Javascript - Move contents of JSON object one level up recursively

prashant
January 10, 2024
125 views
0 votes
2 Answers

I have particular field – "dataQuery". I want to move the entire content inside this field to one level up and finally delete this key itself. The original JSON is nested and can be upto 3-4MB in size. What are some possible ways to do this ?
As an example the following JSON:

{
  "name": "John",
  "age": 25,
  "value": {
        "dataQuery": {
             "nestedField1": "value1",
             "duplicateKey": "value1",
             "dataQuery": {
                 "nestedField2": "value3",
                 "duplicateKey": "value2"
              }
         },
         "child": [{
                "nestedField3": {
                    "dataQuery": { 
                         "nestedField4": "value4"
                     }
                }
         }] 
    }
}

should be transformed to the following:

{
  "name": "John",
  "age": 25,
  "value": {
             "nestedField1": "value1",
             "nestedField2": "value3",
             "duplicateKey": "value2"
         ,
         "child": [{
                "nestedField3": { 
                     "nestedField4": "value4"
                }
         }] 
    }
}

Tags: javascript json

Answers

How about something like:

let myObj = {
  name: 'John',
  age: 25,
  value: {
dataQuery: {
  nestedField1: 'value1',
  duplicateKey: 'value1',
  dataQuery: {
    nestedField2: 'value3',
    duplicateKey: 'value2',
  },
},
child: [
  {
    nestedField3: {
      dataQuery: {
        nestedField4: 'value4',
      },
    },
  },
],
  },
};

const collapseDataQuery = (obj) => {
  let retVal = {};
  Object.keys(obj).forEach((key) => {
if (key === 'dataQuery' && typeof obj[key] === 'object') {
    retVal = { ...retVal, ...collapseDataQuery(obj[key]) };
} else if (Array.isArray(obj[key])) {
  retVal[key] = obj[key].map((item) => collapseDataQuery(item));
} else if (typeof obj[key] === 'object') {
  retVal[key] = collapseDataQuery(obj[key]);
} else {
  retVal[key] = obj[key];
}
  });
  return retVal;
};

console.log('Before:');
console.log(JSON.stringify(myObj, null, 2));

myObj.value = collapseDataQuery(myObj.value);

console.log('-------------------');
console.log('After:');
console.log(JSON.stringify(myObj, null, 2));

.as-console-wrapper { min-height: 100% !important; }

You could use recursion to iterate through every object/array (obj) and compare the reference key (refKey) to the target key (targetKey).

If your reference key is the target key (targetKey), assign the current object (obj) to the parent (parent) and delete the target key (targetKey) off of the parent (parent).

The recursion is done before the removal occurs (post-order traversal).

const data = {
  "name": "John",
  "age": 25,
  "value": {
    "dataQuery": {
      "nestedField1": "value1",
      "duplicateKey": "value1",
      "dataQuery": {
        "nestedField2": "value3",
        "duplicateKey": "value2"
      }
    },
    "child": [{
      "nestedField3": {
        "dataQuery": {
          "nestedField4": "value4"
        }
      }
    }]
  }
};

const pruneObject = (obj, targetKey, refKey = null, parent = null) => {
  if (typeof obj === 'object') {
    for (let k in obj) { pruneObject(obj[k], targetKey, k, obj); }
  }
  if (refKey === targetKey) {
    Object.assign(parent, obj); // Assign the object to its parent
    delete parent[targetKey]; // Remove the target association
  }
};

pruneObject(data, 'dataQuery'); // Modifies the object in-place
console.log(data); // Display the modified object

.as-console-wrapper { top: 0; max-height: 100% !important; }

Output

{
  "name": "John",
  "age": 25,
  "value": {
    "child": [
      {
        "nestedField3": {
          "nestedField4": "value4"
        }
      }
    ],
    "nestedField1": "value1",
    "duplicateKey": "value2",
    "nestedField2": "value3"
  }
}

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Javascript – Move contents of JSON object one level up recursively

Answers

Output