[Qgis-developer] New API: get attribute values from a PostGIS layer

[Stéphane Henriod]

Thanks Nathan,

this has indeed solved the problem.

I just updated Qgis on my Ubuntu but apparently the nightly builds haven't
taken your change into account yet. I'll give it another try in a few days

Cheers

Stéphane

--
"Le mot progrès n'aura aucun sens tant qu'il y aura des enfants malheureux"
-- Albert Einstein

"A journey does not need reasons. Before long, it proves to be reason
enough in itself. One thinks that one is going to make a journey, yet soon
it is the journey that makes or unmakes you." -- Nicolas Bouvier

Photos de voyages, photos de montagne: http://www.henriod.info


On Thu, Jul 18, 2013 at 12:14 AM, Nathan Woodrow <madmanwoo at gmail.com>wrote:

> You will need to get the nightly builds I'm not sure what time they are
> done for Ubuntu, but If you would like you can add this code (before any
> PyQt4 imports) into your code in the meantime:
>
> import sip
> try:
>     apis = ["QDate", "QDateTime", "QString", "QTextStream", "QTime",
> "QUrl", "QVariant"]
>      for api in apis:
>         sip.setapi(api, 2)
> except ValueError:
>     # API has already been set so we can't set it again.
>     pass
>
> That will set the API version so you don't need to update just yet.
>
> - Nathan
>
>
>
> On Thu, Jul 18, 2013 at 8:10 AM, Stéphane Henriod <stephanebek at gmail.com>wrote:
>
>> Thanks a lot for your answer, I will try tomorrow.
>>
>> How can I check if my installed version is already taking your change
>> into account?
>>
>> Cheers
>>
>> Stéphane
>>
>> Le 18 juil. 2013 à 00:05, Nathan Woodrow <madmanwoo at gmail.com> a écrit :
>>
>>  Hey Stephane,
>>
>> This is because your standalone script doesn't use the new SIP API.  I
>> pushed a change last night so that now importing qgis will set the API to
>> version to.  All you need to do is make sure you import it first before any
>> of the PyQt4 modules are.
>>
>> Before:
>> from PyQt4.QtCore import *
>> from qgis.core import *
>>
>> After
>> from qgis.core import *
>> from PyQt4.QtCore import *
>>
>>
>> If you import PyQt4 first it will set the API to version 1 which you
>> can't change after.
>>
>> - Nathan
>>
>>
>> On Thu, Jul 18, 2013 at 5:13 AM, Stéphane Henriod <s at henriod.info> wrote:
>>
>>> Dear all
>>>
>>> I am trying to get into the new 2.0 API and am still facing issues for
>>> very basic stuff: getting the values of the attributes out of a PostGIS
>>> layer.
>>>
>>> Basically, it works (with the almost same code) in the Qgis python
>>> console, but I don't manage to get it to work in a stand-alone script.
>>>
>>> What I have so far is a PostGIS layer, that I load with:
>>>
>>> *uri = QgsDataSourceURI()
>>>> uri.setConnection('localhost', '5432', 'db_name', 'user_name',
>>>> 'password')
>>>> uri.setDataSource('my_schema', 'my_table', 'the_geom')
>>>>
>>>> my_layer = QgsVectorLayer(uri.uri(),'myhospitals','postgres')
>>>> *
>>>
>>>
>>> A quick test shows me that the layer has been successfully loaded:
>>>
>>> *if not my_layer.isValid():
>>>>     print "Layer failed to load!"
>>>> else:
>>>>     print "Layer loaded successfully"
>>>> *
>>>
>>>
>>> I would assume that
>>>
>>> *for elem in my_layer.getFeatures():*
>>>> *    print elem.attributes()*
>>>>
>>>
>>> should return the attributes in a usable format but, instead, I get:
>>> *
>>> *
>>>>
>>>> *[<PyQt4.QtCore.QVariant object at 0xad37aca4>, <PyQt4.QtCore.QVariant
>>>> object at 0xad37acdc>, None, <PyQt4.QtCore.QVariant object at 0xad37ad14>]
>>>> *
>>>> *[<PyQt4.QtCore.QVariant object at 0xad37aca4>, <PyQt4.QtCore.QVariant
>>>> object at 0xad37acdc>, <PyQt4.QtCore.QVariant object at 0xad37ad14>,
>>>> <PyQt4.QtCore.QVariant object at 0xad37ad4c>]*
>>>> *[<PyQt4.QtCore.QVariant object at 0xad37aca4>, <PyQt4.QtCore.QVariant
>>>> object at 0xad37acdc>, <PyQt4.QtCore.QVariant object at 0xad37ad14>,
>>>> <PyQt4.QtCore.QVariant object at 0xad37ad4c>]*
>>>> *[<PyQt4.QtCore.QVariant object at 0xad37aca4>, <PyQt4.QtCore.QVariant
>>>> object at 0xad37acdc>, <PyQt4.QtCore.QVariant object at 0xad37ad14>,
>>>> <PyQt4.QtCore.QVariant object at 0xad37ad4c>]*
>>>>
>>>
>>> Does anyone have an idea where the problem could lie?
>>>
>>> For those who speak French, the question is posted here as well:
>>> http://www.forumsig.org/showthread.php/37178-Nouvelle-API-r%C3%A9cup%C3%A9rer-les-valeurs-attributaires
>>>
>>> I am using Qgis 1.9.0 with Python 2.7 on Ubuntu 13.04
>>>
>>> Thanks in advance for ideas and comments...
>>>
>>> Cheers
>>>
>>> Stéphane
>>> --
>>> "Le mot progrès n'aura aucun sens tant qu'il y aura des enfants
>>> malheureux" -- Albert Einstein
>>>
>>> "A journey does not need reasons. Before long, it proves to be reason
>>> enough in itself. One thinks that one is going to make a journey, yet soon
>>> it is the journey that makes or unmakes you." -- Nicolas Bouvier
>>>
>>> Photos de voyages, photos de montagne: http://www.henriod.info
>>>
>>> _______________________________________________
>>> Qgis-developer mailing list
>>> Qgis-developer at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>
>>>
>>
>
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