array unique merge

[Nikita Pilgrim]

object-merge-advanced

I need to merge objects, but they can contain arrays with the same objects inside. I need to merge an array into 1, but only unique objects. Can I do this with your library?

const data1 = {
    [year]: {
        [month]: {
            [day]: [message],
        },
    },
};
                    
const _data2 = {
    [year]: {
        [month]: {
            [day]: [message],
        },
    },
};

[Roy Revelt]

hi!

When arrays of plain objects are merged, only unique-ones are kept — this comes out of the box — see https://stackblitz.com/edit/js-shkm7d?file=index.js

Now, if this doesn't suit, you can override the merging algorithm via opts.cb.

mergeAdvanced(
  {
    ...
  },
  {
    ...
  },
  {
    cb: (inputArg1, inputArg2, resultAboutToBeReturned, infoObj) => {
      // whatever you return here gets written as the value of clashing keys:
      return resultAboutToBeReturned
    },
  },
)

You can also use the infoObj, evaluate paths by regex'ing them and conditionally merging only "special" cases, arrays of objects.

General plan would be:

1. in the callback function, isolate the paths that need special merging, use IF-ELSE, on ELSE return resultAboutToBeReturned .
2. if we need to produce an array of unique plain objects, that's array.reduce, and evaluation would be, I suppose lodash.isequal or fast-deep-equal libraries (something that can compare objects by values, as opposed to comparing objects themselves via ===)

If you get stuck, post here more realistic sample inputs + the desired result — I'll help to write a callback function.

Good luck!