[Qgis-user] [QGIS-Developer] Python Implementation of QgsNetworkContentFetcher

[Nyall Dawson]

On Wed, 27 Nov 2019 at 00:44, Denis Rouzaud <denis.rouzaud at gmail.com> wrote:
>
> Hi,
>
> Jumping late but we use the work from NAM Alessandro did in a couple of locator filters.
> https://github.com/opengisch/qgis-swiss-locator/blob/master/swiss_locator/core/network_access_manager.py
>
> I believe I have done very very few adaptations/fixes to the original work and it works like a charm.

Not quite. It works in some circumstances, but it uses an event loop.
So if you run it on the main thread, you're potentially doing an
effective call to QApplication.processEvents, which can lead to all
sorts of crashes. That said, it's generally a safe approach to use for
QGIS <= 3.4... just don't use it in any code which relates to
rendering!

>
> I had in mind to bring this as is within QGIS core for some time. The main point being for us the blocking request rather than authcfg.

That's EXACTLY what QgsBlockingNetworkRequest is -- please don't
re-re-implement this!

Nyall


>
> Denis
>
> Le mar. 26 nov. 2019 à 15:36, C Hamilton <adenaculture at gmail.com> a écrit :
>>
>> Thanks everyone. This gives me some good ideas. These are the possible solutions:
>>
>> 1. Write a python implementation of QgsNetworkContentFetcher or QgsBlockingNetworkRequest. With this I could look at the QGIS version and if it is 3.10 or greater import the core method; otherwise, import the python implementation.
>> 2. Use the old Boundless implementation if it still works in QGIS 3.
>> 3. Use QgsFileDownloader and save it as a temporary file before processing.
>>
>> Calvin
>>
>> On Tue, Nov 26, 2019 at 2:29 AM Alessandro Pasotti <apasotti at gmail.com> wrote:
>>>
>>>
>>>
>>> On Tue, Nov 26, 2019 at 8:22 AM Richard Duivenvoorde <rdmailings at duif.net> wrote:
>>>>
>>>> On 26/11/2019 00.06, Nyall Dawson wrote:
>>>>
>>>> > There's not. But there's the ex-boundless "networkaccessmanager"
>>>> > implementation that supports authcfg, which you can find at
>>>> > https://github.com/north-road/qgis-redistricting-plugin/blob/master/redistrict/linz/networkaccessmanager.py
>>>> > (and other projects -- as far as I'm aware there's no real upstream
>>>> > for this... Alessandro?).
>>>>
>>>> I used this Boundless thingie for several plugins now (original source
>>>> is now pointing/redirecting to planetlabs [0]).
>>>
>>>
>>> Yes, that's the "upstream" but I don't know if that one is maintained anymore.
>>>
>>> Btw, there is also a specialized class for sync/async downloads that supports authcfg: https://qgis.org/api/classQgsFileDownloader.html#details
>>>
>>>
>>>>
>>>>
>>>> I think we already discussed several times that it would be good to
>>>> incorporate this into a commons lib for QGIS. But if I'm correct the
>>>> actual interface was not exactly what some wanted, and if I recall
>>>> correct Nyall tried to pull this into c++ but hit some multithreading
>>>> issues.
>>>>
>>>> But as Nyall says: I think this is a great lib to use in a plugin (also
>>>> because it used the QgisNetwork-stuff, so you can receive the signals
>>>> from it or log the precise urls, like we do in the QGISnetworklogger
>>>> plugin [1]
>>>>
>>>> Regards,
>>>>
>>>> Richard Duivenvoorde
>>>>
>>>> [0]
>>>> https://github.com/planetfederal/lib-qgis-commons/blob/master/qgiscommons2/network/networkaccessmanager.py
>>>> [1] https://github.com/rduivenvoorde/qgisnetworklogger
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>>>
>>>
>>>
>>> --
>>> Alessandro Pasotti
>>> w3:   www.itopen.it
>>
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