Loop into Array of Objects comparing two arrays - PUG (Jade) - javascript

I am trying in Javascript, using PUG template (if possible), to compare two arrays and when I find a correspondance in IDs, display some particular elements.
// First Array : I iterate over "hearts" object
// Called in PUG : - const user
[
{
"hearts": [
"5e70c63a94b27b164c9b897f",
"5e723c75e4bfdf4f58c55e32"
],
"_id": "5e6bb1189978fd5afc98c57a",
"email": "catherine#catherine.com",
"name": "Catherine",
"photo": "0121b7fe-b2ae-4e75-979d-7dea1a432855.jpeg",
"__v": 0
},
{
"hearts": [
"5e723c75e4bfdf4f58c55e32"
],
"_id": "5e6bc41f5915e3d2980a5174",
"email": "marc#marc.com",
"name": "Marc",
"photo": "4caa7bfb-6408-4893-a78b-fa6e8e5b03e7.png",
"__v": 0
}
]
// Second array : I iterate over "author.hearts" object
// Called in PUG : - const store
[{
"product": {
"categories": [
1,
2
]
},
"_id": "5e6bcc76c4022eae00e22af6",
"date": "2222-02-20T21:22:00.000Z",
"author": {
"hearts": [
"5e723c75e4bfdf4f58c55e32",
"5e70c63a94b27b164c9b897f"
],
"_id": "5e6bb1189978fd5afc98c57a",
"__v": 0
},
"created": "2020-03-13T18:09:58.086Z",
"id": "5e6bcc76c4022eae00e22af6"
}]
I want to loop over the first array, find the first ID (here 5e70c63a94b27b164c9b897f), loop over the second array and see if this ID is present within the "author.hearts" object. If it is not, carry on with the second ID and if it is present, display all the keys (tags, photos, _id, date...) from the object where the ID was found.
In my example, I have just one object in my array, but I'll be having much more later on.
Many thanks for your help

If I'm understanding correctly you can do something like this. Loop through all your users and when you find their id in author.hearts stop the loop there and return the object the user's _id was found in.
var resultFound = undefined;
try {
user.forEach((el) => {
const id = el._id;
const result = store.find(el => el.author.hearts.includes(id));
if (result) {
resultFound = result;
throw resultFound;
}
});
} catch (e) {
if (e !== resultFound) {
throw e;
}
}

Related

Taking contents of an array of objects, and assigning them to a property on a JSON object

I want to take items from this array (the way I save things on the client)
[
{
"id": "-Mdawqllf_-BaW63gMMM",
"text": "Finish the backend[1]",
"status": true,
"time": 1625248047800
},
{
"id": "-Mdawqllf_-BaW63gGHf",
"text": "Finish the middle-end[2]",
"status": false,
"time": 1625248040000
},
{
"id": "-Mdawqllf_-BaW63gGHd",
"text": "Finish the front-end[3]",
"status": false,
"time": 1625248040000
}
]
And turn them into this format for how I save it server side
{ "todos": {
"-Mdawqllf_-BaW63gMMM": {
"text": "Finish the backend[1]",
"status": true,
"time": 1625248047800,
},
"-Mdawqllf_-BaW63gGHf": {
"text": "Finish the middle-end[2]",
"status": false,
"time": 1625248040000,
},
"-Mdawqllf_-BaW63gGHd": {
"text": "Finish the front-end[3]",
"status": false,
"time": 1625248040000,
}
},
}
Basically i turn items into an array on the client to help with sorting and making use of arrays. But before sending it back need to put into the right format
Use .map() to loop over the array of objects to exctract the id property, so you can use it as the key of the new object.
Use Object.fromEntries() to create the new object from the array returned by .map().
const data = [
{
"id": "-Mdawqllf_-BaW63gMMM",
"text": "Finish the backend[1]",
"status": true,
"time": 1625248047800
},
{
"id": "-Mdawqllf_-BaW63gGHf",
"text": "Finish the middle-end[2]",
"status": false,
"time": 1625248040000
},
{
"id": "-Mdawqllf_-BaW63gGHd",
"text": "Finish the front-end[3]",
"status": false,
"time": 1625248040000
}
];
const todos = {
Todos: Object.fromEntries(data.map(obj => [obj.id, obj]))
};
console.log(todos);
#Barmar's solutions is nice.
For the sake of learning or others googling. You can also reduce the array to an object.
const todos = data.reduce((obj, item) => {
obj[item.id] = item
return obj
}, {})
const items = {
todos: {
...data
}
};
Assume that data is the array of objects.
Use the spread operator to copy all the array objects from data array to the todos object at key todos.
One important thing to note that you can't assign more than one objects without array to a single object key. You definately have to use the array to maintain all the objects under the one key.
Avoid using the hardcode index. Always use the spread operator

How to get JSON entry from returned objects

I got JSON data, like:
{
"id": 1,
"active": true,
"dependency": [
{ "id": 2 }
{ "id": 3 }
]
},
{
"id": 2,
"active": true
},
{
"id": 3,
"active": true
}
I want to retrieve the "active" value for each dependency in the id 1 object. So far I used a forEach to get those dependency.
thisElement.dependency.forEach(function(id) {
console.log(id)
}
Which returns id 2 and id 3 as objects. Is there a way to use id.active straight away? By using only one loop? Because the result so far are objects without any connection to the related JSON data. Would it require to loop through the whole JSON data to retrieve those values?
The most efficient thing to to is create a hashmap with an Object or Map first so you only need to iterate the array once to find dependency related values.
You could do it by using Array#find() to search whole array each time but that is far more time complexity than the o(1) object lookup
const activeMap = new Map(data.map(obj => [obj.id, obj.active]))
data[0].dependency.forEach(({id}) => console.log(id ,' active: ' , activeMap.get(id)))
<script>
const data =
[
{
"id": 1,
"active": true,
"dependency": [
{"id": 2 },
{"id": 3}
]
},
{
"id": 2,
"active": false
},
{
"id": 3,
"active": true
}
]
</script>

Query Comparing Arrays of Objects

I'm wondering how I can compare arrays of (nested) objects in Mongoose.
Considering the data below, I would like to get results when the name properties match. Could anyone help me with this?
Organisation.find( {
$or: [
{ "category_list": { $in: cat_list } },
{ "place_topics.data": { $in: place_tops } }
]
}
)
Let's say that this is the data stored in my MongoDB:
"category_list": [
{
"id": "197750126917541",
"name": "Pool & Billiard Hall"
},
{
"id": "197871390225897",
"name": "Cafe"
},
{
"id": "218693881483234",
"name": "Pub"
}
],
"place_topics": {
"data": [
{
"name": "Pool & Billiard Hall",
"id": "197750126917541"
},
{
"name": "Pub",
"id": "218693881483234"
}
]
}
And let's say that these are the arrays I want to compare against (almost the same data):
let cat_list = [
{
"id": "197750126917541",
"name": "Pool & Billiard Hall"
},
{
"id": "197871390225897",
"name": "Cafe"
},
{
"id": "218693881483234",
"name": "Pub"
}
]
let place_tops = [
{
"name": "Pool & Billiard Hall",
"id": "197750126917541"
},
{
"name": "Pub",
"id": "218693881483234"
}
]
When there are "multiple conditions" required for each array element is when you actually use $elemMatch, and in fact "need to" otherwise you don't match the correct element.
So to apply multiple conditions, you would rather make an array of conditions for $or instead of shortcuts with $in:
Organizations.find({
"$or": [].concat(
cat_list.map( c => ({ "category_list": { "$elemMatch": c } }) ),
place_tops.map( p => ({ "place_topics": { "$elemMatch": p } }) )
)
})
However, if you take a step back and think logically about it, you actually named one of the properties "id". This would generally imply in all good practice that the value is in fact ""unique".
Therefore, all you really should need to do is simply extract those values and stick with the original query form:
Organizations.find({
"$or": [
{ "category_list.id": { "$in": cat_list.map(c => c.id) } },
{ "place_topics.id": { "$in": place_tops.map(p => p.id) } }
]
})
So simply mapping both the values and the property to "match" onto the "id" value instead. This is a simple "dot notation" form that generally suffices when you have one condition per array element to test/match.
That is generally the most logical approach given the data, and you should apply which one of these actually suits the data conditions you need. For "multiple" use $elemMatch. But if you don't need multiple because there is a singular match, then simply do the singular match

Javascript create an object, keyed by array value

I have a method which needs to return a user object from a supplied id parameter. Further methods will use this structure so it's not a simple case of using the existing structure.
Essentially I have a database which contains a type key, this is filtered so that I have a collection of users. What I need to do is create an object which is keyed by the users _id value and contains the users object with the _id and type omitted.
Using lodash or some ES6 sugar I would like to transform the following Array;
[
{
"_id": "0e12e661cb50068a135b36067f001d20",
"name": "Joe Bloggs",
"type": "user"
},
{
"_id": "0e12e661cb50068a135b36067f00373f",
"name": "Ben Bloggs",
"type": "user"
}
]
Into the following Object, with the _id and type omitted;
{
"0e12e661cb50068a135b36067f001d20": {
"name": "Joe Bloggs"
},
"0e12e661cb50068a135b36067f00373f": {
"name": "Ben Bloggs"
}
}
EDIT I need to return the object and NOT the name as further properties could be added to these objects.
You can do this with just reduce().
var data = [{
"_id": "0e12e661cb50068a135b36067f001d20",
"name": "Joe Bloggs",
"type": "user"
}, {
"_id": "0e12e661cb50068a135b36067f00373f",
"name": "Ben Bloggs",
"type": "user"
}]
var result = data.reduce(function(r, e) {
r[e._id] = {name: e.name};
return r;
}, {})
console.log(result)
ES6 version with arrow function
var result = data.reduce((r, e) => (r[e._id] = {name: e.name}, r), {})
Update: To just exclude specific properties from new object you can use Object.assign() DEMO to create copy of object and then delete to delete some properties or you can use forEach() loop and add properties that you want DEMO

Wildcard Search in a collection with lodash

I've an array like the one shown below and I want to do a wildcard search and retrieve the corresponding value. This is not returning me any result, can someone help me if there is any better way to do this. I'm using lodash utilities in my nodejs application.
var allmCar = [
{
"_id": ObjectId("5833527e25bf78ac0f4ca30e"),
"type": "mCar",
"value": "ABDC",
"__v": 0
},
{
"_id": ObjectId("5833527e25bf78ac0f4ca30e"),
"type": "mCar",
"value": "XYZ ABD",
"__v": 0
},
{
"_id": ObjectId("5833527e25bf78ac0f4ca30e"),
"type": "mCar",
"value": "FGHJ",
"__v": 0
}
]
_.find(allmCar, {
value: {
$regex: 'XYZ'
}
})
I finally ended up using _.includes as below
_.each(allmCar,function(car){
if(_.includes('XYZ', car.value)===true)
return car;
})
You can do the same with a function passed to _.find, like this
_.find(allmCar, function(mCar) {
return /XYZ/.test(mCar.value);
});
Or with arrow functions,
_.find(allmCar, (mCar) => /XYZ/.test(mCar.value));
This will apply the function passed to all the items of the collection and if an item returns true, that item will be returned.

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