Remove fields that do not exist in object y

[rendomnet]

Suggestion

How this can be done?

const x = {
  record: {
    prop1: "value1",
    prop2: "value2"
  }
};

const y = {
  record: {
    prop1: "changed"
  }
};

merge(x,y)

//return
{
 record: {
    prop1: "changed"
  }
}

[RebeccaStevens]

I'm not sure how y is supposed to differ from the result but essentially this should do what you want:

import { deepmergeCustom } from "deepmerge-ts";

export const myDeepmerge = deepmergeCustom({
  mergeOthers: (values, utils, meta) => {
    const objectToGetKeysOf = meta.parents[meta.parents.length - 1];
    const keysToKeep = new Set([
      ...Object.keys(objectToGetKeysOf),
      ...Object.getOwnPropertySymbols(objectToGetKeysOf)
    ]);

    if (!keysToKeep.has(meta.key)) {
      return utils.actions.skip;
    }
    return utils.actions.defaultMerge;
  }
});

import { myDeepmerge } from "./path/to/this/function";

const x = {
  record: {
    prop1: "value1",
    prop2: "value2"
  }
};

const y = {
  record: {
    prop1: "changed"
  }
};

const result = myDeepmerge(x, y);

[RebeccaStevens]

Sorry, I'm not exactly sure what you are trying to do. y and return in that code above are the same and it is also what the code I gave will return.

[rendomnet]

Sorry, I'm not exactly sure what you are trying to do. y and return in that code above are the same and it is also what the code I gave will return.

edited.

[rendomnet]

Gives error
Cannot read properties of undefined (reading 'defaultMerge')
https://codesandbox.io/s/nifty-field-2nd9ye?file=/src/example.ts

[fatihaziz]

change it to:

// ... above codes

    if (!keysToKeep.has(meta.key)) {
      return utils.actions?.skip;
    }
    return utils.actions?.defaultMerge;

// ... below codes

so it won't error. there is reason actions being undefined or null

[RebeccaStevens]

@rendomnet Sorry, I forgot about this discussion. This issue with the sandbox you linked is that it is using an older version of deepmerge-ts (v3.0.0). actions were introduced in v4.0.0.