[QGIS-Developer] How to retrieve enum-input value in processing

[Richard Duivenvoorde]

Hi Etienne,

Ah yes, thanks I see. Your issue is exactly I'm asking for...

I'm on master, and I tested the expression_enum2.txt from the PR of
Nyall. It "works".
But the fact that you you have to do a CASE WHEN in an expression
becomes harder when you have a dropdown with a lot of (changing in time)
options. You will have to keep your CASE WHEN in sync with those values

I think using a dropdown/enum in a model is an usefull input.

Should I create a Feature Request from the Issue? Or add it to this issue?

Regards,

Richard Duivenvoorde

On 13/12/2019 14.34, Etienne Trimaille wrote:
> On which QGIS version are you?
> 
> I made this ticket a few weeks ago. You will see that the enum will give
> its index and not the string as you can think.
> https://github.com/qgis/QGIS/issues/32452
> 
> Nyall did some PR in 3.11.
> 
> You need to use a CASE WHEN in your expression. You can open Nyall's
> model to check.
> 
> Le ven. 13 déc. 2019 à 12:25, Richard Duivenvoorde <rdmailings at duif.net
> <mailto:rdmailings at duif.net>> a écrit :
> 
>     Just received a question from a user:
> 
>     He has a small processing model and wants to use an 'enum' (text) input
>     in the model as value for a new column. Which in the column  is created
>     by the 'field calculator' algorithm.
> 
>     But we cannot find out how to get the 'chosen' value out of the
>     'enum'-input (which are always 'strings'). Whatever we try the value of
>     the new column records are always NULL
> 
>     To reproduce:
>     - create an fresh model with an input vector layer
>     - create in 'enum' input call it 'choice' with 2 values 'blue', 'red'
>     - use the 'field calculator' algorithm to create a new string field
>     we thought that '@choice' would be the Formula (being the value of the
>     'choice' input...
> 
>     BUT: the column is never filled with 'red' or 'blue'...
> 
>     Anybody a clue?
> 
>     Regards,
> 
>     Richard Duivenvoorde
> 
>     ps looking into
>     https://qgis.org/api/classQgsProcessingParameterEnum.html#details
>     and
>     https://qgis.org/api/qgsprocessingparameters_8cpp_source.html
>     dit not reveal anything to me...
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