How to effectively filter tree view retaining its existing structure?

Question

I am having a tree structured JSON which should be filtered and the result should retain the tree structure.

var tree = [
  {
    text: "Parent 1",
    nodes: [
      {
        text: "Child 1",
        type: "Child",
        nodes: [
          {
            text: "Grandchild 1"
            type: "Grandchild"
          },
          {
            text: "Grandchild 2"
            type: "Grandchild"
          }
        ]
      },
      {
        text: "Child 2",
        type: "Child"
      }
    ]
  },
  {
    text: "Parent 2",
    type: "Parent"
  },
  {
    text: "Parent 3",
    type: "Parent"
  }
];

Example :

1)If search query is Parent 1

Expected result :

[
  {
    text: "Parent 1",
    nodes: [
      {
        text: "Child 1",
        type: "Child",
        nodes: [
          {
            text: "Grandchild 1"
            type: "Grandchild"
          },
          {
            text: "Grandchild 2"
            type: "Grandchild"
          }
        ]
      },
      {
        text: "Child 2",
        type: "Child"
      }
    ]
  }
]

2)If search query is Child 1

Expected result :

[
  {
    text: "Parent 1",
    nodes: [
      {
        text: "Child 1",
        type: "Child",
        nodes: [
          {
            text: "Grandchild 1"
            type: "Grandchild"
          },
          {
            text: "Grandchild 2"
            type: "Grandchild"
          }
        ]
      }
    ]
  }
]

3)If search query is Grandchild 2

Expected result :

[
  {
    text: "Parent 1",
    nodes: [
      {
        text: "Child 1",
        type: "Child",
        nodes: [
          {
            text: "Grandchild 2"
            type: "Grandchild"
          }
        ]
      }
    ]
  }
]

I need to retain the tree structure based on the node level (type here). So far I have tried filtering recursively but couldn't re-map the results.

angular.module("myApp",[])
   .filter("filterTree",function(){
       return function(items,id){
          var filtered = [];
          var recursiveFilter = function(items,id){
              angular.forEach(items,function(item){
                 if(item.text.toLowerCase().indexOf(id)!=-1){
                    filtered.push(item);
                 }
                 if(angular.isArray(item.items) && item.items.length > 0){
                    recursiveFilter(item.items,id);              
                 }
              });
          };
          recursiveFilter(items,id);
          return filtered;
       }; 
    });
});

My JSON is pretty large and hence remapping based on types are expected to be done in the filter itself. Please advice.

Answer 1

You could use a nested recursive approach and filter the tree, while respecting the found item.

This solution does not mutate the original data.

function filter(array, text) {
    const getNodes = (result, object) => {
        if (object.text === text) {
            result.push(object);
            return result;
        }
        if (Array.isArray(object.nodes)) {
            const nodes = object.nodes.reduce(getNodes, []);
            if (nodes.length) result.push({ ...object, nodes });
        }
        return result;
    };

    return array.reduce(getNodes, []);
}

var tree = [{ text: "Parent 1", nodes: [{ text: "Child 1", type: "Child", nodes: [{ text: "Grandchild 1", type: "Grandchild" }, { text: "Grandchild 2", type: "Grandchild" }] }, { text: "Child 2", type: "Child" }] }, { text: "Parent 2", type: "Parent" }, { text: "Parent 3", type: "Parent" }];

console.log(filter(tree, 'Parent 1'));
console.log(filter(tree, 'Child 1'));
console.log(filter(tree, 'Grandchild 2'));

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