[QGIS-Developer] How to update change the datasource of already existing layer

[Nyall Dawson]

On Wed, 12 Jun 2019 at 10:09, Ivan Ivanov <suricactus at gmail.com> wrote:
>
> I fixed it. Sorry for the inconvenience:
>
> layer1 = QgsVectorLayer('Polygon?crs=epsg:32612', 'layer2', 'memory')
> layer2 = QgsVectorLayer('Polygon?crs=epsg:32612', 'layer1', 'memory')
>
> print(layer1.source())
> print(layer2.source())
> layer1.setDataSource(layer2.source(), layer2.name(), layer2.dataProvider().name())
> print(layer1.source())

I agree that the results of this output look odd - but what exactly
are you trying to achieve here?

Nyall

>
> On Wed, 12 Jun 2019 at 00:28, Nyall Dawson <nyall.dawson at gmail.com> wrote:
>>
>> On Tue, 11 Jun 2019 at 15:06, Ivan Ivanov <suricactus at gmail.com> wrote:
>> >
>> > Hello,
>> >
>> >
>> > Can you give me some idea why I'm getting two uids in the layer's source? And also how I can fix this because now the layer just disappears from the map canvas. (all layers are isValid() = True)
>> >
>> > oldLayer.source()
>> > # MultiLineString?crs=EPSG:32737&field=fid:integer(0,0)&uid={6cd1f176-9c05-4d2a-961a-3143a8fa422b}
>> >
>> > newLayer = processing.run('save:selectedfeatures', {
>> >     'INPUT': oldLayer,
>> >     'OUTPUT': 'memory:newLayer'
>> > )
>> >
>> > oldLayer.setDataSource(newLayer.source(), oldLayer.name(), newLayer.dataProvider().name())
>> >
>> > newLayer.source()
>> > # MultiLineString?crs=EPSG:32737&field=fid:integer(0,0)&uid={d36aff88-4248-4ffb-be2f-2ac1891ac26d}
>> > oldLayer.source()
>> >
>> > # WRONG, I would expect the same as above. Also, the uid is completely new.
>> > # MultiLineString?crs=EPSG:32737&field=fid:integer(0,0)&uid={d36aff88-4248-4ffb-be2f-2ac1891ac26d}&uid={3422de07-cf38-4249-af55-23c7d9779daf}
>>
>> Hi Ivan,
>>
>> Your code seems incomplete and has some syntax errors -- maybe it
>> wasn't copied correctly? Can you repost please?
>>
>> Nyall