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UI.Next templating type provider requires well-formed HTML
websharperui.next templating

I keep getting this build error:

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error FS3033: The type provider 'WebSharper.UI.Next.Templating.TemplateProvider' reported an error: Unexpected DTD declaration. Line 1, position 12.

The line number and position are not helpful, because this is not where the problem is.

It seems the cause is that my HTML is not well-formed. HTML5 does not require the document to be well-formed, but this type provider apparently does.

There are two examples that have bitten me:

  • The <link> element needs to be closed.
  • Boolean attributes need a value.

For example, this produces the error:

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<link rel="stylesheet" href="/css/foundation.css">

But this is OK:

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<link rel="stylesheet" href="/css/foundation.css" />

And this produces the error:

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<nav class="top-bar" data-topbar role="navigation">

But this is OK:

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<nav class="top-bar" data-topbar="" role="navigation">

I guess I could live with this, but could the type provider be enhanced so that I don't need to?

.

For what it's worth, I also encountered the same problem with other elements that HTML5 doesn't require to close, such as <img> or <br> (TemplateProvider demands them both to be closed). More importantly, I discovered that if you delete the <!DOCTYPE> line from the beginning of the HTML file, the "Unexpected DTD declaration" error message will be replaced by useful ones pointing out which tags aren't closed and where. EDIT: How do I newline on FPish? From quoting the parent it seems that two newlines should suffice.

By on 8/24/2015 12:51 AM ()

That's a good discovery! This works for me too. Thanks.

By on 8/24/2015 11:49 AM ()

Will check into this, should be fairly quick to adjust the parser.

By on 8/21/2015 4:48 PM ()

Also, if you have a <script> element containing some JavaScript code, and that code contains a comparison using >, this produces an error too. The type provider parser should ignore anything inside a <script> element.

By on 8/27/2015 10:57 AM ()

I believe you can write the <script> blocks in your UI.Next template as follows to get rid of the validation error (and this should still work when we relax the parser as I indicated above):

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<script>
//<![CDATA[
    ...code...
//]]>
</script>
By on 8/27/2015 11:06 AM ()

Actually, I'm not sure it did work. The type provider no longer complained, but the JavaScript seemed to be ignored completely, as if I'd commented it out. Anyway, I placed it in a js file instead, which works.

By on 8/28/2015 1:56 AM ()

Yes that works, thanks.

By on 8/27/2015 11:18 AM ()

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