feat: Add obj._array2tree and obj._tree2array helper methods

src/helper/obj.js

@@ -74,9 +74,71 @@ function _deep_clone(obj) {
   return copy;
 }
 
+function _array2tree(data, options = {}) {
+  if (!is.array(data)) {
+    throw new Error('data must be an array');
+  }
+  const c = _assign({
+    parent_index: 'parent_id',
+    data_index: 'id',
+    child_name: 'child'
+  }, options);
+
+  const items = [];
+  data.forEach(d => {
+    if (typeof d[c.child_name] === 'undefined') {
+      d[c.child_name] = [];
+    } else {
+      throw new Error('child name "' + c.child_name + '" is reserved for child data, please use another name');
+    }
+    items[d[c.data_index]] = d;
+    if (typeof d[c.parent_index] === 'undefined' || typeof d[c.data_index] === 'undefined') {
+      throw new Error('data must have "' + c.parent_index + '" and "' + c.data_index + '"');
+    }
+  });
+
+  const tree = [];
+  let n = 0;
+  data.forEach(item => {
+    if (items[item[c.parent_index]]) {
+      items[item[c.parent_index]][c.child_name].push(items[item[c.data_index]]);
+    } else {
+      tree[n++] = items[item[c.data_index]];
+    }
+  });
+  return tree;
+}
+
+function _tree2array(tree, options = {}) {
+  if (!is.array(tree)) {
+    tree = [tree];
+  }
+  const c = _assign({
+    parent_index: 'parent_id',
+    data_index: 'id',
+    child_name: 'child'
+  }, options);
+  const res = [];
+  function recurse(data, parent_id) {
+    data.forEach(d => {
+      const child = d[c.child_name].map(i => i);
+      delete d[c.child_name];
+      d[c.parent_index] = parent_id || 0;
+      res.push(d);
+      if (child.length) {
+        recurse(child, d[c.data_index]);
+      }
+    });
+  }
+  recurse(tree, 0);
+  return res;
+}
+
 module.exports = {
   _assign,
   _flatten,
   _unflatten,
+  _array2tree,
+  _tree2array,
   _deep_clone
 };

tests/obj.tests.js

@@ -2,7 +2,7 @@
 
 const expect = require('chai').expect;
 const { Configuration } = require('..');
-const { _deep_clone, _flatten, _unflatten } = require('../src/helper/obj');
+const { _deep_clone, _flatten, _unflatten, _array2tree, _tree2array } = require('../src/helper/obj');
 
 describe('obj test case', function () {
   it('flatten', function () {
@@ -66,4 +66,68 @@ describe('obj test case', function () {
     expect(complexObj.a.b.c.d.length).to.be.equal(1);
     expect(complexObj.a.b.c.d[0].x).to.be.equal('1');
   });
+  it('array2tree', function () {
+    const data = [
+      { id: 1, parent_id: 0 },
+      { id: 2, parent_id: 3 },
+      { id: 3, parent_id: 1 },
+      { id: 4, parent_id: 2 },
+      { id: 5, parent_id: 6 },
+      { id: 6, parent_id: 7 },
+      { id: 7, parent_id: 5 }
+    ];
+    const res = _array2tree(data, { parent_index: 'parent_id', data_index: 'id', child_name: 'child' });
+    expect(res.length).to.be.equal(1);
+    expect(res[0].id).to.be.equal(1);
+    expect(res[0].child.length).to.be.equal(1);
+    expect(res[0].child[0].id).to.be.equal(3);
+    expect(res[0].child[0].child.length).to.be.equal(1);
+    expect(res[0].child[0].child[0].id).to.be.equal(2);
+    expect(res[0].child[0].child[0].child.length).to.be.equal(1);
+    expect(res[0].child[0].child[0].child[0].id).to.be.equal(4);
+    expect(res[0].child[0].child[0].child[0].child.length).to.be.equal(0);
+    expect(res[0].child[0].child[0].child[0].parent_id).to.be.equal(2);
+
+    // throw error when data is not array
+    expect(() => _array2tree(null)).to.throw('data must be an array');
+    expect(() => _array2tree([{ id: 1 }])).to.throw('data must have "parent_id" and "id"');
+    expect(() => _array2tree([{ id: 1, parent_id: 0, child: [] }])).to.throw('child name "child" is reserved for child data, please use another name');
+  });
+
+  it('tree2array', function () {
+    const data = [
+      {
+        'id': 1,
+        'parent_id': 0,
+        'child': [
+          {
+            'id': 3,
+            'parent_id': 1,
+            'child': [
+              {
+                'id': 2,
+                'parent_id': 3,
+                'child': [
+                  {
+                    'id': 4,
+                    'parent_id': 2,
+                    'child': []
+                  }
+                ]
+              }
+            ]
+          }
+        ]
+      }
+    ];
+    let res = _tree2array(data, { parent_index: 'parent_id', data_index: 'id', child_name: 'child' });
+    expect(JSON.stringify(_array2tree(res))).to.equal(JSON.stringify(data));
+
+    const data2 = _deep_clone(data);
+    delete data2[0].parent_id;
+    delete data2[0].child[0].parent_id;
+    delete data2[0].child[0].child[0].parent_id;
+    res = _tree2array(data2[0]);
+    expect(JSON.stringify(_array2tree(res))).to.equal(JSON.stringify(data));
+  });
 });