SP 2010: Make managed metadata field mandatory on condition

Question

I've a list where there is a choice field A and a metadata field B. I want the metadata field B to be a required field if an option xyz is selected on the choice field A.

How can this be achieved?

Answer 1

SharePoint tries to execute a user-defined function called PreSaveAction before an item is saved. You can use that function to validate your data.

Here is a bit of code that should give you a good starting point:

function PreSaveAction(){
  if(jQuery("select[title=A]").val() == "xyz"){
    if(jQuery("div[title=B] > div > .valid-text").length){
      return true
    } else {
      alert("Value in B missing!")
    }
  } else {
    return true
  }
}