Implement ability to specify custom properties

Author: Philipp Alferov

index.js

@@ -1,7 +1,7 @@
 'use strict';
 var util = require('util');
 
-function createTree(list, rootNodes) {
+function createTree(list, rootNodes, customID) {
   var tree = [];
 
   for (var prop in rootNodes) {
@@ -10,9 +10,10 @@ function createTree(list, rootNodes) {
     }
 
     var node = rootNodes[prop];
+    var listItem = list[node[customID]];
 
-    if (list[node.id]) {
-      node.children = createTree(list, list[node.id]);
+    if (listItem) {
+      node.children = createTree(list, listItem, customID);
     }
 
     tree.push(node);
@@ -21,11 +22,12 @@ function createTree(list, rootNodes) {
   return tree;
 }
 
-function orderByParents(list) {
+function orderByParents(list, config) {
   var parents = {};
+  var parentProperty = config.parentProperty;
 
   list.forEach(function(item) {
-    var parentID = item.parent_id || 0;
+    var parentID = item[parentProperty] || 0;
     parents[parentID] = parents[parentID] || [];
     parents[parentID].push(item);
   });
@@ -34,14 +36,19 @@ function orderByParents(list) {
 }
 
 module.exports = function(options) {
-  var config = util._extend({ parentProperty: 'parent_id', data: [] }, options);
+  var config = util._extend({
+      parentProperty: 'parent_id',
+      data: [],
+      customID: 'id'
+    }, options);
+
   var data = config.data;
 
   if (!util.isArray(data)) {
     throw new Error('Expected an object but got an invalid argument');
   }
 
   var cloned = data.slice();
-  var ordered = orderByParents(cloned);
-  return createTree(ordered, ordered[0]);
+  var ordered = orderByParents(cloned, config);
+  return createTree(ordered, ordered[0], config.customID);
 };

test/fixtures/expected-custom.fixture.js

@@ -0,0 +1,15 @@
+module.exports = [{
+  _id: 1,
+  parent: null,
+  children: [{
+    _id: 2,
+    parent: 1,
+    children: [{
+      _id: 3,
+      parent: 2
+    }]
+  }]
+}, {
+  _id: 4,
+  parent: null
+}];

test/fixtures/initial-custom.fixture.js

@@ -0,0 +1,13 @@
+module.exports = [{
+  _id: 1,
+  parent: null
+}, {
+  _id: 2,
+  parent: 1
+}, {
+  _id: 3,
+  parent: 2
+}, {
+  _id: 4,
+  parent: null
+}];

test/test.js

@@ -3,11 +3,13 @@ var chai = require('chai');
 var expect = chai.expect;
 var toTree = require('../index.js');
 var expected = require('./fixtures/expected.fixture.js');
+var customExpected = require('./fixtures/expected-custom.fixture.js');
+var customInitial = require('./fixtures/initial-custom.fixture.js');
 var initial = require('./fixtures/initial.fixture.js');
 var current;
 
-describe('parent pointer array to tree', function() {
-  describe('expected behavior', function() {
+describe('array-to-tree', function() {
+  describe('with valid arguments', function() {
 
     before(function() {
       current = toTree({ data: initial });
@@ -39,18 +41,45 @@ describe('parent pointer array to tree', function() {
     it('should return an expected value', function() {
       expect(current).to.be.deep.equal(expected);
     });
-
   });
 
-  describe('with incorrect arguments', function() {
+  describe('with invalid arguments', function() {
     it('should return an empty array if the empty array passed', function() {
       expect(toTree({ data: [] })).to.be.deep.equal([]);
     });
 
     it('should throw an error if wrong arguments passed', function() {
-      expect(toTree.bind(null, { data: 'string' })).to.throw(/invalid argument/);
-      expect(toTree.bind(null, { data: {} })).to.throw(/invalid argument/);
+      expect(toTree.bind(null, { data: 'string' }))
+        .to.throw(/invalid argument/);
+
+      expect(toTree.bind(null, { data: {} }))
+        .to.throw(/invalid argument/);
+    });
+
+    it('should return the same array if there is no pointer to parent', function() {
+
+      var modified = initial.map(function(item) {
+        delete item.parent_id;
+        return item;
+      });
+
+      expect(toTree({ data: modified }))
+        .to.be.deep.equal(modified);
     });
 
   })
+
+  describe('with different options', function() {
+    it('should work with custom link to parent', function() {
+
+      var current = toTree({
+        data: customInitial,
+        parentProperty: 'parent',
+        customID: '_id'
+      });
+
+      expect(current)
+        .to.be.deep.equal(customExpected);
+    });
+  });
 });