How do I check If a map entry doesn't exist for a given sender?

by Tiago Bértolo   Last Updated August 13, 2019 20:28 PM

I have a map such as:

mapping (address => bytes32) private myMap;

Later in the code, in a function, I want to ensure my sender already has an entry in that given map.

Can I do this?

require(!myMap[msg.sender], 'there is an entry in the map already!')

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