Develop Reference

How to filter records in a nested array using ramda?

I've seen this question in several places but still can't figure this out.
Using ramda, how can I filter the following object to return the records that are true for tomatoes?
[
{
"id": "a",
"name": "fred",
"food_prefs": {
"tomatoes": true,
"spinach": true,
"pasta": false
},
"country": "singapore"
},
{
"id": "b",
"name": "alexandra",
"food_prefs": {
"tomatoes": false,
"spinach": true,
"pasta": true
},
"country": "france"
},
{
"id": "c",
"name": "george",
"food_prefs": {
"tomatoes": true,
"spinach": false,
"pasta": false
},
"country": "argentina"
}
]
Storing this array as myData object, I thought that the following should work:
const R = require("ramda")
const lovesTomatoes = R.pipe ( // taken from: https://stackoverflow.com/a/61480617/6105259
R.path (["food_prefs"]),
R.filter (R.prop ("tomatoes"))
)
console.log(lovesTomatoes(myData))
But I end up with the error:
if (typeof obj[methodNames[idx]] === 'function') {
What am I doing wrong?
EDIT
The answers provided by #Ori Drori and #ThanosDi are both great, but I want to emphasize that a pipe-based solution would be ideal because I have follow-up steps I wish to carry on the filtered array. Consider for example the following array. It's similar the one above, but includes more data: year_born and year_record.
[
{
"id": "a",
"name": "fred",
"year_born": 1995,
"year_record": 2010,
"food_prefs": {
"tomatoes": true,
"spinach": true,
"pasta": false
},
"country": "singapore"
},
{
"id": "b",
"name": "alexandra",
"year_born": 2002,
"year_record": 2015,
"food_prefs": {
"tomatoes": false,
"spinach": true,
"pasta": true
},
"country": "france"
},
{
"id": "c",
"name": "george",
"year_born": 1980,
"year_record": 2021,
"food_prefs": {
"tomatoes": true,
"spinach": false,
"pasta": false
},
"country": "argentina"
}
]
So, for example, to answer a full question such as "for those who love tomatoes, what is the average age at the time of the record creation?"
we would need to:
filter the records that love tomates;
extract the elements year_born and year_record
get the difference between values
take the average of the differences
Therefore, using a pipe would be very beneficial.

What went wrong?
You try to get the value of food_prefs out of the array. Since the array doesn't have this key - R.path (["food_prefs"]) is undefined, and then you try to filter this undefined value.
How to solve this problem?
Filter the array, and use R.path to get the tomatoes value.
const { filter, path, identity } = R
const lovesTomatoes = filter(path(['food_prefs', 'tomatoes']))
const data = [{"id":"a","name":"fred","food_prefs":{"tomatoes":true,"spinach":true,"pasta":false},"country":"singapore"},{"id":"b","name":"alexandra","food_prefs":{"tomatoes":false,"spinach":true,"pasta":true},"country":"france"},{"id":"c","name":"george","food_prefs":{"tomatoes":true,"spinach":false,"pasta":false},"country":"argentina"}]
const result = lovesTomatoes(data)
console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.28.0/ramda.min.js" integrity="sha512-t0vPcE8ynwIFovsylwUuLPIbdhDj6fav2prN9fEu/VYBupsmrmk9x43Hvnt+Mgn2h5YPSJOk7PMo9zIeGedD1A==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
Filtering using a pipe:
Using R.pipe. I wouldn't go this way for a simple filter by nested properties, but you can use a Schwartzian transform. The idea is to create a new array if pairs [value of tomatoes, original object], filter by the value of tomatoes, and then extract the original object:
const { pipe, map, applySpec, path, identity, filter, last, head } = R
const lovesTomatoes = pipe(
map(applySpec([path(['food_prefs', 'tomatoes']), identity])), // create an array of [value of tomatoes, original object]
filter(head), // filter by the value of the tomatoes
map(last) // extract the original object
)
const data = [{"id":"a","name":"fred","food_prefs":{"tomatoes":true,"spinach":true,"pasta":false},"country":"singapore"},{"id":"b","name":"alexandra","food_prefs":{"tomatoes":false,"spinach":true,"pasta":true},"country":"france"},{"id":"c","name":"george","food_prefs":{"tomatoes":true,"spinach":false,"pasta":false},"country":"argentina"}]
const result = lovesTomatoes(data)
console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.28.0/ramda.min.js" integrity="sha512-t0vPcE8ynwIFovsylwUuLPIbdhDj6fav2prN9fEu/VYBupsmrmk9x43Hvnt+Mgn2h5YPSJOk7PMo9zIeGedD1A==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>
How to combine the 1st lovesTomatoes filtering function in a pipe:
However, if you just need the pipe to perform other operations on the filtered array, use the filter as one of the steps:
const { filter, path, identity, pipe, map, prop, uniq } = R
const lovesTomatoes = filter(path(['food_prefs', 'tomatoes']))
const countriesOfTomatoLovers = pipe(
lovesTomatoes,
map(prop('country')),
uniq
)
const data = [{"id":"a","name":"fred","food_prefs":{"tomatoes":true,"spinach":true,"pasta":false},"country":"singapore"},{"id":"b","name":"alexandra","food_prefs":{"tomatoes":false,"spinach":true,"pasta":true},"country":"france"},{"id":"c","name":"george","food_prefs":{"tomatoes":true,"spinach":false,"pasta":false},"country":"argentina"}]
const result = countriesOfTomatoLovers(data)
console.log(result)
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.28.0/ramda.min.js" integrity="sha512-t0vPcE8ynwIFovsylwUuLPIbdhDj6fav2prN9fEu/VYBupsmrmk9x43Hvnt+Mgn2h5YPSJOk7PMo9zIeGedD1A==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

const myData = [
{
"id": "a",
"name": "fred",
"food_prefs": {
"tomatoes": true,
"spinach": true,
"pasta": false
},
"country": "singapore"
},
{
"id": "b",
"name": "alexandra",
"food_prefs": {
"tomatoes": false,
"spinach": true,
"pasta": true
},
"country": "france"
},
{
"id": "c",
"name": "george",
"food_prefs": {
"tomatoes": true,
"spinach": false,
"pasta": false
},
"country": "argentina"
}
];
const lovesTomatoes = filter(pathOr(false, ['food_prefs','tomatoes']));
lovesTomatoes(myData);
Ramda REPL

Ramda comes with a whole suite of predicates built-in already,
one of them that I'd use here is pathEq.
I'd suggest to adopt a map and reduce kind of approach, whereas the match function is separated from the actual aggregation...
Collect your data point
Reduce it to the information you need
const tomatoLovers = R.filter(
R.pathEq(['food_prefs', 'tomatoes'], true),
);
const avgAge = R.pipe(R.pluck('age'), R.mean);
const data = [{
"id": "a",
age: 16,
"name": "fred",
"food_prefs": {
"tomatoes": true,
"spinach": true,
"pasta": false
},
"country": "singapore"
},
{
"id": "b",
age: 66,
"name": "alexandra",
"food_prefs": {
"tomatoes": false,
"spinach": true,
"pasta": true
},
"country": "france"
},
{
"id": "c",
age: 44,
"name": "george",
"food_prefs": {
"tomatoes": true,
"spinach": false,
"pasta": false
},
"country": "argentina"
}
]
console.log(
'Average age of tomato lovers is:',
R.pipe(tomatoLovers, avgAge) (data),
);
console.log(
'They are the tomato lovers',
R.pipe(tomatoLovers, R.pluck('name')) (data),
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.28.0/ramda.js" integrity="sha512-ZZcBsXW4OcbCTfDlXbzGCamH1cANkg6EfZAN2ukOl7s5q8skbB+WndmAqFT8fuMzeuHkceqd5UbIDn7fcqJFgg==" crossorigin="anonymous" referrerpolicy="no-referrer"></script>

how to foreach array to array object in javascript

I'm very confused about doing foreach array to array object in Javascript, I already did a lot of research about foreach object in Javascript and I tried many ways but nothing works. All that I'm trying to achieve is to have data JSON like this :
[
{
"name": "First Data",
"data": [
{
"y": 95,
"total":100,
"md": "1",
"name": "National",
"drillup" : 'level0',
"drilldown" : "3",
"next" : "level2"
}
]
}
,{
"name": "Second Data",
"data": [
{
"y": 95,
"total":100,
"md": "1",
"name": "National",
"drillup" : 'National',
"drilldown" : "3",
"next" : "level2"
}
]
}
]
and I tried to do foreach based on some finding of my research but the result wasn't like what I want or like what I'm try to achieve ..
and here is the script that I tried :
dataFirstSecond = await informationModel.getdata();
Object.entries(dataRegularSecondary).forEach(entry => {
const [key, value] = entry;
returnData[key] = [
{
name: value.name,
data: [{
y: value.y,
total: value.total_ada,
next: 'level_2',
drilldown: true,
}]
}]
});
and here is the result or the output of my script that I try it :
{
"0": [
{
"name": "First Data",
"data": [
{
"y": 22.973,
"total": 17,
"next": "level_2",
"drilldown": true
}
]
}
],
"1": [
{
"name": "Second Data",
"data": [
{
"y": 5.4054,
"total": 4,
"next": "level_2",
"drilldown": true
}
]
}
]
}
can someone help me to achieve the data that I want?

returnData[key] = [{ ... }] should just be returnData.push({ ... }), and make sure returnData is an array (e.g. returnData = [])

If the function informationModel.getdata(); returns an Object you could use the method JSON.stringify(Object) to easily convert and Object to JSON. For example you could try to do to convert this Object to a String then cast the String to JSON.
let JSONString = JSON.stringify(informationModel.getdata());
let JSON_Object = JSON.parse(JSONString);

If dataRegularSecondary is an array and not an object you could use map:
dataRegularSecondary.map(value => {
return {
name: value.name,
data: [{
y: value.y,
total: value.total_ada,
next: 'level_2',
drilldown: true,
}]
}
}

Your question is how to forEach array to array object. Then that means dataRegularSecondary is an array, right? Object.entries returns an array of key value pairs. If you pass an array to that method, it will return the indices as keys and the items as values.
const arr = ['hello', 'world'];
Object.entries(arr); // [['0', 'hello'], ['1', 'world']]
Skip the Object.entries and use dataRegularSecondary directly for forEach.
As for your output, it looks like returnData is an object as well. Make sure it's an array and just push the data into that.
dataRegularSecondary.forEach(value => {
returnData.push({
name: value.name,
data: [{
y: value.y,
total: value.total_ada,
next: 'level_2',
drilldown: true,
}],
});
});
Or you can use map as well.
const returnData = dataRegularSecondary.map(value => ({
name: value.name,
data: [{
y: value.y,
total: value.total_ada,
next: 'level_2',
drilldown: true,
}],
}));

how to make nested array objects in javascript in a key value pair format

array data=[
{
"id":1,
"name":"john",
"income":22000,
"expenses":15000
},
{
"id":2,
"name":"kiran",
"income":27000,
"expenses":13000
},
{
"id":1,
"name":"john",
"income":35000,
"expenses":24000
}
]
i want to make a new array set in following format which is in a key value pair. ie result set.
can you please explain the best method. ? how to achive using foreach.?
tried using foreach method by looping each element. but cant get the desired output format
var result= [ {
"name": "john",
"series": [
{
"name": "income",
"value": 22000
},
{
"name": "expenses",
"value": 15000
},
]
},
{
"name": "kiran",
"series": [
{
"name": "income",
"value": 27000
},
{
"name": "expenses",
"value": 13000
},
]
}]

// Your array
const result = [
{
name: "john",
series: [
{
name: "income",
value: 22000,
},
{
name: "expenses",
value: 15000,
},
],
},
{
name: "kiran",
series: [
{
name: "income",
value: 27000,
},
{
name: "expenses",
value: 13000,
},
],
},
];
// What is .map function?
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map
// Output
// map return a new function.
// it's a loop method but more equipped
result.map((item, index) => {
const seriesKeyValues = {};
// forEach is too, it's a loop method.
// but not have a return value,
// just loops and give you item on each loop
item.series.forEach(serie => {
//seriesKeyValues is a object.
// different between seriesKeyValues.serie.name
// it's a bracket notation
// look this documentation
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#computed_property_names
seriesKeyValues[serie.name] = serie.value;
});
// return new Object
// ... is 'spread syntax' basically combine objects
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#spread_properties
// spread syntax is a new way.
// old way is https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
return {
id: index,
name: item.name,
...seriesKeyValues,
};
});
I hope it will help :). if you don't understand any lines of code, i can explain

Functional immutable way in javascript to copy an array with additional items in certain positions depending on condition on items

I have an array:
[
{ "name": "batman", "hasSidekick": true },
{ "name": "shazam!", "hasSidekick": false },
{ "name": "capt america", "hasSidekick": true },
{ "name": "spiderman", "hasSidekick": false }
]
From this, I want to create a new array of hero names which will have all of the above names but when hasSidekick is true for a hero, there should be an additional name inserted after it.
Expected output:
[
"batman",
"batman's sidekick",
"shazam!", ,
"capt america",
"capt america's sidekick",
"spiderman"
]
I can do it with forEach and pushing additional items conditionally based on hasSidekick:
const heroes = [
{ name: "batman", hasSidekick: true },
{ name: "shazam!", hasSidekick: false },
{ name: "capt america", hasSidekick: true },
{ name: "spiderman", hasSidekick: false },
];
let heroesAndSidekicks = [];
heroes.forEach(hero => {
heroesAndSidekicks.push(hero.name);
if (hero.hasSidekick) {
heroesAndSidekicks.push(`${hero.name}'s sidekick`);
}
});
console.log(heroesAndSidekicks);
But please suggest how I can do it in functional programming way without mutation.

You could take Array#flatMap.
var data = [{ name: "batman", hasSidekick: true }, { name: "shazam!", hasSidekick: false }, { name: "capt america", hasSidekick: true }, { name: "spiderman", hasSidekick: false }],
result = data.flatMap(({ name, hasSidekick }) => hasSidekick
? [name, name + '\'s sidekick']
: name
);
console.log(result);

I think Array.prototype.reduce() can solve your issue. From the documentation:
The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in a single output value.
Please find a possible solution below:
const data = [
{ "name": "batman", "hasSidekick": true },
{ "name": "shazam!", "hasSidekick": false },
{ "name": "capt america", "hasSidekick": true },
{ "name": "spiderman", "hasSidekick": false }
];
const result = data.reduce((a, e) => {
a.push(e.name);
if (e.hasSidekick) {
a.push(`${e.name}'s sidekick`);
}
return a;
}, []);
console.log(result);
I hope that helps!

How can I flatten nested arrays in JavaScript?

I have complicated array with nested arrays.
For example if I want to get data from last array then I have to write:
partners[0].products[0].campaigns[0].nameCampaign or .type or .price etc.
I'd like to flatten this array. And this is what I expect:
Is it possible at all?
#EDIT
This is part of console.log(JSON.stringify(partners, 0, 4));:
[{
"_id": "57727902d0a069e41a34eece",
"namePartner": "Self",
"products": [{
"_id": "57727910d0a069e41a34eed0",
"nameProduct": "Singl",
"campaigns": [{
"_id": "57727937d0a069e41a34eed1",
"type": "lead",
"nameCampaign": "Camp 0"
}]
}, {
"_id": "5774cb68c594b22815643b37",
"nameProduct": "DrugiPartner"
"campaigns": [{
"_id": "5774cb78c594b22815643b38",
"type": "subscription",
"nameCampaign": "DrugaKampania"
}, {
"_id": "5774cbedc594b22815643b3a",
"type": "subscription",
"nameCampaign": "TrzeciaKampania"
}, {
"_id": "5774cbf9c594b22815643b3b",
"type": "subscription",
"nameCampaign": "CzwartaKampania"
}]
}, {
"_id": "5774cbdbc594b22815643b39",
"nameProduct": "Trzeci"
"campaigns": []
}]
}]

In plain Javascript you could use an array with the references to the wanted items and the arrays and use an iterative recursive approach to get the wanted array.
Edit
For more than one property to add, you could use an array for more than one item.
One property:
{ use: 'namePartner' }
Multiple properties:
{ use: ['nameCampains', 'type'] }
function iter(a, r, l) {
if (Array.isArray(a)) {
a.forEach(function (b) {
var use = level[l].use,
rr = JSON.parse(JSON.stringify(r));
(Array.isArray(use) && use || [use]).forEach(function (c) {
rr[c] = b[c];
});
iter(b[level[l].array], rr, l + 1);
});
return;
}
result.push(r);
}
var partners = [{ namePartner: 'Tesco', products: [{ nameProduct: 'New', campains: [{ nameCampains: 'Apple', type: 'appleType' }, { nameCampains: 'Lenovo', type: 'lenovoType' }] }] }, { namePartner: 'Eko', products: [{ nameProduct: 'Fresh', campains: [{ nameCampains: 'Asus', type: 'asusType' }, { nameCampains: 'Dell', type: 'dellType' }] }, { nameProduct: 'new', campains: [{ nameCampains: 'Samsung', type: 'samsungType' }] }] }],
level = [{ use: 'namePartner', array: 'products' }, { use: 'nameProduct', array: 'campains' }, { use: ['nameCampains', 'type'] }],
result = [];
iter(partners, {}, 0);
console.log(result);

You could use get from lodash:
var CAMPAIGN_NAME_PATH = ['partners', 0, 'products', 0, 'campaigns', 0, 'nameCampaig'];
var campaignName = _.get(JSONObject, CAMPAIGN_NAME_PATH, 'optionalDefaultCampaignName');
Or you could try playing with flatten, flattenDeep and flattenDepth and rearrange the JSON object structure first before accessing it (note that these three methods only work on arrays, not key-value objects).