将对象数组渲染为树

Question

I have an array of objects in which each element contains a string representing its position in a tree structure. What would be a simple way to generate a tree view (using basic ul / li tags for example) based on that data?

The depth of the tree structure isn't known beforehand so probably recursion would be the solution?

I'm using React but I guess the question isn't really React-specific so generic JS or even pseudo-code would help a lot.

Example data:

[
    {
        "name":  "banana",
        "path": "food.healthy.fruit",
        // ... may contain other parameters
    },
    {
        "name":  "apple",
        "path": "food.healthy.fruit"
    }
    {
        "name":  "carrot",
        "path": "food.healthy.vegetable"
    },
    {
        "name":  "bread",
        "path": "food"
    },
    {
        "name":  "burger"
        "path": "food.unhealthy"
    },
    {
        "name":  "hotdog"
        "path": "food.unhealthy"
    },
    {
        "name": "germany",
        "path": "country.europe"
    },
    {
        "name": "china",
        "path": "country.asia"
    }
]

Desired result:

<ul>
    <li>
    food
    <ul>
        <li>bread</li>
        <li>healthy
        <ul>
            <li>
            fruit
            <ul>
                <li>apple</li>
                <li>banana</li>
            </ul>
            </li>
            <li>
            vegetable
            <ul>
                <li>carrot</li>
            </ul>
            </li>
        </ul>
        </li>
        <li>
        unhealthy
        <ul>
            <li>burger</li>
            <li>hotdog</li>
        </ul>
        </li>
    </ul>
    </li>
    <li>
    country
    <ul>
        <li>
        europe
        <ul>
            <li>germany</li>
        </ul>
        </li>
        <li>
        asia
        <ul>
            <li>china</li>
        </ul>
        </li>
    </ul>
    </li>
</ul>

• food
  • bread
  • healthy
    • fruit
      • apple
      • banana
    • vegetable
      • carrot
  • unhealthy
    • burger
    • hotdog
• country
  • europe
    • germany
  • asia
    • china

Answer 1

Group by path at first.

You can do this by iterating through the source data and split path for each item by dot symbol. Then store each item in a object by keys like this

store[country] = store[country] || {}
store[country][europe] = store[country][europe] || []
store[country][europe].push(germany)

Then get all the keys of object at root level and recursivly render all of the items. Here is some pseudo-code:

function render(store){

    let keys = Object.keys(store)

    let ul = document.createElement('ul')

    for (var i = 0; i < keys.length; i++){

      let key = keys[i]

      if (typeof store[key] === 'object') {

        let li = document.createElement('li')

        //create a branch, return it with our render function and append to current level
        li.appendChild(render(store[key]))

      } else {

         // create html presentation for all items under the current key

         let li = document.createElement('li')

      }

       ul.appendChild(li)

    } 

    return ul

}

Answer 2

First of all, you need to restructure data into nested groups. Here is how you can reduce your array to necessary structure:

const tree = data.reduce(function(prev, curr) {
  const branches = curr.path.split('.')
  let branch = prev
  let branchName

  while (branches.length) {
    branchName = branches.shift()
    let rootIndex = branch.length ? branch.findIndex(el => el.name === branchName) : -1

    if (rootIndex === -1) {
      let newBranch = {
        name: branchName,
        children: []
      }
      branch = branch[branch.push(newBranch) - 1].children
    } else {
      branch = branch[rootIndex].children
    }

    if (branches.length === 0) {
      branch.push({
        name: curr.name
      })
    }
  }

  return prev
}, [])

It will give you array similar to this:

[
  {
    name: 'food',
    children: [
      {
        name: 'bread'
      },
      {
        name: 'healthy',
        children: [
          {
            name: 'fruit',
            children: [
              {name: 'bannana'},
              {name: 'apple'}
            ]
          }
        ]
      }
    ]
  },
  {
    name: 'country',
    children: [
      // ...
    ]
  }
]

After that, it's easy to create Tree component that would recursively render branches:

const Tree = (props) => (
  <ul>
    {props.data.map((branch, index) => (
      <li key={index}>
        {branch.name}
        {branch.children && (
          <Tree data={branch.children} />  
        )}
      </li>
    ))}
  </ul>  
)

Demo . Check the demo below.

 const data = [{ "name": "banana", "path": "food.healthy.fruit" }, { "name": "apple", "path": "food.healthy.fruit" }, { "name": "carrot", "path": "food.healthy.vegetable" }, { "name": "bread", "path": "food" }, { "name": "burger", "path": "food.unhealthy" }, { "name": "hotdog", "path": "food.unhealthy" }, { "name": "germany", "path": "country.europe" }, { "name": "china", "path": "country.asia" }] const tree = data.reduce(function(prev, curr) { const branches = curr.path.split('.') let branch = prev let branchName while (branches.length) { branchName = branches.shift() let rootIndex = branch.length ? branch.findIndex(el => el.name === branchName) : -1 if (rootIndex === -1) { let newBranch = { name: branchName, children: [] } branch = branch[branch.push(newBranch) - 1].children } else { branch = branch[rootIndex].children } if (branches.length === 0) { branch.push({ name: curr.name }) } } return prev }, []) const Tree = (props) => ( <ul> {props.data.map((branch, index) => ( <li key={index}> {branch.name} {branch.children && ( <Tree data={branch.children} /> )} </li> ))} </ul> ) ReactDOM.render( <Tree data={tree} />, document.getElementById('demo') ); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> <div id="demo"></div>