Create nested Object Array Javascript

Question

I have a list of courses in below json. I have tried to get the desired output to make the array as I want but I am getting the isssues in making the new array.

I am trying to get it using the below snippet but it is showing error for using [courses[i].client_id] with the result.

let courses = [
 {course_id: 1, name: "Test1", description: "Test1 desc", video_url: "111", client_id: 1},
 {course_id: 3, name: "A new course", description: "This is a temporary description used to test functionality. ", video_url: "https://vimeo.com/", client_id: 1},
 {course_id: 5, name: "Teaching", description: "programming language", video_url: "https://vimeo.com", client_id: 1},
 {course_id: 13, name: "Course285", description: "desc285", video_url: "", client_id: 2},
 {course_id: 16, name: "The NEW", description: "The Course is an training", video_url: "https://vimeo.com/", client_id: 1}
]
let result = [];
for (let i = 0; i < courses.length; i++) {
 if (courses && courses.length) {
 result[i][courses[i].client_id] = {
 clientId: courses[i].client_id
 } ;
 }
}

Expected Output

[
 {client_id: 1, courses:[{
 course_id:1,
 course_name: Test1,
 course_desc: description
 },{
 course_id:2,
 course_name: Test1,
 course_desc: description
 }]},
 {client_id:2,courses[{
 ....
 }]}
]

• Nick: what is the result[i]? You not declared this array.
• vikas dhiman: @Nick I forgot during adding the question but in code I declare it as let result = []; before for loop
• GirkovArpa: Your definition of courses is neither valid JSON nor JavaScript. Consider posting an actual working example.
• vikas dhiman: @GirkovArpa a comma is added after first object. Now it is valid. I am sorry I just copy it from browser console and tries to add it.

Answer 1

My case with reduce:

const userCourses = courses.reduce((acc, rec) => {
 const user = acc.find(a=>a.client_id === rec.client_id)
 if (user) {
 user.courses = [...user.courses, {course_id:rec.course_id, course_name: rec.name, course_desc: rec.description}]
 return [...acc]
 }
 return [...acc, { client_id: rec.client_id, courses: [{course_id: rec.course_id, course_name: rec.name, course_desc: rec.description}] }]
}, [])

See in the playground: https://jscomplete.com/playground/s538993

Answer 2

My take on this:

courses
 .map(course => course.client_id)
 .filter((val, idx, arr) => arr.indexOf(val) === idx)
 .map(clientId => ({
 client_id: clientId,
 courses: courses
 .filter(course => course.client_id === clientId)
 .map(course => ({
 course_id: course.course_id,
 course_name: course.name,
 course_desc: course.description
 }))
 }))

• GirkovArpa: Good first answer!
• reded: @GirkovArpa thnx :)

Answer 3

let courses = [{
 course_id: 1,
 name: "Test1",
 description: "Test1 desc",
 video_url: "111",
 client_id: 1
 },
 {
 course_id: 3,
 name: "A new course",
 description: "This is a temporary description used to test functionality. ",
 video_url: "https://vimeo.com/",
 client_id: 1
 },
 {
 course_id: 5,
 name: "Teaching",
 description: "programming language",
 video_url: "https://vimeo.com",
 client_id: 1
 },
 {
 course_id: 13,
 name: "Course285",
 description: "desc285",
 video_url: "",
 client_id: 2
 },
 {
 course_id: 16,
 name: "The NEW",
 description: "The Course is an training",
 video_url: "https://vimeo.com/",
 client_id: 1
 }
]
let result = {}
courses.map(course => {
 let newCourse = {
 course_id: course.course_id,
 course_name: course.name,
 course_desc: course.description
 }
 result[course.client_id] ?
 result[course.client_id].courses.push(newCourse) :
 result[course.client_id] = {
 client_id: course.client_id,
 courses: [newCourse]
 }
})
let output = Object.values(result)
console.log(output)

Answer 4

const courses = [
 { course_id: 1, name: 'Test1', description: 'Test1 desc', video_url: '111', client_id: 1 },
 { course_id: 3, name: 'A new course', description: 'This is a temporary description used to test functionality. ', video_url: 'https://vimeo.com/', client_id: 1 },
 { course_id: 5, name: 'Teaching', description: 'programming language', video_url: 'https://vimeo.com', client_id: 1 },
 { course_id: 13, name: 'Course285', description: 'desc285', video_url: '', client_id: 2 },
 { course_id: 16, name: 'The NEW', description: 'The Course is an training', video_url: 'https://vimeo.com/', client_id: 1 }
]
const output = courses.reduce((output, course) => {
 const { client_id, course_id, name, description } = course;
 const client = () => output.find(client => client.client_id == client_id);
 (client() || output.push({ client_id, courses: [] }) && client())
 .courses.push({ course_id, course_name: name, course_desc: description });
 return output;
}, []);
console.log(output);

Answer 5

let courses = [
 {
 course_id: 1, 
 name: "Test1", 
 description: "Test1 desc",
 video_url: "111", 
 client_id: 1
 },
 {
 course_id: 3, 
 name: "A new course", 
 description: "This is a temporary description used to test functionality. ", 
 video_url: "https://vimeo.com/", 
 client_id: 1
 },
 {
 course_id: 5, 
 name: "Teaching", 
 description: "programming language", 
 video_url: "https://vimeo.com", 
 client_id: 1
 },
 {
 course_id: 13, 
 name: "Course285", 
 description: "desc285", 
 video_url: "", 
 client_id: 2
 },
 {
 course_id: 16, 
 name: "The NEW", 
 description: "The Course is an training", 
 video_url: "https://vimeo.com/", 
 client_id: 1
 }
]
const arr = courses.reduce((acc, obj) => {
 const accObj = acc.find(e => e.client_id == obj.client_id);
 const courseObj = {
 course_id: obj.course_id, 
 course_name: obj.name, 
 course_desc: obj.description
 };
 if (accObj) {
 accObj.courses = [...accObj.courses, courseObj];
 return acc
 }
 return [...acc, { client_id: obj.client_id, courses: [courseObj] }];
}, []);
console.log(arr);