[QGIS-Developer] Cannot load WMS capabilities from WMS provider in QGIS3 from python

[David Marteau]

Ticket filled https://issues.qgis.org/issues/17866

> Le 16 janv. 2018 à 09:18, David Marteau <dmarteau at 3liz.com> a écrit :
> 
> Hi Alessandro
> 
> This is a weird bug, I have also found that once the first request failed, others requests succeed wathever the url or the provider is (tried with wcs and wms).
> When failing, looking on what append wms server  side when we found that no request is sent.
> 
> I fill a ticket on this.
> 
> 
>>> The point is: trying to instanciate  a  wmsprovider will issue a timeout when trying to request the capabilities: the code responsible for that creates its own QEventLoop and manage to do a blocking call (which is expected here). 
>>> Please have a look at https://github.com/qgis/QGIS/blob/master/src/providers/wms/qgswmscapabilities.cpp#L1964 <https://github.com/qgis/QGIS/blob/master/src/providers/wms/qgswmscapabilities.cpp#L1964>.  What we do not understand is why, despite the call of loop.exec() in the c++ code, the request is not processed (my example with the  Q(gs)etworkAccessManager
>>> shows that it should processed)
>>> 
>>> Actually you cannot instanciate properly a QgsProject with a WMS layer.
>>> 
>>> To convince yourself, try to instanciate a QgsProject in python (in a standalone python script) from a .qgs project having a single wms layer: it will fail to instanciate the layer.
>>> 
>> 
>> 
>> Hi David, 
>> 
>> I verified this issue, I'm sorry but I don't have an explanation right away and it looks like a bug, please file a ticket.
>> 
>> 
>> -- 
>> Alessandro Pasotti
>> w3:   www.itopen.it <http://www.itopen.it/>

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