Filtering array of objects and nested objects

Question

I have an array of objects that looks like this:

  var data = [
  {
    type: "parent",
    children: [
      {
        type: "parent",
        children: [
            {
              type: "parent"
            },
            {
              type: "parent",
              children: [
                {
                 type: "notParent"
                },
                {
                 type: "parent"
                }
              ]
            }
        ]
      }
    ]
  },
  {
    type: "parent",
    children: [
      {
        type: "parent"
      }
    ]
  },
  {
    type: "parent",
    children: [
      {
        type: "parent",
        children: [
          {
            type: "parent"
          },
          {
            type: "parent"
          }
        ]
      },
      {
        type: "notParent"
      }
    ]
  },
  {
    type: "notParent"
  }
]

This data is an array of objects, and can have objects deeply nested. What I want to do is to create a new array that only contains the objects with the type: "parent" and remove all others. I am finding it hard to make this work for deeply nested objects. I have tried many variations of the following:

        var findAllParents = function(obj, type) {
            if(obj.type === type) { return obj; }
            for(var i in obj) {
                if(obj.hasOwnProperty(i)){
                    var foundParents = findAllParents(obj[i], type);
                    if(foundParents) { return foundParents; }
                }
            }
            return null;
        };

I would like for this to return data like this:

  var data = [
  {
    type: "parent",
    children: [
      {
        type: "parent",
        children: [
            {
              type: "parent"
            },
            {
              type: "parent",
              children: [
                {
                 type: "parent"
                }
              ]
            }
        ]
      }
    ]
  },
  {
    type: "parent",
    children: [
      {
        type: "parent"
      }
    ]
  },
  {
    type: "parent",
    children: [
      {
        type: "parent",
        children: [
          {
            type: "parent"
          },
          {
            type: "parent"
          }
        ]
      }
    ]
  }
]

Only to return all objects with type: "parent"

You want it to 1D array of still nested. Please add expected output. — Maheer Ali
– Maheer Ali, Commented May 6, 2019 at 14:54
@Variable no errors, just the wrong output - repl.it/repls/RoastedSolidFlash — Mandalina
– Mandalina, Commented May 6, 2019 at 15:19

idmitrov · Accepted Answer · 2019-05-06 16:43:47Z

1

const data = [
    {
        type: "parent",
        children: [
            {
                type: "parent",
                children: [
                    {
                        type: "parent"
                    },
                    {
                        type: "parent",
                        children: [
                            {
                                type: "notParent",
                                children: [
                                    {
                                        type: "parent"
                                    }
                                ]
                            },
                            {
                                type: "parent"
                            }
                        ]
                    }
                ]
            }
        ]
    },
    {
        type: "parent",
        children: [
            {
                type: "parent"
            }
        ]
    },
    {
        type: "parent",
        children: [
            {
                type: "parent",
                children: [
                    {
                        type: "parent",
                        children: [
                            {
                                type: "parent",
                                children: [
                                    {
                                        type: "notParent"
                                    }
                                ]
                            }
                        ]
                    },
                    {
                        type: "parent"
                    }
                ]
            },
            {
                type: "notParent"
            }
        ]
    },
    {
        type: "notParent"
    }
];

const filterCollectionItemsOfType = (collection, expectedType = 'parent') => {
    const filteredCollection = collection.filter((item) => item.type === expectedType);

    filteredCollection.forEach((item) => {
        if (item.children && item.children.length) {
            item.children = filterCollectionItemsOfType(item.children, expectedType);
        }
    });

    return filteredCollection;
}

const parentsCollection = filterCollectionItemsOfType(data);

console.log(parentsCollection);

edited May 6, 2019 at 16:43

answered May 6, 2019 at 15:18

idmitrov

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6 Comments

idmitrov Over a year ago

I've corrected the snippet, could you try your scenarios again?

Mandalina Over a year ago

Thank you so much! I was wondering if there is a way to expand your answer to work for data that is even more nested repl.it/repls/NaturalRewardingBusinesssoftware

idmitrov Over a year ago

You can remove the type check and just check if (item.children) the call the recursion again, the type check would be useful only if you want to get the children of a specific type

idmitrov Over a year ago

Could you help me to figure out the difference between the output and the expected output ? Far as I see it works with the data from repl.it/repls/NaturalRewardingBusinesssoftware

Mandalina Over a year ago

I updated the data in repl.it/repls/NaturalRewardingBusinesssoftware the code doesn't work for objects deeply nested

|

Maheer Ali · Accepted Answer · 2019-05-06 15:02:41Z

0

You can make a copy of the data and then apply the recursive function which will remove the desired elements from the children array of each object using filter()

var data = [ { type: "parent", children: [ { type: "parent", children: [ { type: "parent" }, { type: "parent" } ] } ] }, { type: "parent", children: [ { type: "parent" } ] }, { type: "parent", children: [ { type: "parent", children: [ { type: "parent" }, { type: "parent" } ] }, { type: "notParent" } ] } ]

function remove(obj){
  if(obj.children){
    obj.children = obj.children.filter(x => x.type === "parent");
    obj.children.forEach(x => remove(x))
  }
}

let copy = JSON.parse(JSON.stringify(data));

copy.forEach(x => remove(x));

console.log(copy)

answered May 6, 2019 at 15:02

Maheer Ali

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1 Comment

Mandalina Over a year ago

thank you so much for answering! Im so sorry, I should have given a better example, I have updated my question with a more accurate example of the data I need to modify. Some of the objects I need to check will be further nested, and some of them will be at the top level, so obj.children.filter won't work

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