Develop Reference

Loop through the keys a Type in Typescript and remove the ones which have the value as undefined

I have a Type described in typescript like this -
export type User = {
name: string;
username: string;
phoneNumber: string;
personalEmail?: string;
workEmail?: string
}
I'm fetching some data from a json file which consists of objects like these and shaping the data to this type User for each object with this function
const shaper = (obj: any): User {
const user: User = {
name: obj.name,
username: obj.username,
number: obj.number,
personalEmail: obj.personalEmail,
workEmail: obj.workEmail,
}
// remove from user the fields which have value === undefined
return user;
}
In the shaper function, I want to remove the fields of the variable user which have the value as undefined (eg : obj.personalEmail does not exist)
How do I achieve this?

Here you have a working example.
You can use delete obj[key]
const shaper = (obj) => {
const user = {
name: obj.name,
username: obj.username,
number: obj.number,
personalEmail: obj.personalEmail,
workEmail: obj.workEmail,
}
Object.entries(user).forEach(([key, value]) => {
if (value === undefined) {
delete user[key];
console.log("deleted", key);
}
});
return user;
}
const shapedResult = shaper({
name: "foo",
workEmail: "bar#bar.com"
});
console.log(shapedResult);

You could do something like this:
/* Test Data */
const test = {
name: 'name',
username: 'username',
needToRename: '123456789',
another: 'blah',
something: 'else',
workEmail: 'hello#example.com'
}
/* Example 1 */
const shaper = ({name, username, needToRename:phoneNumber, personalEmail, workEmail}) => {
return {
name,
username,
phoneNumber,
...( personalEmail !== undefined && {personalEmail} ),
...( workEmail !== undefined && {workEmail})
}
}
console.log(shaper(test));
Or you could extract the undefined check into a helper function and do this:
/* Test Data */
const test = {
name: 'name',
username: 'username',
needToRename: '123456789',
another: 'blah',
something: 'else',
workEmail: 'hello#example.com'
}
/* Example 2 */
function undefinedHelper(name, obj) {
return obj[name] === undefined ? {} : {[name]: obj[name]};
}
const shaper2 = (obj) => {
return {
name: obj.name,
username: obj.username,
phoneNumber: obj.needToRename,
...undefinedHelper('personalEmail', obj),
...undefinedHelper('workEmail', obj)
}
}
console.log(shaper2(test));
This answer was helpful: https://stackoverflow.com/a/40560953/2344607

Jascript removes value of Joi class

I'm using Typescript and have this, I'm trying to create Joi validation object.
Example input :
{
key: 'name',
validate: Joi.required().options({
language: {
any: {
required: 'is required'
},
string: {
min: 'must be at least 3 Characters'
},
},
}),
}
And a method :
getObjects(inputs: Array<Input>) {
const newObject = {};
inputs.forEach(input => {
newObject[input.key] = input.validate;
});
return newObject;
}
But when checking newObject, it's only keys, and validation is undefined.
I realise this has something to do with the loop because this works.
newObject[inputs[0].key] = inputs[0].validate;
newObject[inputs[1].key] = inputs[1].validate;

Change an object value inside a loop in JavaScript

I have an array of objects like this:
const data = [{
_id:"49847444033",
name:"yoko"
},{
_id:"49847433333",
name:"doira"
}]
I have to change each item name property to something like this :
...
{
_id:"49847433333",
name:{
en:"John"
}
}
My attempt is to loop object like following :
data.forEach((item) => {
item.name = {en:"john"}
console.log(item)
})
But this always console the original item and the name property value is not modified.

const newData = data.map(user => ({ _id: user._id, name: { en: user.name } }))

I created a library to express transformations like this very simply.
const { pipe, fork, get } = require('rubico')
const data =
[ { _id: '49847444033', name: 'yoko'}
, { _id: '49847433333', name: 'doira'}
]
const onData = pipe([
fork({
_id: get('_id'), // data => data._id
name: fork({ en: get('name') }), // data => ({ en: data.name })
}),
console.log,
])
data.map(onData) /*
{ _id: '49847444033', name: { en: 'yoko' } }
{ _id: '49847433333', name: { en: 'doira' } }
*/
I've commented the code above, but to really understand rubico and get started using it, I recommend you read the intuition and then the docs

try somthing like:
const newList = data.map(obj => {
return { _id: obj._id, name: { en: obj.name } }
});
and the newList list is your new data list so you can do it:
data = newList;
EDIT:
if you have more properties you can change the return line to:
return { ...obj, name: { en: obj.name } }
what will happen here, it will deploy all the object properties as they are, and modify the name property, unfortunately, every property you want to modify, you have to re-write it.

Flow: Require that polymorphic type has property

I'm trying to correctly type a function that uses Flow generic (or polymorphic) types to paginate an array of objects into a graphql/Relay-style "page" object.
Here's a simplified example:
type DBNode = {
uid: string
}
type Student = DBNode & {
username: string
}
const students = [{
uid: '123',
username: 'user-one',
}, {
uid: '345',
username: 'user-two',
}]
type Classroom = DBNode & {
room: number
}
const classrooms = [{
uid: '234',
room: 666,
}, {
uid: '456',
room: 667,
}]
type Edge<T> = {
cursor: string,
node: T
}
const itemToEdge = <T>(item: T): Edge<T> => ({
cursor: item.uid,
node: item
})
type Page<T> = {
pageInfo: {
count: number,
},
edges: Array<Edge<T>>
}
const assemblePage = <T>(items: Array<T>): Page<T> => ({
pageInfo: {
count: items.length,
},
edges: items.map(itemToEdge)
})
const studentPage = (): Page<Student> => {
return assemblePage(students)
}
const classroomPage = (): Page<Classroom> => {
return assemblePage(classrooms)
}
The error I receive is:
cursor: item.uid,
^ Cannot get `item.uid` because property `uid` is missing in `T` [1].
References:
34: const itemToEdge = <T>(item: T): Edge<T> => ({
^ [1]
Is there a to ensure that the polymorphic type T is always an object that has a uid field?
Alternatively, I tried typing assemblePage and itemToEdge to require that the item(s) are of a DBNode type, which results in:
38: node: item ^ Cannot return object literal because `DBNode` [1] is incompatible with `T` [2] in property `node`.
References:
35: const itemToEdge = <T>(item: DBNode): Edge<T> => ({
^ [1]
31: node: T ^ [2]
Demo
Edit: Here's a working version of the demo, thanks #Aleksey L for the help!
Working Demo

You can define constraint to generic type parameter:
const itemToEdge = <T: DBNode>(item: T): Edge<T> => ({
cursor: item.uid,
node: item
})
const assemblePage = <T: DBNode>(items: Array<T>): Page<T> => ({
...
})
From docs:
Generics allow you to hold onto the more specific type while adding a constraint

Verify if content key Json has exist using Vue

I want to know how to check if "novalue" exist
For example:
{
name: "maria",
city_id: "novalue"
....
}
How i do this in Vue?
Do it in <div v-if="condition"> or function?

In case you want to/can use ES7 features:
const containsKey = (obj, key ) => Object.keys(obj).includes(key);
Implementation example:
const someCoolObject = {name: 'Foo', lastName: 'Bar'};
const hasName = containsKey(someCoolObject, 'name');
const hasNickName = containsKey(someCoolObject, 'hasNickName');
console.log(hasName, hasNickName); // true, false
For Vue:
Component:
{
methods: {
containsKey(obj, key ) {
return Object.keys(obj).includes(key);
}
},
computed: {
hasName() {
return this.containsKey(this.someObject, 'name');
}
}
}
Template:
<div v-if="hasName"></div>