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Numbers

Decimal number​

NumberField is a generic numeric field that can contain numbers with decimals.

from viktor.parametrization import ViktorParametrization, NumberField


class Parametrization(ViktorParametrization):
    number = NumberField('This is a NumberField')

Slider​

The NumberField can also be shown as a slider using the variant argument:

NumberField('This is a NumberField shown as slider', variant='slider')

Integer​

IntegerField is a specific numeric field that can contain integers only.

from viktor.parametrization import ViktorParametrization, IntegerField


class Parametrization(ViktorParametrization):
    integer = IntegerField('This is a IntegerField')

Setting min/max​

The min and max value of the field can be set using the min and max arguments respectively:

NumberField('X', min=0, max=10)

When the user enters a value that exceeds these bounds, the fields are marked as invalid.

If the value for min or max needs to be calculated 'dynamically' (based on other input fields), one of the below methods can be used.

Depending on other field​

If the value for min or max depends on another numeric field, the easiest solution is to use a Lookup. This looks up the value of the field with given name upon evaluation of the min/max constraint:

from viktor.parametrization import ..., Lookup


class Parametrization(ViktorParametrization):
    param_x = NumberField('X')
    param_y = NumberField('Y', min=Lookup('param_x'))

In case of a nested parametrization structure, the dotted path should be used:

Lookup('tab.section.param_x')

When the Lookup cannot find the target field, a warning is raised and the min/max constraint is set to its default (i.e. min=None, max=None).

Inside a DynamicArray​

If the value for min or max depends on the result of another numeric field within a DynamicArray, a RowLookup can be used. Using the RowLookup, a field of a specific row within the array can be made dependent of another field within the same row:

from viktor.parametrization import ..., RowLookup


class Parametrization(ViktorParametrization):
    array = DynamicArray('Array')
    array.param_x = NumberField('X')
    array.param_y = NumberField('Y', min=RowLookup('param_x'))

Using a function​

The most generic way to dynamically set the min/max value is to use a 'callback function'. Upon evaluation of the min or max constraint, the platform passes the params, entity_id, and entity_name to the custom function:

def param_y_min(params, **kwargs):
    return params.param_x


class Parametrization(ViktorParametrization):
    param_x = NumberField('X')
    param_y = NumberField('Y', min=param_y_min)
tip

All individual kwargs can be added explicitly in the signature if needed:

def param_y_min(params, entity_id, entity_name, **kwargs):
    ...

For constraints that have to be applied to fields within a DynamicArray, make sure that the callback function returns a list of the constraint values, one for each row in the array. The length of this list must be equal to the number of rows in the array, otherwise (a warning is logged and) the constraint is ignored:

def param_y_min(params, **kwargs):
    return [row.param_x for row in params.array]


class Parametrization(ViktorParametrization):    
    array = DynamicArray('Array')
    array.param_x = NumberField('X')
    array.param_y = NumberField('Y', min=param_y_min)

When the value for min/max depends on data of another entity, the entity_id can be used to share data between entities using the API.