Best way to flatten JSON data

Question

I have JSON data as below:

    "Positions": [
            {
              "CRVL_CMB_AMT": 0,
              "CRVL_PERUT_CMB_AMT": null,
              "ISS_ID": "USD",
              "LOCAL_CURR_CDE": "USD",
              "QUANTITY": -4739568084,
              "UT_PRC_CMB_AMT": 100,
              "VALVAL_CMB_AMT": -4739568084,
              "VALVAL_ALT_CMB_AMT": -4739568084,
              "Instrument": {
                "ISS_NME": "US DOLLAR",
                "ISS_TYP": "CASH",
                "ASSET_CLASS_MNEM": "BALANCE"
              }
            },
            {
              "CRVL_CMB_AMT": 0,
              "CRVL_PERUT_CMB_AMT": null,
              "ISS_ID": "REPO-USD-WF",
              "LOCAL_CURR_CDE": "USD",
              "QUANTITY": -770000,
              "UT_PRC_CMB_AMT": 100,
              "VALVAL_CMB_AMT": -770122,
              "VALVAL_ALT_CMB_AMT": -770122,
              "Instrument": {
                "ISS_NME": "REPURCHASE AGREEMENT -  USD WF",
                "ISS_TYP": "REPO",
                "ASSET_CLASS_MNEM": "CURR EQUIV"
              }
            },
            {
              "CRVL_CMB_AMT": 0,
              "CRVL_PERUT_CMB_AMT": null,
              "ISS_ID": "REPO-USD-GS",
              "LOCAL_CURR_CDE": "USD",
              "QUANTITY": -770000,
              "UT_PRC_CMB_AMT": 100,
              "VALVAL_CMB_AMT": -770122,
              "VALVAL_ALT_CMB_AMT": -770122,
              "Instrument": {
                "ISS_NME": "REPURCHASE AGREEMENT -  USD GS",
                "ISS_TYP": "REPO",
                "ASSET_CLASS_MNEM": "CURR EQUIV"
              }
            }
]

I would like to convert this JSON to :

    [{
              "CRVL_CMB_AMT": 0,
              "CRVL_PERUT_CMB_AMT": null,
              "ISS_ID": "USD",
              "LOCAL_CURR_CDE": "USD",
              "QUANTITY": -4739568084,
              "UT_PRC_CMB_AMT": 100,
              "VALVAL_CMB_AMT": -4739568084,
              "VALVAL_ALT_CMB_AMT": -4739568084,          
              "ISS_NME": "US DOLLAR",
              "ISS_TYP": "CASH",
              "ASSET_CLASS_MNEM": "BALANCE"              
            },
{
                  "CRVL_CMB_AMT": 0,
                  "CRVL_PERUT_CMB_AMT": null,
                  "ISS_ID": "REPO-USD-WF",
                  "LOCAL_CURR_CDE": "USD",
                  "QUANTITY": -770000,
                  "UT_PRC_CMB_AMT": 100,
                  "VALVAL_CMB_AMT": -770122,
                  "VALVAL_ALT_CMB_AMT": -770122,
                    "ISS_NME": "REPURCHASE AGREEMENT -  USD WF",
                    "ISS_TYP": "REPO",
                    "ASSET_CLASS_MNEM": "CURR EQUIV"
                },
                {
                  "CRVL_CMB_AMT": 0,
                  "CRVL_PERUT_CMB_AMT": null,
                  "ISS_ID": "REPO-USD-GS",
                  "LOCAL_CURR_CDE": "USD",
                  "QUANTITY": -770000,
                  "UT_PRC_CMB_AMT": 100,
                  "VALVAL_CMB_AMT": -770122,
                  "VALVAL_ALT_CMB_AMT": -770122,
                    "ISS_NME": "REPURCHASE AGREEMENT -  USD GS",
                    "ISS_TYP": "REPO",
                    "ASSET_CLASS_MNEM": "CURR EQUIV"
                }]

Is there any efficient way to flatten this. Length of array can be very large in 10 thousands.

Thanks

don't understood what you mean flatten here. if you want to create array from Position then you can ```[...obj.Positions]``` — Dipak Telangre, May 11 '20 at 06:54
Each element of positions array have key Like Instruments which is object itself Since I want to use this in Grid, I need to get the key value from inside Intruments at the same level. — Amit, May 11 '20 at 06:59
Does this answer your question? [Keeping only certain properties in a JavaScript object](https://stackoverflow.com/questions/22202766/keeping-only-certain-properties-in-a-javascript-object) — Shlok Nangia, May 11 '20 at 07:01

Jack Bashford · Accepted Answer · 2020-05-11T07:07:03.863

If it's a static key, just extract Instrument and spread it to the object:

const data = {"Positions":[{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"USD","LOCAL_CURR_CDE":"USD","QUANTITY":-4739568084,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-4739568084,"VALVAL_ALT_CMB_AMT":-4739568084,"Instrument":{"ISS_NME":"US DOLLAR","ISS_TYP":"CASH","ASSET_CLASS_MNEM":"BALANCE"}},{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"REPO-USD-WF","LOCAL_CURR_CDE":"USD","QUANTITY":-770000,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-770122,"VALVAL_ALT_CMB_AMT":-770122,"Instrument":{"ISS_NME":"REPURCHASE AGREEMENT -  USD WF","ISS_TYP":"REPO","ASSET_CLASS_MNEM":"CURR EQUIV"}},{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"REPO-USD-GS","LOCAL_CURR_CDE":"USD","QUANTITY":-770000,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-770122,"VALVAL_ALT_CMB_AMT":-770122,"Instrument":{"ISS_NME":"REPURCHASE AGREEMENT -  USD GS","ISS_TYP":"REPO","ASSET_CLASS_MNEM":"CURR EQUIV"}}]};

const res = Object.values(data)[0].map(({ Instrument, ...o }) => ({ ...Instrument, ...o }));

console.log(res);

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To do this dynamically and detect which items are objects, you'd need to iterate through each property:

const data = {"Positions":[{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"USD","LOCAL_CURR_CDE":"USD","QUANTITY":-4739568084,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-4739568084,"VALVAL_ALT_CMB_AMT":-4739568084,"Instrument":{"ISS_NME":"US DOLLAR","ISS_TYP":"CASH","ASSET_CLASS_MNEM":"BALANCE"}},{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"REPO-USD-WF","LOCAL_CURR_CDE":"USD","QUANTITY":-770000,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-770122,"VALVAL_ALT_CMB_AMT":-770122,"Instrument":{"ISS_NME":"REPURCHASE AGREEMENT -  USD WF","ISS_TYP":"REPO","ASSET_CLASS_MNEM":"CURR EQUIV"}},{"CRVL_CMB_AMT":0,"CRVL_PERUT_CMB_AMT":null,"ISS_ID":"REPO-USD-GS","LOCAL_CURR_CDE":"USD","QUANTITY":-770000,"UT_PRC_CMB_AMT":100,"VALVAL_CMB_AMT":-770122,"VALVAL_ALT_CMB_AMT":-770122,"Instrument":{"ISS_NME":"REPURCHASE AGREEMENT -  USD GS","ISS_TYP":"REPO","ASSET_CLASS_MNEM":"CURR EQUIV"}}]};

const res = Object.values(data)[0].map(e => {
  Object.entries(e).forEach(([k, v]) => {
    if (v && typeof v == "object" && !v.map) {
      e = { ...e, ...v };
      delete e[k];
    }
  });
  return e;
});

console.log(res);

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The above will work for any nested object at a single depth.

I can have multiple key like intruments. Such as accounts, Issue. — Amit, May 11 '20 at 07:04
Fixed @Amit, check the bottom one. That should fix your problem. — Jack Bashford, May 11 '20 at 07:07
I tried your solution bit in different way. It worked. Thanks a lot — Amit, May 11 '20 at 11:39

Best way to flatten JSON data

1 Answers1