Compatibility of CreateEntityAdapter and Normalizr in Redux Toolkit

Описание: Discover how to effectively integrate `CreateEntityAdapter` with `Normalizr` in your Redux store to avoid issues with undefined SelectId.
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This video is based on the question https://stackoverflow.com/q/68975356/ asked by the user 'Ed Campion' ( https://stackoverflow.com/u/1401929/ ) and on the answer https://stackoverflow.com/a/68977125/ provided by the user 'markerikson' ( https://stackoverflow.com/u/62937/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Compatibility of CreateEntityAdapter and Normalizr in Redux Toolkit

When developing applications with Redux Toolkit, integrating normalized data can sometimes lead to unexpected challenges. One such issue arises when using CreateEntityAdapter in conjunction with Normalizr. You may encounter a situation where the SelectId function always returns undefined, causing your actions to fail. In this guide, we will explore the problem in detail and provide a step-by-step guide on how to resolve it.

The Problem: SelectId Always Undefined

As you try to add normalized records from normalizr.normalize to your Redux store using createEntityAdapter, it's not uncommon to run into a frustrating problem. You dispatch your action, but instead of successfully updating the state, it fails because the default SelectId function returns undefined. This can halt your progress and leave you wondering about the next steps.

Here's a brief overview of what you might be experiencing:

Normalized Data Structure: Your normalized data may appear in an object format similar to this:

[[See Video to Reveal this Text or Code Snippet]]

Error Diagnosis: When you dispatch your action, you might find that the id field isn’t recognized as expected. Instead, it results in undefined, which prevents your slice from functioning properly.

The Solution: No Custom SelectId Needed (In Many Cases)

Fortunately, the good news is that createEntityAdapter assumes by default that each item in the payload has an id field. If your data structure follows this standard, then you shouldn't need to write a custom SelectId function. Here’s how it works:

1. Verify Your Data Structure

Before diving into custom solutions, ensure that your normalized data includes an id field. The createEntityAdapter works seamlessly with records that adhere to this format. If your data looks like the example provided earlier, you may be all set.

2. Default Functionality

By default, createEntityAdapter utilizes the id field for its operations, meaning that if the id is present and correctly mapped in the data, state updates should occur without error. Thus, check the following:

Confirm that every item in your normalized structure contains a unique id field.

Ensure that your normalized payload is being dispatched correctly into the store.

3. When to Write a Custom SelectId Function

While it’s not typically necessary if your structure adheres to the id field requirement, there are situations where you might consider writing a custom SelectId function. This might be the case if:

Your data uses a different identifier field instead of id. In this situation, you can define custom logic for id selection.

There are specific properties that uniquely identify your records that aren't equipped with a consistent identifier across all data.

Example of a Custom SelectId Implementation

If you find yourself in a scenario that requires a custom SelectId, here's a simple outline to implement it:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Integrating CreateEntityAdapter with Normalizr can be straightforward if you ensure that your data structure is compatible, notably by confirming the presence of an id field. In most cases, you won't need a custom SelectId function. However, being aware of exceptions is crucial, so you can address any issues promptly when they arise.

With a clear understanding of these concepts, you can confidently manage your Redux state while working with normalized data, making your app development smoother and more efficient.