Managing Multiple Entity and Not Entity States in Angular's NgRx

Discover how to efficiently manage multiple states in Angular's NgRx using effective selectors, effects, and the facade pattern in Angular 9.
---
This video is based on the question https://stackoverflow.com/q/62291773/ asked by the user 'Miguel Moura' ( https://stackoverflow.com/u/577805/ ) and on the answer https://stackoverflow.com/a/62292255/ provided by the user 'Nosheep' ( https://stackoverflow.com/u/10050648/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Multiple entity and not entity states in Angular's NgRx?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Navigating Multiple Entity and Non-Entity States in Angular's NgRx

In the world of Angular development, particularly when using NgRx for state management, understanding how to efficiently manage multiple states can be challenging. This is especially true when your component needs to display various data such as recent posts, top posts, tags, and handle search queries. In this guide, we will explore an effective strategy for structuring and managing these states in Angular 9 using NgRx.

Understanding the Problem

Consider a component that requires the following:

A list of recent posts.

A list of top posts.

A list of tags.

A mechanism to hold a search query string.

With these requirements, it raises several important questions regarding state management in NgRx:

Should you create multiple states for each of these requirements (Recent Posts, Top Posts, Tags, Query String)?

Is it necessary to have two separate Post States for Recent and Top posts if the only difference is in how they are loaded from the database?

How can you effectively encapsulate all these states within a single component state?

Solutions Breakdown

1. Single State with Selectors

Instead of creating multiple states for each requirement, it is recommended to maintain one overarching state. This single state can then be sliced using selectors to extract needed data, effectively simplifying your state management process. Specifically:

Create a single PostState interface that extends EntityState<Post>.

Use selectors to derive subsets of the post data as needed for recent, top posts, and any other required attributes.

This approach minimizes redundancy and keeps your state logic straightforward. For instance, you might have four selectors like so:

selectRecentPosts

selectTopPosts

selectTags

selectQueryString

2. Utilizing Effects for Data Loading

Managing side effects is an essential part of any Angular application involving data fetching. When dealing with server interactions, such as loading recent or top posts, use NgRx Effects. This separates the state management logic from your component logic, leading to cleaner code. Here’s how it works:

Define effects in your application to handle the data fetching processes for recent and top posts.

Utilize actions to trigger these effects, which in turn will update the single PostState based on the response from the server.

3. Implementing a Facade Pattern

To prevent your component from taking on too many responsibilities (essentially becoming a "jack of all trades"), you can implement a Facade pattern. This abstraction layer functions as a mediator between your component and the NgRx store. Here’s how to structure it:

Facade Creation: Create a service (facade) that exposes methods for data retrieval and action dispatching.

Using Observables: Inside the facade, use RxJS observables to provide the required slices of state and listen to state changes.

Action Dispatching: The component can call methods from the facade to dispatch actions (e.g., fetch posts) without directly interacting with the store.

This keeps your component succinct and focused only on displaying data rather than handling all the complexities of state management.

Conclusion

In summary, managing multiple entity and non-entity states in Angular's NgRx can be effectively approached by leveraging a single comprehensive state, employing selectors for data access, utilizing effects for handling server interactions, and implementing a facade to streamline component interactions. By following these best practices, you can create a well-structured and maintainable Angular application.

With this structured methodology, you can simplify your development process while ensuring that yo

Видео Managing Multiple Entity and Not Entity States in Angular's NgRx канала vlogize