Whether the account a record names is a master's, for every record in one read.

:field names the attribute holding the user id:

calculate :author_master?, :boolean,
          {MishkaCmsCore.Accounts.Calculations.ByMaster, field: :author_id}

Load it beside the account relationship and pass both to MishkaCmsCore.Accounts.Helper.who/4. A record with no id in :field is false.