Make a field required based on the value in other filed

[Ratna Kumar Lekkala]

I have to make a field required based on the value in another field. We have scriptrunner add-on. What is the simplest and best way to achieve this?

Help Please

[Steven F Behnke]

The included Behaviors module can do this or you can use a Script Validator. The Simple Script Validator includes several examples. 

[Ratna Kumar Lekkala]

I cannot do using behaviors module as it does not have condition options based on existing fields (it has a ton of current user and workflow action ans step options but no option for if some field has some value!)

And from the examples provided in Script Validator I cannot find any thing that I can understand/convert for my case.

Can you provide me a sample syntax for  this logic?

IF dropdown_field = option3 or option4 then Text_field =Required END IF