field value is a whitespace

[wtaylor149]

I have a field that sometimes has only what appears to be a whatspace.  How would I replace the existing whitespace with a value of "none"?

[thambisetty]

| rex field=yourfield “/s/^\s$/yourvaluetoreplace/g”

Note: dont copy paste. The above solution works only if there is whitespace

[wtaylor149]

Thanks for the quick response but that did not work, even after I fixed the sed structure.