MATLAB: Checking if a nested field exists in a structure

struct

I am building a structure whose fields and subfields are nested structures. I would like to cycle through a subfield, determine if any values have been assigned yet, and if not, assign a value to the end of an array. Here is an example in which I am checking how many potato dishes guests are bringing to a potluck Thanksgiving dinner. Is there a better way to do this? My real dataset has many more fields than this example. 
potatoList = {'Yam', 'White', 'Candied'};
for iPerson = 1:4 % cycle through guests
    for iPotato = 1:length(potatoList)
        isFirst = false; % Is this the first entry for a given type of potato or not?
        if ~exist('Thanksgiving', 'var') % Haven't even created the structure yet
            isFirst = true;
        else % Structure exists, but subfield may not
            if ~isfield(Thanksgiving, 'Potato')
                isFirst = true;
            else
                if ~isfield(Thanksgiving.Potato, potatoList{iPotato})
                    isFirst = true;
                end
            end
        end
        if isFirst
            iValue = 1; % The first time, the index starts at one
            % Placeholder for nested subfield before value is assigned, to avoid
            % error due to field not existing yet
            Thanksgiving.Potato.(potatoList{iPotato}).number = []; 
        else
             % After the first time, the index starts at the end of the array
            iValue = length(Thanksgiving.Potato.(potatoList{iPotato}).number) + 1;
        end
        % Assign example values to array
        Thanksgiving.Potato.(potatoList{iPotato}).number(iValue) = ...
            round(rand(1)*10); % Number of potato dishes someone is bringing
    end
end

Best Answer

I found a useful function isnestedfield.m in this answer provided by Thorsten, so I will close out this question.
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