How do I use QDesktopServices::openUrl with 'file:' URL containing '#'?

Question

In my application, I generate a HTML file that I want to open by clicking on a button. So my file is named, for example:

QString file = "F:/the_path/to_the_/generated_html_file.html";

On Windows I change it to:

file = "file:///F:/the_path/to_the_/generated_html_file.html";

so that I can open it with :

QDesktopServices::openUrl(QUrl(file));

and it opens in the default browser.

But when the character # is present in the path or file name, it doesn't work any more and it seems that the URL is truncated just after the #.

For example, if I name the file generated#_html_file.html, I get this error message:

ShellExecute 'F:/the_path/to_the_/generated' failed (error 2).

Why does that happen, and how can I avoid it?

Toby Speight · Accepted Answer · 2015-07-22T14:25:01.663

12

In a URL, # is a character that delimits the 'fragment identifier' from the resource location. To reference a file: URL with a literal #, it needs to be escaped (as %23).

Reference: RFC 1738:

The character "#" is unsafe and should always be encoded because it is used in World Wide Web and in other systems to delimit a URL from a fragment/anchor identifier that might follow it.

As noted by SteveTJS, the static method QUrl::fromLocalFile() is provided for this purpose, so you can write

QDesktopServices::openUrl(QUrl::fromLocalFile(file));

instead of

QDesktopServices::openUrl(QUrl(file));

This will

Prepend the file: protocol identifier and // empty hostname
Convert native path separator to / (if different)
Encode any non-safe characters for URL.

edited Jul 22 '15 at 14:25

answered Jul 22 '15 at 13:03

Toby Speight

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Indeed, I posted my answer at the same time. The function QUrl::fromLocalFile(...) does the work. – SteveTJS Jul 22 '15 at 13:05
@Steve - quite right, I don't use `QUrl` very much, so I'd forgotten that. I've upvoted your answer, and will add a note to mine. – Toby Speight Jul 22 '15 at 14:14

score 6 · Answer 2 · edited Jul 22 '15 at 16:05

6

I just found the solution:

QString file = "F:/the_path/to_the_/generated#_html_file.html";
QUrl url = QUrl::fromLocalFile(file);
// gives url="file:///F:/the_path/to_the_/generated%23_html_file.html";
QDesktopServices::openUrl(url); //works

edited Jul 22 '15 at 16:05

Toby Speight

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answered Jul 22 '15 at 13:04

SteveTJS

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Ah yes - `fromLocalFile()` is there for exactly this kind of conversion. No need for the `QUrl(url)` copy, though? – Toby Speight Jul 22 '15 at 14:11
@TobySpeight No need in QUrl(url) since the url parameter is already good. – SteveTJS Jul 22 '15 at 14:26

How do I use QDesktopServices::openUrl with 'file:' URL containing '#'?

2 Answers2