node.js - DynamoDB conditional update using nodejs -


how conditional update item in dynamodb using nodejs? if exists, increment alone - working expected. struggling in, when item not exists, need add , next iteration onwards increment. got error "the provided expression refers attribute not exist in item".

function increment(data, cb) {     const opt = {         key: {             id: {s: id},             datekey: {s: data.dateval}         },         expressionattributevalues: {             ':counter': {n: '' + 1},             ':val1': {s: data.val1},             ':val2': {s: data.val2}         },         updateexpression: 'set counter=counter+:counter, val1=:val1, val2=:val2',returnvalues: 'updated_new',         tablename:tablename     };      db.updateitem(opt, (err, data) => {         if (err)             return cb(err);          const counter = getcounter(data.attributes); //private method         return cb(null, counter);     }); }


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