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);
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.
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.
I have an array of objects of the structure coming from server response of iterated array object like as sample
array[1] ={
"ID": "123",
"Name": "John",
"Age": "15"
}
array[2] ={
"ID": "456",
"Name": "Sue",
"Age": "18"
}
array[n] ={
}
But now I want to append the array values if the condition age below 18 in the following structure of as iterated values of above array
Expected Output:
{
"Stud": [{
"ID": "123",
"Name": "John",
"Age": "15"
}, {
"ID": "456",
"Name": "Sue",
"Age": "18"
},{n........
}]
}
var output = { "Stud" : [] };
for (var i = array.length - 1; i >= 0; i--) {
if (array[i].Age < 18) {
output.Stud.push(array[i]);
}
}
console.log(output);
Simply
var output = { "Stud" : array }; //existing 'array'
You can use array#filter to select objects with age less than or equal to 18.
const response = [{
"ID": "123",
"Name": "John",
"Age": "15"
},{
"ID": "456",
"Name": "Sue",
"Age": "18"
},{
"ID": "459",
"Name": "Jaby",
"Age": "20"
}];
const result = response.filter(o => o.Age <= 18);
var output = {'stud' : result};
console.log(output);
Simply iterate and check whether the age is < 18 or not. If so push that to another array.
var array = [];
var array_below_18 = [];
array[0] ={
"ID": "123",
"Name": "John",
"Age": "15"
}
array[1] ={
"ID": "456",
"Name": "Sue",
"Age": "18"
}
array[1] ={
"ID": "456",
"Name": "Sue",
"Age": "14"
}
for(i=0;i<array.length;++i){
if(parseInt(array[i].Age)<18){
array_below_18.push(array[i]);
}
}
var final_object = {
"Stud" : array_below_18
}
console.log(final_object);
I have an nested array that i want to rebuild based on age value:
//Data
data = {"people":
[{"male_1": [
{"name": "Bob" ,"age": "32"},
{"name":"Mike", "age":"31"}
]},
{"female_2": [
{"name":"Jessica", "age": "24"},
{"name":"Ann", "age": "23"}
]}
[{"male_3": [
{"name": "Tom" ,"age": "31"},
{"name":"John", "age":"29"}
]}, ...
]}
New array should looks like:
people = [{"male_1": [
{"name": "Bob" ,"age": "32"}
]},
[{"male_3": [
{"name": "Tom" ,"age": "31"}
]},
{"female_2": [
{"name":"Jessica", "age": "24"}
]}, ...
]}
Based on this example i need to find the largest age of all "persons" then add this person to array then do same with the next one. The age can be same in this case there is no difference who goes first.
With the next function i can find first one and push it to new array, but how find next one?
var age = 0;
data["people"].forEach(function(item) {
for (var key in item) {
if (item.hasOwnProperty(key)) {
item[key].forEach(function(person) {
if (person.age > age) {
age = person.age;
oldest_person = person
}
});
}
}
});
console.log(oldest_person);
here is another interpretation. This one uses the native Array.prototype.sort as the helper function.
var data = { "people": [{ "male_1": [{ "name": "Bob", "age": "32" }, { "name": "Mike", "age": "31" }] }, { "female_2": [{ "name": "Jessica", "age": "24" }, { "name": "Ann", "age": "23" }] }, { "male_3": [{ "name": "Tom", "age": "31" }, { "name": "John", "age": "29" }] }] },
oldies = [],
peopleByAge = data.people.map(function(group){
for( var name in group ){
group[name] = group[name].sort(sortBy('age'));
oldies.push( group[name][0] );
}
return group;
});
// sort by an object key
function sortBy( key ){
return function(a, b){
return parseInt(a[ key ]) < parseInt(b[ key ]);
}
}
document.write('<pre>' + JSON.stringify({ oldies: oldies.sort(sortBy('age')), peopleByAge: peopleByAge }, 0, 2) + '</pre>');
Try this:
var age = 0;
var oldest_person = [];
var data = {"people":
[
{"male_1": [
{"name": "Bob" ,"age": "32"},
{"name":"Mike", "age":"31"}
]},
{"female_2": [
{"name":"Jessica", "age": "24"},
{"name":"Ann", "age": "23"}
]},
{"male_3": [
{"name": "Tom" ,"age": "31"},
{"name":"John", "age":"29"}
]}
]};
data["people"].forEach(function(item) {
for (var key in item) {
if (item.hasOwnProperty(key)) {
var age = 0;
var name = key;
var oldest = null;
item[key].forEach(function(person) {
// Determine the oldest person in each group ("male_1", "female_2", "male_3", ...)
if (person.age > age) {
age = person.age;
oldest = person;
}
});
// Push the oldest person into the 'oldest_person' array
var group = {};
group[name] = [ oldest ];
oldest_person.push(group);
}
}
});
console.log(oldest_person);
You can use some Array methods, like Array.prototype.forEach(), Array.prototype.reduce() and Object.keys().
var data = { "people": [{ "male_1": [{ "name": "Bob", "age": "32" }, { "name": "Mike", "age": "31" }] }, { "female_2": [{ "name": "Jessica", "age": "24" }, { "name": "Ann", "age": "23" }] }, { "male_3": [{ "name": "Tom", "age": "31" }, { "name": "John", "age": "29" }] }] },
people = [];
data.people.forEach(function (a) {
Object.keys(a).forEach(function (k) {
var o = {};
o[k] = a[k].reduce(function (c, d) {
return c.age > d.age ? c : d;
});
people.push(o);
});
});
document.write('<pre>' + JSON.stringify(people, 0, 4) + '</pre>');