalthert mentioned this issue Jan 7, 2018

(Pandoc?) warning about nonempty title element tidyverse/reprex#156

Closed

cderv mentioned this issue Apr 1, 2021

pandoc_self_contained_html() does not produce a valid HTML file rstudio/rmarkdown#2087

Open

3 tasks

cpsievert closed this as completed Feb 8, 2023

cpsievert mentioned this issue Feb 8, 2023

Add selfcontained option to save_html() rstudio/htmltools#73

Open

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saveWidget doesn't specify a <title> element #289

saveWidget doesn't specify a <title> element #289

cpsievert commented Nov 1, 2017

BillDunlap commented Nov 2, 2017 •

edited

ramnathv commented Nov 3, 2017

BillDunlap commented Nov 3, 2017 via email

ramnathv commented Nov 3, 2017

kiefersmith commented Nov 13, 2017

BillDunlap commented Nov 13, 2017 via email

kiefersmith commented Nov 14, 2017

jcheng5 commented Nov 14, 2017

jjallaire commented Nov 14, 2017 via email

jcheng5 commented Nov 15, 2017

cpsievert commented Feb 8, 2023

saveWidget doesn't specify a <title> element #289

saveWidget doesn't specify a <title> element #289

Comments

cpsievert commented Nov 1, 2017

BillDunlap commented Nov 2, 2017 • edited

ramnathv commented Nov 3, 2017

BillDunlap commented Nov 3, 2017 via email

ramnathv commented Nov 3, 2017

kiefersmith commented Nov 13, 2017

BillDunlap commented Nov 13, 2017 via email

kiefersmith commented Nov 14, 2017

jcheng5 commented Nov 14, 2017

jjallaire commented Nov 14, 2017 via email

jcheng5 commented Nov 15, 2017

cpsievert commented Feb 8, 2023

BillDunlap commented Nov 2, 2017 •

edited