Multiple Single Select (Always one selected)

[fabdulazeez]

In our system, there are two single select fields with a parent-child relationship. Selection of the parent with single unique child is not possible, because that particular child selection is not possible as its unique and is not available for the currently selected parent and that particular parent selection  is not possible as it has only one child.Is there a solution that allows users to make this selections.

And even if the selection is made possible by default , it creates a locked scenario where the user cannot alter the selection. This occurs because the parent has only one child, leaving no other options available. Is there a solution that allows users to make different selections in this scenario.

[marcus_sommer]

I'm not sure if there ways to get to work in this way but if they will probably have all some side-effects.

I doubt that I would try something in this direction else let the users select what they want. You may support the users by showing them any information of how many values from which field they have selected and this might be to many data to interpret them properly. This may also include some visibility and/or calculation conditions. 

[fabdulazeez]

Thank you for providing this insight. Could you please clarify a bit more on how you envision the implementation of these methods and what specific side-effects you anticipate ?
We need to make the fields single select because the data volume would be overwhelming for users if all or multiple options were chosen. Furthermore, values in each field, such as region and country, holds individual significance.

We could implement visibility conditions for the visualization, such as making it visible only when one option is selected from each field. However, the end user prefers not to have such an experience.

[marcus_sommer]

Thinkable would be to apply any kind of action-stuff to lock and unlock the fields and/or enable/disable the select-only-one feature (I believe it would require extensions).

Another approach may be to restrict the number of dimension-values within the list-boxes by using expressions, like:

if(match(Field, '$(vFieldList)'), Field)

or

aggr(only({< Field = {'$(vFieldList)'}>} Field), Field)

and the expression-logic might be outsourced in variables.

Beside using associated dimensions the filter-logic might be transferred into the expression and the selections are done with unrelated island tables, like:

sum({< Parent = p(IslandParent), Child = p(IslandChild)>} Value)

IMO you should also consider adjustments to the data-model by applying a different type of hierarchy and/or to extend the existing one, for example by adding any kind of extra categories maybe by grouping the parents to countries and regions. Such grouping might be also used to implement a section access and/or user-related dimensions (there might be n parent/child dimensions each one only with a sub-set of values and the other are NULL).