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From: Neel Patel <neel.patel@enterprisedb.com>
Date: Fri, 1 Jul 2016 10:13:42 +0530
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Subject: Re: [pgAdmin4][runtime]: Download feature in runtime
To: Dave Page <dpage@pgadmin.org>
Cc: pgadmin-hackers <pgadmin-hackers@postgresql.org>
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Hi Dave,

On Thu, Jun 30, 2016 at 7:31 PM, Dave Page <dpage@pgadmin.org> wrote:

> Hi
>
> On Thu, Jun 30, 2016 at 10:42 AM, Neel Patel
> <neel.patel@enterprisedb.com> wrote:
> > Hi,
> >
> > Please find attached patch file for initial version of download file in
> > runtime application.
>
> I've attached an update with some improved messages, and setting the
> progress dialogue to be modal (seeing as we cannot have multiple
> downloads, and it's easy to lose the dialogue).
>
> > With this patch, we have implemented two features.
> >
> > Feature 1 :- Normal "Download file" from runtime application
> >
> > Previously "Download file" was not implemented in runtime application.
> > With this patch file, we have handled Qt signal for download file
> properly.
>
> This seems to work fine. I did get one crash (after I cancelled a
> download, then tried it again), but I couldn't reproduce that.
>

Okay. I will try to reproduce the issue and also i will try to review the
code again if i can find something regrading crash.


>
> > Feature 2 :-   "download" attribute support for 'a' tag for client side
> > download
> >
> > As per our knowledge, webkit has not implemented the download attribute
> at
> > 'a' tag.
> > Currently it shows under development from below link.
> >
> > https://bugreports.qt.io/browse/QTBUG-47732
> >
> > We did not found any signal in Qt for download attribute feature but to
> > implement this feature in runtime application, we added one workaround to
> > make it work with download CSV file.
> >
> > When we click on download buttons, we are getting Qt signal
> "urlLinkClicked"
> > and in that url we are finding "data:text/csv" from encoded URL generated
> > from sqleditor. Once we found that tag then we are decoding the csv data
> and
> > writing to file.
> >
> > Is that right approach ? Should we add our own custom mime-type to
> header ?
> > Let us know your thoughts on this feature.
>
> This doesn't work so well, for a number of reasons:
>
> 1) QT Creator is complaining that your regexp contains an invalid
> escape sequence (line 546).
>

I will fix.

>
> 2) The default file name seems to be the entire data blob. I would
> suggest making the file name "download.csv" if we don't know anything
> better. The "csv" part should be taken from the mime type (see below)
>
> 3) Should we handle all "data:" downloads in this way? Taking the file
> type and default extension from the mimetype offered.
>

We can handle all "data:" download. We will extract the filename and
extension from mime type.
As i know, Qt provides QUrlQuery class which will be useful to find the key
value pair. I will test and let you know.

e.g. If we have header as below

"data:text/csv;charset=utf-8;Content-disposition:attachment;filename=download.csv;"