CODEWITHSUNDEEP
angularselectrxjspipestore
Islam Murtazaev
Islam Murtazaev

Reputation: 1778

Why should I use select with pipe in Angular subscribe?

I was reading the docs of angular and its use of RxJS library. And I found this info

Pipes

You can use pipes to link operators together. Pipes let you combine multiple functions into a single function. The pipe() function takes as its arguments the functions you want to combine, and returns a new function that, when executed, runs the composed functions in sequence.

So the purpose of piping is to chain multiple functions, but what made me curious is that I have seen many times the use of pipe with only one function inside, eg:

this.itemSubscription = this.store
            .pipe(select(state => state.items.root))
            .subscribe(state => {
                this.items = state.items;
            });

When I try to use select without pipe, then my tslint says:

select is deprecated: from 6.1.0. Use the pipeable select operator instead. (deprecation)tslint(1)

Why is that happening? Am I missing something? Could not find any relevant explanation on the Internet.

Upvotes: 2

Views: 4010

Answers (3)

Stavm
Stavm

Reputation: 8121

You are mixing things.

select is deprecated: from 6.1.0. Use the pipeable select operator instead. (deprecation)tslint(1)

refers to the use of select outside of the pipe.

this.store.select( ... )

using select inside a pipe is the way to go.

import { Store, select } from '@ngrx/store';

this.store.pipe(select( ... ))

is perfectly fine.

Upvotes: 1

Jayme
Jayme

Reputation: 1946

Pipe was introduced to RxJS in v5.5 to take code that looked like this:

of(1,2,3).map(x => x + 1).filter(x => x > 2);

and turn it into this

of(1,2,3).pipe(
  map(x => x + 1),
  filter(x => x > 2)
);

Same output, same concept but with different syntax.

It cleans up the 'observable.prototype' and makes the RxJS library more tree-shakeable, you only need to import what you use. It also makes it easier to write and use third-party operators.

Upvotes: 5

user3588429
user3588429

Reputation: 1016

It´s considered best practice to use lettable operators. Because you can only import the specific operators you need into your project. The rest can be removed by tree shaking and so the bundle size is decreasing.

It seems a little bit weird in the beginning to use pipe with just one operator but you will get used to it.

Upvotes: 2

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