将平面对象数组转换为嵌套对象

Question

I have an array of task objects and I want to transform these into a multidimensional object grouped by ownerID

var tasks = [   
{taskID: "1", title: "task1", ownerID: "100", ownerName: "John", allocation: 80},       
{taskID: "2", title: "task2", ownerID: "110", ownerName: "Sarah", allocation: 50}, 
{taskID: "3", title: "task3", ownerID: "110", ownerName: "Sarah", allocation: 50}, 
{taskID: "4", title: "task4", ownerID: "120", ownerName: "Mike", allocation: 25},
{taskID: "5", title: "task5", ownerID: "120", ownerName: "Mike", allocation: 45}];

This is my expected output:

var people = {

    100:    {   ownerName: "John", 
                tasks:  {       
                            {taskID: "1", title: "task1", allocation: 80}
                        }       
            },

    110:    {   ownerName: "Sarah", 
                tasks:  {       
                            {taskID: "2", title: "task2", allocation: 50}
                            {taskID: "3", title: "task3", allocation: 50}
                        }       
            },

    120:    {   ownerName: "Mike", 
                tasks:  {       
                            {taskID: "4", title: "task4", allocation: 25}
                            {taskID: "5", title: "task5", allocation: 45}
                        }       
            },


    };

I'm looping through the original data and assigning each row

people[ownerID] = {};
person = people[ownerID];
person['ownerName'] = ownerName;
person['tasks'] = {};
person[taskID] = {};
task = person[taskId];
task['taskID'] = taskID;

This seems to group by ownerID fine and creates a nested object of tasks but it will only add one task for each person.

Argh. Any help really appreciated.

Answer 1

Here is a functional way to do it (assuming ownerName is functional dependent on ownerID ):

 const tasks = [ {taskID: "1", title: "task1", ownerID: "100", ownerName: "John", allocation: 80}, {taskID: "2", title: "task2", ownerID: "110", ownerName: "Sarah", allocation: 50}, {taskID: "3", title: "task3", ownerID: "110", ownerName: "Sarah", allocation: 50}, {taskID: "4", title: "task4", ownerID: "120", ownerName: "Mike", allocation: 25}, {taskID: "5", title: "task5", ownerID: "120", ownerName: "Mike", allocation: 45}]; const result = tasks.reduce( (acc, {taskID, title, ownerID, ownerName, allocation }) => { (acc[ownerID] = acc[ownerID] || { ownerName, tasks: [] }) .tasks.push( { taskID, title, allocation } ); return acc; }, {}); console.log(result); 

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Answer 2

people[ownerID] = {};

person['tasks'] = {};

These lines don't check if an object with the same key exists before and create a new object each time.

Try changing it to

people[ownerID] = people[ownerID] || {};

person['tasks'] = person['tasks'] || {};

Answer 3

Just one thing, the tasks should be an array, since objects can't hold another objects without having a key.

var tasks = [   
{taskID: "1", title: "task1", ownerID: "100", ownerName: "John", allocation: 80},       
{taskID: "2", title: "task2", ownerID: "110", ownerName: "Sarah", allocation: 50}, 
{taskID: "3", title: "task3", ownerID: "110", ownerName: "Sarah", allocation: 50}, 
{taskID: "4", title: "task4", ownerID: "120", ownerName: "Mike", allocation: 25},
{taskID: "5", title: "task5", ownerID: "120", ownerName: "Mike", allocation: 45}];

var transformed = tasks.reduce((obj, item)=> {
    if(!obj[item.ownerID]) {
        obj[item.ownerID] = {};
    }
    obj[item.ownerID].ownerName = item.ownerName;
    if(!obj[item.ownerID].tasks) {
        obj[item.ownerID].tasks = [];
    }
    obj[item.ownerID].tasks.push({taskID: item.taskID, title: item.title, allocation: item.allocation})
    return obj;
}, {})
console.log(transformed);

Answer 4

You could use the logical OR as default operator ans assign a new object if the peroperty does not exists.

 var tasks = [{ taskID: "1", title: "task1", ownerID: "100", ownerName: "John", allocation: 80 }, { taskID: "2", title: "task2", ownerID: "110", ownerName: "Sarah", allocation: 50 }, { taskID: "3", title: "task3", ownerID: "110", ownerName: "Sarah", allocation: 50 }, { taskID: "4", title: "task4", ownerID: "120", ownerName: "Mike", allocation: 25 }, { taskID: "5", title: "task5", ownerID: "120", ownerName: "Mike", allocation: 45 }], people = {}; tasks.forEach(({ taskID, title, ownerID, ownerName, allocation }) => { people[ownerID] = people[ownerID] || { ownerName, tasks: {} }; people[ownerID].tasks[taskID] = people[ownerID].tasks[taskID] || { taskID, title, allocation }; }); console.log(people); 

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