Javascript create an object, keyed by array value - javascript

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

Related

Destructuring object with inner array without all keys

I have an object like this:
const objBefore:
{
"id": "3pa99f64-5717-4562-b3fc-2c963f66afa1",
"number": "5000",
"enabled": true,
"classes": [
{
"id": "2fc87f64-5417-4562-b3fc-2c963f66afa4",
"name": "General"
},
{
"id": "7ffcada8-0215-4fb0-bea9-2266836d3b18",
"name": "Special"
},
{
"id": "6ee973f7-c77b-4738-b275-9a7299b9b82b",
"name": "Limited"
}
]
}
Using es6, I want to grab everything in the object except the name key of the inner classes array to pass it to an api.
So:
{
"id": "3pa99f64-5717-4562-b3fc-2c963f66afa1",
"number": "5000",
"enabled": true,
"classes": [
{"id": "2fc87f64-5417-4562-b3fc-2c963f66afa4"},
{"id": "7ffcada8-0215-4fb0-bea9-2266836d3b18"},
{"id": "6ee973f7-c77b-4738-b275-9a7299b9b82b"}
]
}
The closest I got was: let {id, number, enabled, classes: [{id}]} = objBefore;
But it only gets me one id in classes. I've tried spreading above using [...{id}] or [{...id}]. Same thing.
I find it challenging to get the right mental model for how to think about this when it's on multiple levels. In my mind, when I say [...{id}] I'm thinking, "I want the id property as an object in the outer classes array, but give me every id in the array!"
Clearly I'm not thinking about this correctly.
I've tried it using map to get that part but I'm still having trouble combining it back to the original to produce the desired result. for example:
let classIds = objBefore.classes.map(({id}) => {
return {
id
}
})
(Using the map syntax, how can I destructure in the function the other keys that are one level higher?)
To combine them I started trying anything and everything, :
let {id, number, enabled, classIds} = {objBefore, [...classIds]} // returns undefined for all
I'd prefer to do it in one statement. But if that's not possible, then what's a clean way to do it using map?.
You can't destructure and map at the same time in the way you're looking to do it. The main purpose of destructuring assignment is to extract data from an array/object and not for manipulating data. In your case, as you're after an object with the same keys/value as your original object, just with a different classes array, I would instead suggest creating a new object and spreading ... the original object into that. Then you can overwrite the classes array with a mapped version of that array:
const objBefore = { "id": "3pa99f64-5717-4562-b3fc-2c963f66afa1", "number": "5000", "enabled": true, "classes": [ { "id": "2fc87f64-5417-4562-b3fc-2c963f66afa4", "name": "General" }, { "id": "7ffcada8-0215-4fb0-bea9-2266836d3b18", "name": "Special" }, { "id": "6ee973f7-c77b-4738-b275-9a7299b9b82b", "name": "Limited" } ] };
const newObj = {
...objBefore,
classes: objBefore.classes.map(({id}) => ({id}))
};
console.log(newObj);
How about using simple util method with object destructuring, spread operator and map
const objBefore = {
id: "3pa99f64-5717-4562-b3fc-2c963f66afa1",
number: "5000",
enabled: true,
classes: [
{
id: "2fc87f64-5417-4562-b3fc-2c963f66afa4",
name: "General",
},
{
id: "7ffcada8-0215-4fb0-bea9-2266836d3b18",
name: "Special",
},
{
id: "6ee973f7-c77b-4738-b275-9a7299b9b82b",
name: "Limited",
},
],
};
const process = ({ classes, ...rest }) => ({
...rest,
classes: classes.map(({ id }) => ({ id })),
});
console.log(process(objBefore))
In one line, you could do this:
const objAfter = { ...objBefore, classes: objBefore.classes.map(item => ({ id: item.id })) };
Or, if you prefer:
const objAfter = {...objBefore, classes: objBefore.classes.map(({id}) => ({id}))};
There isn't any way in object destructing to copy an entire array of objects into a different array of objects by removing properties so you use .map() for that.

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

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;
}
}

Retrive array object from object in Javascript

var obj={"firstName":"John","lastName":"Smith","isAlive":true,"age":25,"address":{"streetAddress":"21 2nd Street","city":"New York","state":"NY","postalCode":"10021-3100"},"phoneNumbers":[{"type":"home","number":"212 555-1234"},{"type":"office","number":"646 555-4567"},{"type":"mobile","number":"123 456-7890"}],"children":[],"spouse":null};
I want to access the phoneNumbers field
So I use
phone=obj.phoneNumbers;
I get an array but without "phoneNumbers" field.I want to get someting like this:
{
"phoneNumbers": [
{
"type": "home",
"number": "212 555-1234"
},
{
"type": "office",
"number": "646 555-4567"
},
{
"type": "mobile",
"number": "123 456-7890"
}
]
}
You have to create a new object then
var phone = { "phoneNumbers": obj.phoneNumbers };
You can add that part in:
var phone = {"phoneNumbers" : obj.phoneNumbers};
Although there should be a good reason for doing this (like, need to pass it to an API that expects exactly "x"). A single-property object is about as useful as the value of its single property.
How about making a function and using it for other similar purposes:
function transform (prop, payload) {
return { [prop]: payload };
}
And use it like:
phone = transform('phoneNumbers', obj.phoneNumbers);

Deep picking using Underscore.JS

I am trying to use underscoreJs to manipulate a JavaScript object and having problems doing so.
Here is my example
var data = {
"label": "SomeName",
"parent": [{
"id": "parentId",
"resources": [{
"name": "ID1NAME",
"calls": [
"user_get", "user2_post", "user3_delete"
]
}, {
"name": "ID2",
"calls": [
"employee1_get", "employee2_delete", "employee3_update"
]
}]
}]
};
var res = _(data).chain().
pluck('parent').
flatten().
findWhere(function(item){
item === "user_get"
}).
value();
console.log(res);
Using an element which is a part of data.parent.calls[] (example : "user_get") I would like to extract its parent object, i.e. data.parent[0].
I tried above but always get undefined. I appreciate any help on this.
One of the problems you're having is your use of _.pluck. If you execute _.pluck over an object, it'll go over the keys of the object trying to retrieve the property you specified as the second argument (in this case, 'parent'). 'label' is a string and 'parent' is an array so thus the array that you get as a result is [undefined, undefined]. The rest will then go wrong.
One solution could be as follows:
function findCallIndexInParent(call, parent) {
return _.chain(parent)
.pluck('resources')
.flatten()
.findIndex(function (obj) {
return _.contains(obj.calls, call);
})
.value();
}
function findCall(call, data) {
var parent = data.parent;
return parent[findCallIndexInParent(call, parent)];
}
console.log(findCall('user_get', data));
findCall is just a convenient method that will pass the parent property of data to findCallIndexInParent (that will retrieve the index where call is) and return the desired object with the parent array.
Lodash (a fork of underscore) provides a method to get the property of an object that would have come really handy in here (sadly, underscore doesn't have it).
The explanation of findCallIndexInParent is as follows:
Chain the parent list
pluck the resources array
As pluck maps, it returns a list of lists so a flatten is needed.
Find the index of the element which calls contains call
Return the value (the index) of the object that contains call within parent.
Here's the fiddle. Hope it helps.
This would seem to do the trick.
function findByCall(data, call) {
return _.find(data.parent, function(parent) { //From data.parent list, find an item that
return _.some(parent.resources, function(resource) {//has such parent.resource that it
return _.includes(resource.calls, call); //includes the searched resource.calls item
});
});
}
//Test
var data = {
"label": "SomeName",
"parent": [{
"id": "parentId",
"resources": [{
"name": "ID1NAME",
"calls": [
"user_get", "user2_post", "user3_delete"
]
}, {
"name": "ID2",
"calls": [
"employee1_get", "employee2_delete", "employee3_update"
]
}]
}]
};
console.log(findByCall(data, 'user_get'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>
If I understand correctly, you want to get the index of the element in the parent array which has any resource with the specified call.
data = {
"label": "SomeName",
"parent": [{
"id": "parentId",
"resources": [{
"name": "ID1NAME",
"calls": [
"user_get", "user2_post", "user3_delete"
]
}, {
"name": "ID2",
"calls": [
"employee1_get", "employee2_delete", "employee3_update"
]
}]
}]
}
// find the index of a parent
const index = _.findIndex(data.parent, parent =>
// that has any (some) resources
_.some(parent.resources, resource =>
// that contains 'user_get' call in its calls list
_.contains(resource.calls, 'user_get')
)
)
console.log(index) // 0
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
If you want to find the actual parent object, use find instead of findIndex
If you want to find all parent objects matching this call, use filter instead of findIndex

Loop over JSON items whether JSON object has multiple arrays or not

I have a working version of a function to loop through a single array in a JSON object, e.g.
[{
"Name": "John",
"Surname": "Johnson"
}, {
"Name": "Peter",
"Surname": "Johnson"
}]
sample function:
function FindName(NameToFind, data1) {
objData = JSON.parse(data1);
for (var i = 0; i < objData.length; i++) {
var Name = objData[i].Name;
if (Name == NameToFind) {
alert("found!");
}
}
}
Now I need to change this function to allow for either single OR multiple arrays e.g.
{
"Table1": [{
"Name": "John",
"Surname": "Johnson"
}, {
"Name": "Peter",
"Surname": "Johnson"
}],
"Table2": [{
"Name": "Sarah",
"Surname": "Parker"
},
{
"Name": "Jonah",
"Surname": "Hill"
}
]
}
Is there a way to determine whether the object has 1 array (like in first example) or more than one arrays (like in 2nd example), and any advice/guidance on how to extend the function to be able to loop through all the items whether it has 1 array or multiple arrays?
Your first object is an array, the second one isn't.
You can test if your argument is an array, or even just test
if (objData[0]) // that's an array
EDIT :
if you want to iterate over all properties of a (just json decoded) object, when it's not an array, you can do this :
for (var key in objData) {
var value = objData[key];
// now use the key and the value
// for example key = "Table1"
// and value = [{"Name":"John","Surname":"Johnson"}, ... ]
}

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