Dynamically create parameters

🗪 Support (Q&A)
1

Hello,

How can I dynamically create parameters based on previous user input?
For example, if parametera options are ‘single’ and ‘double’,
I would like to generate one new parameter if the user chooses single and two new parameters if the user chooses double.
I tried to use a call back function and then an if statement but it didn’t work.

Thanks for your help!

def get_parametera_options(params, **kwargs):
    if params.parametera == 'Single':
        return ['1']
    if params.parametera == 'Double':
        return ['2']
    
class Parametrization(ViktorParametrization): 
    parametera = OptionField('Type', options=['Single', 'Double'])
    # if user chooses Single, I want to generate parameter b
    # if user chooses Double, I want to generate parameter c and d
    # but I don't need parameter d to show if it is single
    # Calling get_parametera_options doesn't work
2

Hi Melissa,

Welcome on the forum!

You can dynamically set the visibility of a field to achieve this:

https://docs.viktor.ai/docs/create-apps/user-input/hide-field#using-a-function

3

Hi, thank you for your reply.

It seems that in the provided example, the parameter is hidden depending of the boolean value. In my case, I would like to hide one or more parameters if the value is ‘single’ (because actually I also have a triple option so it is not just boolean).

Is there a way to have it visible base on the string value selected by the user?

Thank you

4

Hi Melissa,

The function provided in the example can be altered as you like. For example, you may assert string values like this:

def param_y_visible(params, **kwargs):
    return params.param_x != "Single"  # returns False if param_x is "Single"
5

Hi, it works great!
Thank you