I am looking for a way to transform JSON data into a flat "csv-like" data object. In some way, I am looking to "sqlirize" a mongodb collection. I have already check some json flat libraries in NPM but non of them quite solve my problem. I have solved it in my own way but wanted to know if there is a more efficient way.
I have a collection that presents the data through an API in the following way:
[{
"data": {
"name": "John",
"age": 23,
"friends": [{
"name": "Arya",
"age": 18,
"gender": "female"
}, {
"name": "Sansa",
"age": 20,
"gender": "female"
}, {
"name": "Bran",
"age": 17,
"gender": "male"
}]
}
}, {
"data": {
"name": "Daenerys",
"age": 24,
"friends": [{
"name": "Grey Worm",
"age": 20,
"gender": "male"
}, {
"name": "Missandei",
"age": 17,
"gender": "female"
}]
}
}]
This is the function that I have created to reflat a safe-flattened json (e.i.: everything is flattened except arrays)
const { cloneDeep } = require('lodash')
const flatten = require('flat')
const reflatten = (items) => {
const reflatted = []
items.forEach(item => {
let array = false
for (const key of Object.keys(item)) {
if (Array.isArray(item[key])) {
array = true
const children = Array(item[key].length).fill().map(() => cloneDeep(item))
for (let i = 0; i < children.length; i++) {
const keys = Object.keys(children[i][key][i])
keys.forEach(k => {
children[i][`${key}.${k}`] = children[i][key][i][k]
})
delete children[i][key]
reflatted.push(children[i])
}
break
}
}
if (!array) {
reflatted.push(item)
}
})
return reflatted.length === items.length
? reflatted
: reflatten(reflatted)
}
const rows = []
for (const item of items) {
const flat = [flatten(item)]
rows.push(...reflatten(flat)]
}
console.log(rows)
The expected (and current) output is the following:
[{
"data.name": "John",
"data.age": 23,
"data.friends.name": "Arya",
"data.friends.age": 18,
"data.friends.gender": "female"
}, {
"data.name": "John",
"data.age": 23,
"data.friends.name": "Sansa",
"data.friends.age": 20,
"data.friends.gender": "female"
}, {
"data.name": "John",
"data.age": 23,
"data.friends.name": "Bran",
"data.friends.age": 17,
"data.friends.gender": "male"
}, {
"data.name": "Daenerys",
"data.age": 24,
"data.friends.name": "Grey Worm",
"data.friends.age": 20,
"data.friends.gender": "male"
}, {
"data.name": "Daenerys",
"data.age": 24,
"data.friends.name": "Missandei",
"data.friends.age": 17,
"data.friends.gender": "female"
}]
Although I achieved the expected output, I keep wondering if there are other libraries there or if there is a more efficient way of doing it.
Related
Please how can I make this work on mongoDB.
For each item in an array, fetch data which contains the item from another collection.
For example:
"users" : [{
"name": "John doe",
"age": 51
},
{
"name": "Jake kim",
"age": 50
},
{
"name": "Jim son",
"age": 51
}]
On another collection I have
"age": [50,51,52,53,54]
Now my desire result is
"50" : [{
"name": "Jake kim",
"age": 50
}],
"51" : [{
"name": "John doe",
"age": 51
},
{
"name": "Jim son",
"age": 51
}]
You can do this. Get the array of users.
const users = [{ "name": "John doe", "age": 51 }, { "name": "Jake kim", "age": 50 }, { "name": "Jim son", "age": 51 }]
Get the array of ages
const age = [50,51,52,53,54]
Then you can map through the array of ages, returning an object that has the user that has the same age, here is the algorithm.
const mapped = age.map(age => {
const user = {}
user[age] = users.find(ob => ob.age === age);
return user;
})
If you print out the mapped result. This is what it will look like, For the ages that we couldn't find their users, they just have an undefined value.
console.log(mapped)
[
{ '50': { name: 'Jake kim', age: 50 } },
{ '51': { name: 'John doe', age: 51 } },
{ '52': undefined },
{ '53': undefined },
{ '54': undefined }
]
I don't think you'll need the age data in your case. However I've provided the both versions which one use the age list but other does not. Please find them below.
const users = [{ "name": "John doe", "age": 51 }, { "name": "Jake kim", "age": 50 }, { "name": "Jim son", "age": 51 }];
const age = [50, 51, 52, 53, 54];
const desired = users.reduce((prev, cur) => {
(prev[cur.age] ?? (prev[cur.age] = [])).push(cur);
return prev;
}, {});
console.log("This is the expected result", desired);
const desired2 = users.reduce((prev, cur) => {
(prev[cur.age] ?? (prev[cur.age] = [])).push(cur);
return prev;
}, age.reduce((prev, cur) => {
prev[cur] = [];
return prev;
}, {}));
console.log("This is the expected result with empty ages", desired2);
let inputArr = [{
"gender": "MALE",
"name": "A",
"age": 20
},
{
"gender": "MALE",
"name": "B",
"age": 12
},
{
"gender": "FEMALE",
"name": "C",
"age": 16
},
{
"gender": "MALE",
"name": "D",
"age": 21
},
{
"gender": "FEMALE",
"name": "E",
"age": 30
}
]
console.log(JSON.stringify(inputArr.reduce((acc, ele) => {
if (acc[ele["gender"]]) {
acc[ele.gender].members.push(ele);
} else {
acc[ele["gender"]] = {
members: []
}
}
return acc;
}, {})))
I am trying to group users on the basis of gender ,using Array.reduce but the output is not showing all the records that are included in the array ,I am not able to understand the isssue here
Your reducer doesn't push the element when it encounter a gender for the first time, so the first user of each gender is missing from your result
let inputArr = [{"gender": "MALE","name": "A","age": 20},{"gender": "MALE","name": "B","age": 12},{"gender": "FEMALE","name": "C","age": 16},{"gender": "MALE","name": "D","age": 21},{"gender": "FEMALE","name": "E","age": 30}]
console.log(JSON.stringify(inputArr.reduce((acc, ele) => {
if (acc[ele["gender"]]) {
acc[ele.gender].members.push(ele);
} else {
acc[ele["gender"]] = {
members: [ele] // initialise the array with the current user
}
}
return acc;
}, {})))
Another solution, but I don't recommend this if performance matter.
let inputArr = [{
"gender": "MALE",
"name": "A",
"age": 20
},
{
"gender": "MALE",
"name": "B",
"age": 12
},
{
"gender": "FEMALE",
"name": "C",
"age": 16
},
{
"gender": "MALE",
"name": "D",
"age": 21
},
{
"gender": "FEMALE",
"name": "E",
"age": 30
}
]
function groupBy(array, field) {
return array.reduce((acc, item) => ({
...acc,
[item[field]]: [...acc[item[field]] || [], item]
}), {})
}
console.log(groupBy(inputArr, "gender"))
I want to replace existing object with new updated fields using spread operator. But I am not getting the correct result.
Below are my two objects.
let obj1 = [
{
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
{
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
{
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
]
let newObj = {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
I can do it with .map. Below is my code.
let result = obj1.map(item => {
if (item.id === newObj.id) {
return {...item, ...newObj};
}
return item;
});
But I do not want to run the loop and want to acheive by spread operator only.
Example for spread. Which is not working. It's not replacing the object. Instead creating one more.
[...obj1, newObj];
Can someone help me?
JSBIN CODE SNIPPET
Spread syntax doesn't replace the object within array like you used it. Using map is the simplest and understandable way. However if you want to use spread syntax you would first need to find the index to be replaced and then use slice on array
let obj1 = [
{
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
{
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
{
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
]
let newObj = {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
const idx = obj1.findIndex(item => item.id === newObj.id);
obj1 = [...obj1.slice(0, idx), newObj, ...obj1.slice(idx + 1)];
console.log(obj1);
Use Object.assign
The Object.assign() method is used to copy the values of all enumerable own properties from one or more source objects to a target object. It will return the target object.
let obj1 = [
{
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
{
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
{
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
]
let newObj = {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
Object.assign(obj1[2], newObj);
console.log(obj1)
Using .find() to get the target obj
let obj1 = [
{
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
{
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
{
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
]
let newObj = {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
const targetObj = obj1.find(obj => obj.id === newObj.id)
Object.assign(targetObj, newObj);
console.log(obj1)
you should normalize your data by id this way:
obj1 = {
1: {
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
2: {
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
3: {
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
}
newObj = {
3: {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
}
this way you can use spread operator:
{ ...obj1, ...newObj }
in order to normalize you can use the reduce func this way:
const normalized = obj1.reduce((result, obj) => ({ ...result, [obj.id]: obj }), {})
Spread operator is magic but it won't do whatever you want, you will have to loop over and replace the object. Instead of doing a map(), I would prefer find(). The use Object.assign() to achieve what you want.
let obj1 = [
{
"id": 1,
"name": "Michel",
"age": 34,
"email": "michel#gmail.com"
},
{
"id": 2,
"name": "Abby",
"age": 40,
"email": "abby#gmail.com"
},
{
"id": 3,
"name": "Gary",
"age": 40,
"email": "abby#gmail.com"
}
]
let newObj = {
"id": 3,
"name": "Gary",
"age": 23,
"email": "gary#gmail.com"
}
let foundOb = obj1.find(e => e.id === newObj.id);
Object.assign(foundOb, newObj)
console.log(obj1)
You cannot use spread syntax in that way. One solution would be to find index of the object you want to replace by id property and then you could use spread syntax with slice method to create new array with replaced object.
let obj1 = [{"id":1,"name":"Michel","age":34,"email":"michel#gmail.com"},{"id":2,"name":"Abby","age":40,"email":"abby#gmail.com"},{"id":3,"name":"Gary","age":40,"email":"abby#gmail.com"}]
let newObj = {"id":3,"name":"Gary","age":23,"email":"gary#gmail.com"}
const index = obj1.findIndex(({id}) => id == newObj.id)
const result = [...obj1.slice(0, index), newObj, ...obj1.slice(index + 1)]
console.log(result)
I would do something like:
updatedObj = [obj1.map((entry) => entry.id !== newObj.id), newObj]
This would give me the updated object with minimal syntax
I have json:
{
"userList":
[{
"name": "Bob",
"age": 28
},{
"name": "Tom",
"age": 45
},{
"name": "Alice",
"age": 32
}]
}
I want to cut only age and put them to array like : public mainChartData1: Array = [28, 45, 32];
I have started to do that by next code:
const arr = this.users.map(obj => {
var localObj = [];
localObj[obj] = obj.age;
return localObj;
});
But it doesn't work.
You can use a little map function to extract the array age
const inputObject = {
"userList":
[{
"name": "Bob",
"age": 28
},{
"name": "Tom",
"age": 45
},{
"name": "Alice",
"age": 32
}]
};
const output = inputObject.userList.map(user => user.age);
console.log(output);
Say arrayObject is the object you have, following should do it. map will return a new array that will be assigned to ageArray.
let ageArray = arrayObject.userList.map(e => e.age)
I'm trying to find out selected object index from array
But it always return -1 don't know why?
Here is I'm trying to do
I have following array in which their are multiple objects
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}]
And here is my another array that are selected by user
var dList = [{
"name": "abc",
"age": 25,
"school": "xyz pqr",
"isChecked": true
}]
Now I want to find out selected object index from data array and remove this object from that array
if (dList.length > 0) {
for (let i=0; i<dList.length; i++){
delete dList[i]['isChecked']
console.log(dList[i])
console.log(data[0])
console.log(dList[i] == data[0])
let index = data.indexOf(dList[i]);
console.log(index)
data.splice(index, 1);
}
}
Here is just a simple implementation:
if (dList.length > 0) {
for (let i=0; i<dList.length; i++) {
delete dList[i]['isChecked']
console.log(dList[i])
console.log(data[0])
console.log(JSON.stringify(dList[i]) === JSON.stringify(data[0]))
let index = data.findIndex(()=>dList[i]);
console.log(index)
data.splice(index, 1);
}
}
Comparing the objects can be done by just converting it into string using JSON.stringify(ObjectName).
Second instead of using indexOf use findIndex.
Here is the main difference between indexOf and findIndex.
You can only compare two primitive types only so you will not be able to get the index of the object by comparing it.
You should instead compare some primary key which will be unique for each object inside the array.
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}];
var index = data.findIndex(x => x.name=="abc2");
console.log(index);
this is going to meet your demand, a more universal version,if you got unique id,that is going to be the best choice:
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}
];
var dList = [{
"name": "abc",
"age": 25,
"school": "xyz pqr",
"isChecked": true
}];
dList.forEach(function(obj) {
delete obj.isChecked;
data.splice(data.findIndex((o) => {
return Object.getOwnPropertyNames(obj).every(p => obj[p] === o[p]);
}), 1);
});
console.log(data);
another way:
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}
];
var dList = [{
"name": "abc",
"age": 25,
"school": "xyz pqr",
"isChecked": true
}];
dList.forEach(function(obj) {
delete obj.isChecked;
data.splice(data.findIndex((o) => o.name === obj.name && o.age === obj.age && o.school === obj.school && o.school === obj.school), 1);
});
console.log(data);
unrecommended way:
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}
];
var dList = [{
"name": "abc",
"age": 25,
"school": "xyz pqr",
"isChecked": true
}];
dList.forEach(function(obj) {
delete obj.isChecked;
data.splice(data.findIndex((o) => JSON.stringify(o) === JSON.stringify(obj)), 1);
});
console.log(data);
You can use this also
var data = [{
"name": "abc",
"age": 25,
"school": "xyz pqr"
},
{
"name": "abc1",
"age": 26,
"school": "xyz pqr"
},
{
"name": "abc2",
"age": 27,
"school": "xyz pqr"
}];
var dList = [{
"name": "abc",
"age": 25,
"school": "xyz pqr",
"isChecked": true
}]
console.log(data.map(function(d){
return d.name;
}).indexOf(dList[0].name));
You cannot compare two Object Notations(JSON). To compare two JSONs you need to first stringify the object, then JavaScript can compare the two objects for you.
Here is a simple code for you to get what you desire.
if (dList.length > 0) {
for(var i=0; i<data.length; i++){
for(var j=0; j<dList.length; j++){
delete dList[j]['isChecked'];
if(JSON.stringify(data[i]) === JSON.stringify(dList[j])){
let index = data.indexOf(data[i]);//Gets the index of the array
data.splice(index, 1);
console.log(data);
}else{
console.log('Data Not Matched in Array');
}
}
}
}
There is no generic means to determine that an object is equal to another in the sense. Please see Equality comparisons for more information.
You can find and remove objects like below:
Array.prototype.remove = function(elem) {
var indexElement = this.findIndex(el => el.name === elem.name);
console.log(indexElement);
if (indexElement != -1)
this.splice(indexElement, 1);
return this;
};
data.remove(dList[0]);
console.log(data);
Online demo (jsFiddle)
var result= data.filter((item, i, self) => {
if (item.name === 'abc2') {
return { itemIndex: i, obj: item }
}
});
var output = result.map(r => { console.log(r.itemIndex) })
console.log(output);
This will return all objects in which name is abc2. findIndex array method will always return 1 index that might not be the case as people can have the same name.