CODEWITHSUNDEEP
javascriptcurryinglodash
philipjkim
philipjkim

Reputation: 4149

Function using _.curry does not work as expected

I made a function that checks whether all elements in userRequest array are in whitelist array, using lodash.

The implementation is:

var isValidRequest = function (whitelist, userRequest) {
  return _.isArray(userRequest) && _.all(userRequest, _.curry(_.contains)(whitelist));
};

And made some tests to prove the function work properly:

describe('#isValidRequest', function () {
  it('should return true if all elements in userRequest are in whitelist', function () {
    var whitelist = ['a', 'b', 'c'];
    var userRequest = ['a', 'c'];
    isValidRequest(whitelist, userRequest).should.eql(true);
  });

  it('should return false if any element in userRequest are not in whitelist', function () {
    var whitelist = ['a', 'b', 'c'];
    var userRequest = ['a', 'd'];
    isValidRequest(whitelist, userRequest).should.eql(false);
  });
}

Those two tests passed. But when I add a test using real-world data, it failed:

it('should return true if all elements in userRequest are in whitelist (with real data)', function () {
  var whitelist = [
    '88096706899774400',
    '88096698426400385',
    '88354827595032721',
    '88770059167850369',
    '88770060663799793',
    '88770086312254177',
    '88775479126833601',
    '88810673591548449',
    '88911136544698224',
    '88911143320755648',
    '89018389627510081',
    '89091351154758240',
    '89138464836818065',
    '89183114982564704',
    '89244113023388657',
    '89295369695148528',
    '89301959129114097',
    '89504545841807728',
    '89534114665094448',
    '89606610296086240',
    '89641336900131600',
    '89731870992552785',
    '89738745919815345',
    '89823303352910497',
    '89840086806894128',
    '89845003632280944',
    '89848539122007344',
    '89880345515638625',
    '89896204194964448',
    '89969897520284480',
    '90010241312333393',
    '90031501817339552',
    '90037811665186016',
    '90127246523802417',
    '90127326629435841',
    '90135603990132225',
    '90163753341695809',
    '90172844493692480',
    '90173968277693249',
    '90207288890460865',
    '90246427557475376',
    '90252073971668320',
    '90293572470161952',
    '90321398525152736',
    '90327469987102145',
    '90332817802308640',
    '90399158195724752',
    '90473400215028352',
    '90513809810131312',
    '90598738792526944',
    '90599866499311776',
    '90688910073135297',
    '90729048447052800',
    '90791709927640224',
    '90797430150059264',
    '90836502447169952',
    '90840789211604048',
    '90910679553135265',
    '90955553467111249',
    '91005194750034464',
    '91107097130270400',
    '91120121727188609',
    '91250514358592672',
    '91329569249288769',
    '91361847043080400',
    '89329608853128288',
    '89364936821344896',
    '89839796561904929',
    '89958125601566961',
    '89997339418747777',
    '90009609130378257',
    '90059530916627969',
    '90258899387578336',
    '90360966983802448',
    '90576680708221921',
    '90949316113004816',
    '90972311574832433',
    '91080503304847328',
    '91353087352736736',
    '91437504999287200',
    '89222620849510145',
    '91005234554242641',
    '88701724462867649',
    '88786970344150112',
    '89981796966546737',
    '91402887254828368',
    '89409996620502544',
    '91210948485412928',
    '89018361177929809',
    '90724949851032945',
    '90829728879723920',
    '91193135505078640',
    '90019861140866640',
    '89538475013487072',
    '89860038384233984',
    '91210548905645393',
    '89308012820785888',
    '89617667142643760',
    '89607245310211489',
    '90757935350815969',
    '89860541244171121',
    '90892725971526912',
    '90886830738859280',
    '90853461057266320',
    '90806805288251792',
    '90472888904266304',
    '89824038902302577',
    '90135219888606641',
    '91029359883680448',
    '90434994851785744',
    '90333231764534192',
    '90529509422642336',
    '90529639828432736',
    '91357318422536304'
  ];
  var userRequest = [
    '88096698426400385',
    '88096706899774400',
    '88354827595032721',
    '88770059167850369',
    '88770060663799793',
    '88770086312254177',
    '88775479126833601',
    '88810673591548449',
    '88911136544698224',
    '88911143320755648',
    '89018389627510081',
    '89091351154758240',
    '89138464836818065',
    '89183114982564704',
    '89244113023388657',
    '89295369695148528',
    '89301959129114097',
    '89504545841807728',
    '89534114665094448',
    '89606610296086240',
    '89641336900131600',
    '89731870992552785',
    '89738745919815345',
    '89823303352910497',
    '89840086806894128',
    '89845003632280944',
    '89848539122007344',
    '89880345515638625',
    '89896204194964448',
    '89969897520284480',
    '90010241312333393',
    '90031501817339552',
    '90037811665186016',
    '90127246523802417',
    '90127326629435841',
    '90135603990132225',
    '90163753341695809',
    '90172844493692480',
    '90173968277693249',
    '90207288890460865',
    '90246427557475376',
    '90252073971668320',
    '90293572470161952',
    '90321398525152736',
    '90327469987102145',
    '90332817802308640',
    '90399158195724752',
    '90473400215028352',
    '90513809810131312',
    '90598738792526944',
    '90599866499311776',
    '90688910073135297',
    '90729048447052800',
    '90791709927640224',
    '90797430150059264',
    '90836502447169952',
    '90840789211604048',
    '90910679553135265',
    '90955553467111249',
    '91005194750034464',
    '91107097130270400',
    '91120121727188609',
    '91250514358592672',
    '91329569249288769',
    '91361847043080400'
  ];

  isValidRequest(whitelist, userRequest).should.eql(true);
});

Data size has increased(whitelist: 3 -> 114, userRequest: 2 -> 65), and I verified all elements in userRequest are in whitelist. So the test should pass, but failed.

I made a function that works exactly same but implementation is different:

var isValidRequest2 = function (whitelist, userRequest) {
  return _.isArray(userRequest) && _.all(userRequest, function(elem) { return _.contains(whitelist, elem); });
};

With this new function, all tests passed.

In console of Chorme dev tools, same things happen:

> _.all(userRequest, _.curry(_.contains)(whitelist))
  false
> _.all(userRequest, function(elem) { return _.contains(whitelist, elem); })
  true

I think there's some problem with _.curry, but not sure.

It'll be great if someone explain the problem of the first function using _.curry.

FYI, I'm using lodash v2.4.1 .

Upvotes: 0

Views: 432

Answers (1)

phadej
phadej

Reputation: 12133

_.all calls iterator (the second parameter) with additional parameters

_.all([1, 2, 3], function () { console.log(arguments); return true; });
[1, 0, Array[3]]
[2, 1, Array[3]]
[3, 2, Array[3]]
true

_.contains has an optional third parameter, fromIndex, which matches index given by _.all. Thus real data breaks.

Try to reorder elements in your basic tests, and you'll see the fact.

isValidRequest(['a', 'b', 'c'], ['a', 'c']) // true
isValidRequest(['a', 'b', 'c'], ['c', 'a']) // false

Upvotes: 2

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