Angular - The filter method cannot be used on Observables

I have a database with users who need to complete unique homework sessions. Each homework session has its own identifier, name, date, and other details.

After fetching all the user's homework from the database, it is stored in a private variable called 

userHomework: Observable<any>
. I want to be able to search for a specific homework by name that the user inputs.

To achieve this, I am using the following function:

this.userHomework = this.userHomework.map(allHomework => 
    allHomework.filter(homeworkSession =>
 homeworkSession.name.toLowerCase().includes(this.userInput.toLowerCase())));

Unfortunately, when I run this function, I encounter the error message: 

allHomework.filter is not a function
.

I have attempted importing the filter method in two different ways:

import 'rxjs/add/operator/filter';

and

import { filter } from 'rxjs/operators';

However, with the second import, I also receive the warning:

[ts] 'filter' is declared but its value is never read.

Can someone please help me identify where I went wrong and how I can effectively filter my Observable?

angulartypescriptfilterrxjsobservable

Answer №1

allHomework in your situation isn't an Observable but instead an any (as you have specified) emitted by the userHomework observable. You can use the filter() function on arrays, so give this a try:

  • Verify that allHomework is actually an array
  • Define it as: 
    private userHomework: Observable<any>[]
  • Remove the filter imports from Observable

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