How to map over an array and use index such that empty values are eliminated?

Question

I have two arrays keyVals and rows defined as below:

    keyVals = 
    [
      "Status",
      "ErrorHeading",
      "ErrorDetail"
    ]
    
rows =
[
  {
    "Hostname": "ABC",
    "name": "Check1",
    "Status": "PASS",
    "ErrorHeading": "",
    "ErrorDetail": ""
  },
  {
    "Hostname": "ABC",
    "name": "Check2",
    "Status": "PASS",
    "ErrorHeading": "",
    "ErrorDetail": ""
  },
  {
    "Hostname": "ABC",
    "name": "Check3",
    "Status": "FAIL",
    "ErrorHeading": "Heading3",
    "ErrorDetail": "ErrorDetails3"
  }
]

I have written the following code to generate a Res:

function dArray(rows, keyVals) {
    const response = Object.values(rows.reduce((res, {Hostname, name, ...o}) => {
        res[Hostname] = res[Hostname] || {Hostname};
        keyVals.forEach(kv => res[Hostname][name + kv] = o[kv]);
        return res;
    }, {}));
    return response;
}

const Res = dArray(rows, keyVals);

The Res values looks as below:

Res = 
[
  {
    "Hostname": "ABC",
    "Check1kStatus": "PASS",
    "Check1ErrorHeading": "",
    "Check1ErrorDetail": "",
    "Check2Status": "PASS",
    "Check2ErrorHeading": "",
    "Check2ErrorDetail": "",
    "Check3Status": "FAIL",
    "Check3ErrorHeading": "Heading3",
    "Check3ErrorDetail": "ErrorDetails3"
  }
]

I want to modify function dArray(rows, keyVals) such that the Res excludes all empty values as below:

Res = 
[
  {
    "Hostname": "ABC",
    "Check1kStatus": "PASS",
    "Check2Status": "PASS",
    "Check3Status": "FAIL",
    "Check3ErrorHeading": "Heading3",
    "Check3ErrorDetail": "ErrorDetails3"
  }
]

There's no such thing as a "JSON Object"

Andreas
– Andreas

2020-06-24 16:48:29 +00:00
Commented Jun 24, 2020 at 16:48 — Andreas
– Andreas, Commented Jun 24, 2020 at 16:48
keyVals and rows are arrays

Andreas
– Andreas

2020-06-24 16:48:39 +00:00
Commented Jun 24, 2020 at 16:48 — Andreas
– Andreas, Commented Jun 24, 2020 at 16:48
And the problem is? if (o[kv]) { ... }

Andreas
– Andreas

2020-06-24 16:51:44 +00:00
Commented Jun 24, 2020 at 16:51 — Andreas
– Andreas, Commented Jun 24, 2020 at 16:51

lightBullet · Accepted Answer · 2020-06-24 17:12:34Z

1

function dArray(rows, keyVals) {
    const response = Object.values(rows.reduce((res, {Hostname, name, ...o}) => {
        res[Hostname] = res[Hostname] || {Hostname};
        keyVals.forEach(kv => (o[kv] && (res[Hostname][name + kv] = o[kv])));
        return res;
    }, {}));
    return response;
}

answered Jun 24, 2020 at 17:12

lightBullet

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Comments

richytong · Accepted Answer · 2020-06-24 16:59:45Z

You can do it with a special filterObject function.

const keyVals = ["Status", "ErrorHeading", "ErrorDetail"]
    
const rows = [
  { "Hostname": "ABC", "name": "Check1", "Status": "PASS", "ErrorHeading": "", "ErrorDetail": "" },
  { "Hostname": "ABC", "name": "Check2", "Status": "PASS", "ErrorHeading": "", "ErrorDetail": "" },
  { "Hostname": "ABC", "name": "Check3", "Status": "FAIL", "ErrorHeading": "Heading3", "ErrorDetail": "ErrorDetails3" },
]

const filterObject = (fn, x) => {
  const y = {}
  for (const k in x) {
    const ok = fn(x[k])
    if (ok) { y[k] = x[k] }
  }
  return y
}

function dArray(rows, keyVals) {
    const response = Object.values(rows.reduce((res, {Hostname, name, ...o}) => {
        res[Hostname] = res[Hostname] || {Hostname};
        keyVals.forEach(kv => res[Hostname][name + kv] = o[kv]);
        return res;
    }, {}));
    return response.map(obj => filterObject(x => x !== '', obj))
}

const Res = dArray(rows, keyVals);

console.log(Res)

filterObject is adapted from the polymorphic filter from my functional programming library, rubico. Docs for filter here, if you are interested.

luek baja · Accepted Answer · 2020-06-24 17:02:01Z

1

function dArray(rows, keyVals) {
  const response = Object.values(rows.reduce((res, {Hostname, name}) => {
      res[Hostname] = res[Hostname] || {Hostname};
      keyVals.forEach(kv => res[Hostname][name + kv] = o[kv]);
      return res;
  }, {}));

  let keys=Object.keys(response[0]);
  for(let i=0,l=keys.length;i<l;i++){
    if(!response[0][keys[i]]){
      delete response[0][keys[i]];
    }  
  }

  return response;
}

edited Jun 24, 2020 at 17:02

answered Jun 24, 2020 at 16:52

luek baja

1,71215 silver badges32 bronze badges

1 Comment

meallhour Over a year ago

Is there a way I can update function dArray(rows, keyVals) instead of creating another function?

Siva Kondapi Venkata · Accepted Answer · 2020-06-24 17:22:11Z

Before returning response, use map and Object.entries to filter empty values in object.

function dArray(rows, keyVals) {
  const response = Object.values(
    rows.reduce((res, { Hostname, name, ...o }) => {
      res[Hostname] = res[Hostname] || { Hostname };
      keyVals.forEach((kv) => (res[Hostname][name + kv] = o[kv]));
      return res;
    }, {})
  );
  return response.map((obj) =>
    Object.fromEntries(Object.entries(obj).filter(([, val]) => val))
  );
}

keyVals = ["Status", "ErrorHeading", "ErrorDetail"];

rows = [
  {
    Hostname: "ABC",
    name: "Check1",
    Status: "PASS",
    ErrorHeading: "",
    ErrorDetail: "",
  },
  {
    Hostname: "ABC",
    name: "Check2",
    Status: "PASS",
    ErrorHeading: "",
    ErrorDetail: "",
  },
  {
    Hostname: "ABC",
    name: "Check3",
    Status: "FAIL",
    ErrorHeading: "Heading3",
    ErrorDetail: "ErrorDetails3",
  },
];

console.log(dArray(rows, keyVals));

Cat · Accepted Answer · 2020-06-24 17:42:37Z

This does it by filtering the output of your Object.values() call.

const
  keyVals = [ "Status", "ErrorHeading", "ErrorDetail" ],
  rows = getRows();

function dArray(rows, keyVals) {
  const reducedValues = Object.values(
    rows.reduce( (res, { Hostname, name, ...o }) => {
      res[Hostname] = res[Hostname] || { Hostname };
      keyVals.forEach(kv => res[Hostname][name + kv] = o[kv]);
      return res;
    }, {})
  ),
  response = [
    Object.fromEntries(
      Object.entries(reducedValues[0]).filter(en=>en[1])
    )
  ];
  return response;
}
const Res = dArray(rows, keyVals);
console.log(Res);


function getRows(){
  return [{
      "Hostname": "ABC",
      "name": "Check1",
      "Status": "PASS",
      "ErrorHeading": "",
      "ErrorDetail": ""
    },
    {
      "Hostname": "ABC",
      "name": "Check2",
      "Status": "PASS",
      "ErrorHeading": "",
      "ErrorDetail": ""
    },
    {
      "Hostname": "ABC",
      "name": "Check3",
      "Status": "FAIL",
      "ErrorHeading": "Heading3",
      "ErrorDetail": "ErrorDetails3"
    }
  ];
}

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