Truffle .call() returns values with array index instead of keys

Question

I am currently writing tests for solidity contract using truffle. When I invoke a function from the contract with .call(), the object that is being returned to me has the values included twice, once with their keys and a second time with an array index associated with the values.

For example, I would expect my return value to be:

{ 
  name: 'jeff',
  id: '0'
}

Instead, I am receiving:

{ 
  '0': 'jeff',
  '1': 0,
  name: 'jeff',
  id: '0'
}

While the correct data is there, it would make my tests much cleaner if I only received the key value pairs, and not this strange array structure in addition.

How can I prevent truffle from returning these duplicates?

Answer 1

How can I prevent truffle from returning these duplicates?

It is web3.js code which is responsible for these duplicated values.

You can see here an example from the official documentation.

The reason, as stated in the example linked above, is to allow you to obtain these values even if the keys are not known.

An example for when the keys are known to web3.js:

function func(uint x) public returns (uint y, uint z)

An example for when the keys are not known to web3.js:

function func(uint x) public returns (uint, uint)

In order to get rid of these duplicated values, you can open web3.js source file (under node_modules) and fix the code manually. However, I would advise against it, because you can simply ignore that redundant piece of information in your own code.