I am learning RxJS library, I am getting array of object from backend, I want to filter it using RxJS.
I tried this:
.pipe(
map(dataArray => from(dataArray).pipe(
map(dataObject => {
filter(dataObject.Code === 'ABC' || dataObject.Code === 'XYZ')
}
))
)
but it is not working, getting lots of syntax error
RxJS filter operator is != Javascript's Array#filter function.
The former is used to filter out emissions from the observable based on a condition.
To filter out specific elements of an array, you'd need to use JS Array#filter. But you were right initially to go with the map operator to transform the incoming emission.
Try the following
someObservable$.pipe(
map((dataArray: any[]) =>
dataArray.filter((dataObject: any) =>
dataObject.Code === 'ABC' || dataObject.Code === 'XYZ'
)
)
).subscribe(
...
);
someObservable$ in the post emits every 5 seconds, and you wish to get only the emissions that pass some criteria, then you'd use the RxJS filter pipe. The filtering that you actually need in your context is to filter a specific array. Then you'd go with JS array filtering methods. There is no need for RxJS there.Update the response is error: filter is to filter the whole object, not to filter an array
from(dataArray).pipe(
filter(dataObject=>dataObject.Code === 'ABC' || dataObject.Code === 'XYZ')
)
NOTE, In your code you use pipe map pipe map... you can use pipe(rxjsoperator1,rxjsoperator2,rxjsoperator3,...)
some like:
.pipe(
map(dataArray => from(dataArray),
map(dataObject=>....),
tap(res=>{console.log(res)}),
filter(dataObject=>dataObject.Code === 'ABC' || dataObject.Code === 'XYZ')
)
