[QGIS-Developer] QGIS3 - processing python script. Read features from output layer

[Nyall Dawson]

On 16 February 2018 at 04:36, kimaidou <kimaidou at gmail.com> wrote:
> Hi all,
>
> I have a simple processing python alg which
> * generates a buffer with qgis:buffer
> * use qgis:fieldcalculator to add an buf_area field -> the output vector of
> my alg is this buffer+new field.
>
> I would like to parse the features of the output vector in order to gather
> some information and put it in a new string output. I have not been able to
> get the layer object to perform a getFeatures on it.
>
> See the code
> http://paste.debian.net/1010463/
>
> In line 32, my blayer is None
> I think I am not using the good way to get the output vector layer features?
> I tried to use the same way as for reading an input layer, but oviously it
> is different.

blayer = QgsProcessingUtils.mapLayerFromString( area_result[ 'OUTPUT'
]), context )

I'm thinking of adding a shortcut for this to the context, e.g.:

blayer = context.getMapLayer( area_result['OUTPUT'] )

What do you think?

Nyall