Flowable-Design Form Validation

Hi Team,

I am using flowable design to build form . there I stuck in one validation.

Case : In Flowable-form I have one Dropdown Select (component) and one Textbox. now I want to validate the Textbox based one Dropdown value.

Dropdown contains different values like [a,b,c,d]. I need to validate Textbox based on value [a,b,c,d]. For example: if dropdown value is ‘a’ then textbox can contain string of 10 letter. if dropdown value is ‘b’ then textbox can contain string of 20 letter.

Thanks in advance. Please suggest any solution flowable provide to handle this kind of scenario.