Need help on a problem with Rxjs join.
I have two observables with common id, I want to perform join to show records
from both objects based on id.
let emp = of([
{ id: 1, name: 'aa', age: 20 },
{ id: 2, name: 'bb', age: 21 },
{ id: 3, name: 'cc', age: 22 },
{ id: 4, name: 'dd', age: 23 }
]);
let details = of([
{ id: 1, address: 'ee' },
{ id: 1, address: 'ff' },
{ id: 2, address: 'gg' },
{ id: 2, address: 'hh' }
]);
I need the join like this:
[
{id: 1, name: 'aa', age: 20, details: [{address: 'ee'},{address: 'ff'}] },
{id: 2, name: 'bb', age: 21, details: [{address: 'gg'},{address: 'hh'}] },
{id: 3, name: 'cc', age: 22, details: undefined },
{id: 4, name: 'dd', age: 23, details: undefined },
]
I have tried like this:
forkJoin([emp, details]).pipe(
map(([_emp, _details]) =>
_emp.map((item) => {
return ( {
...item,
details: _details.find((item1) => {
return item1.id === item.id
})
})
})
)
).subscribe(console.log)
I got the result:
[
{id: 1, name: 'aa', age: 20, details: [{address: 'ee'}] }, // {address: 'ff'} missing
{id: 2, name: 'bb', age: 21, details: [{address: 'gg'}] }, // {address: 'hh'} missing
{id: 3, name: 'cc', age: 22, details: undefined },
{id: 4, name: 'dd', age: 23, details: undefined },
]
In this result second address is missing for id 1 and 2.
Instead of [{address: ‘ee’},{address: ‘ff’}], I got only first match [{address: ‘ee’}] for id 1.
Instead of [{address: ‘gg’},{address: ‘hh’}], I got only first match [{address: ‘gg’}] for id 2.
Please help me to accomplish the desired result
>Solution :
I think you should use filter() instead of find(). The find() operator returns only the first match.
forkJoin([emp, details]).pipe(
map(([_emp, _details]) =>
_emp.map((item) => {
return ({
...item,
// This is the line you have to modify:
details: _details.filter((item1) => item1.id === item.id)
})
})
)
).subscribe(console.log)