Through my observable testData$ I receive data that looks like this:
[
{
type: 'userInfo',
data: [
{
username: 'Sara',
age: 27,
},
{
username: 'Max',
age: 31,
},
{
username: 'Kim',
age: 26,
},
],
},
{
type: 'cars',
data: [
{
type: 'Mercedes'
},
],
},
];
From testData$ I want to get the age of Max and store it in maxAge$. I have tried this code so far:
public maxAge$ = this.testData$.pipe(
map(x => x.filter(obj => obj.type === 'userInfo')),
map(value => value[0]),
pluck('data'),
);
It returns the data array like this:
[
{
username: 'Sara',
age: 27,
},
{
username: 'Max',
age: 31,
},
{
username: 'Kim',
age: 26,
},
]
But now I dont know how to continue from here to get the age-value of Max. It's important in this case not to select just the second array element of data because the order can vary. What can I do?
const users = [
{
username: 'Sara',
age: 27,
},
{
username: 'Max',
age: 31,
},
{
username: 'Kim',
age: 26,
},
]
cons maxage = users.find(user=>user.username=='MAX').age;
public maxAge$ = this.testData$.pipe(
map(x => x.find(obj => obj.type === 'userInfo').data),
map(users => users.find(user=>user.username==='Max').age)
);You could use the RxJS map operator with Array#find method
const testData = [{ type: 'userInfo', data: [{ username: 'Sara', age: 27, }, { username: 'Max', age: 31, }, { username: 'Kim', age: 26, }, ], }, { type: 'cars', data: [{ type: 'Mercedes' }, ], }, ];
const maxAge = testData
.find(item => item.type === 'userInfo')
.data
.find(item => item.username === 'Max')
.age;
console.log(maxAge);So the stream would look like
public maxAge$ = this.testData$.pipe(
map((testData: any) => testData
.find(item => item.type === 'userInfo')
.data
.find(item => item.username === 'Max')
.age
)
);
If you do not know if the properties would always be available (which might lead to undefined errors), you could use the optional chaining operator ?..