More to the point, why is atilkan coding `<!-- <input
value='{{.nonExistingData}}'> -->` an HTML comment when golang templates is
a preprocessor language.that is going to strip HTML comments? If he is
retaining code in the template for future reference, then why not use a
template comment {{ /* */ }} instead of an HTML comment. Anyone familiar
with PHP is accustomed to dealing with this situation where HTML,
Javascript & more has a conflict with the PHP language (e.g. passing quotes
thru PHP).
On Tue, Dec 31, 2024 at 12:19 AM Kurtis Rader <kra...@skepticism.us> wrote:
> Argh! I just realized my reference to the comment about the html/template
> "HTML" type handling of comments isn't really relevant. The issue is that
> the html/template package doesn't inhibit substitution inside a semantic
> HTML comment. It does elide comments from the generated output but does
> attempt to perform substitutions within the HTML comment. This doesn't
> surprise me but it also wasn't obvious to me from a quick reading of the
> package documentation. Perhaps the documentation would benefit from the
> addition of some clarifying text on this point. You have to actually
> convert the HTML comment into a literal string. For example, changing
>
> <!-- <input value='{{.nonExistingData}}'> -->
>
>
> into
>
> {{ "<!-- <input value='{{.nonExistingData}}'> -->" }}
>
>
>
> On Mon, Dec 30, 2024 at 11:31 PM Kurtis Rader <kra...@skepticism.us>
> wrote:
>
>> You should always include the full error message (and backtrace if
>> available) as well as telling us the relevant version of Go you used to
>> compile your program and the particular package you believe is the source
>> of the problem. A minimal reproducible example is also a good idea if
>> feasible.
>>
>> In this case we're guessing you're using https://pkg.go.dev/html/template
>> but we shouldn't have to guess. Jon guessed that the error is from a
>> Javascript interpreter, and not a Go stdlib package, because of the lack of
>> context and the wording of the partial error message you gave us. I'm
>> guessing the error is from src/text/template/exec.go:
>>
>> s.errorf("can't evaluate field %s in type %s", fieldName, typ)
>>
>>
>> Note that html/template delegates the actual substitution to
>> text/template.
>>
>> The documentation for html/template (
>> https://pkg.go.dev/html/template@go1.23.4) explicitly states that the
>> HTML type should not contain comments:
>>
>> HTML encapsulates a known safe HTML document fragment. It should not be
>> used for HTML from a third-party, or HTML with unclosed tags or comments.
>> The outputs of a sound HTML sanitizer and a template escaped by this
>> package are fine for use with HTML.
>>
>> Whether that package comment is relevant is unclear since you didn't
>> provide enough information for us to do more than make educated guesses.
>>
>> I took the first example program at
>> https://pkg.go.dev/html/template@go1.23.4 and inserted your string as
>> the first line of the "const tpl = ..." definition. That resulted in this
>> runtime failure:
>>
>> 2024/12/30 23:28:23 template: webpage:2:21: executing "webpage" at
>> <.nonExistingData>: can't evaluate field nonExistingData in type struct {
>> Title string; Items []string }
>>
>>
>> Does that look like the error you're seeing?
>>
>>
>> On Mon, Dec 30, 2024 at 11:23 AM atilkan <emrahatil...@gmail.com> wrote:
>>
>>> Hi,
>>> I am trying to add html comment (yes, they will be removed). I believe
>>> it strips the comments after processing the template. If you put
>>> non-existing property inside html comments, it throws error.
>>> Maybe better to strip comments before processing the template?
>>>
>>> `<!-- <input value='{{.nonExistingData}}'> -->`
>>>
>>> I would paste the whole error but you have to search needle in haystack.
>>> Basically says* "can't evaluate field nonExistingData"*.
>>>
>>>
>>> Have a nice day.
>>>
>>> --
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>>>
>>
>>
>> --
>> Kurtis Rader
>> Caretaker of the exceptional canines Junior and Hank
>>
>
>
> --
> Kurtis Rader
> Caretaker of the exceptional canines Junior and Hank
>
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