Title: Using Reselect Selector with Parameters
In this blog post, we will discuss how to use the reselect library to create selectors with parameters in your Redux application. Selectors are an important part of the Redux architecture as they allow you to derive computed data from your store’s state in a memoized and efficient manner. However, reselect does not natively support passing additional parameters to selectors. We will explore different approaches to overcome this limitation and create selectors that can accept custom parameters.
Approach 1: Updating Reselect 4.1
If you are using Reselect 4.1 or newer, you can take advantage of a new feature that allows selectors to accept additional parameters. You can define your selector using the createSelector function and pass an array of input selectors, followed by a function that receives the selected values and additional parameters. Let’s see an example:
// selector.js
const selectItemsByCategory = createSelector(
[
state => state.items,
(state, category) => category
],
(items, category) => items.filter(item => item.category === category)
);
// Usage in App.js
const items = selectItemsByCategory(state, 'javascript');
This approach allows you to pass custom parameters to your selector, such as a category, and filter the items based on that parameter. It provides a clean and efficient solution.
Approach 2: Creating a Higher-Order Selector
If you are using an older version of Reselect or prefer a different approach, you can create a higher-order selector that accepts a custom parameter and returns a new selector. This can be achieved by returning a function from your selector that takes the parameter as an argument. Here’s an example:
// selector.js
export const selectWithValue = (customParameter) => createSelector(
selectAllDataFiltered,
(data) => {
console.log(customParameter);
return data[customParameter];
}
);
// Usage in App.js
const data = selectWithValue('myValue')(myState);
In this approach, we create a higher-order selector called selectWithValue that takes a custom parameter and returns a new selector. This allows us to dynamically access values from our filtered data based on the custom parameter passed.
Conclusion
In this blog post, we explored different approaches to overcoming the limitation of passing additional parameters to selectors in the reselect library. We discussed using the new feature introduced in Reselect 4.1 that allows selectors to accept additional arguments. Additionally, we explored the concept of creating higher-order selectors that return functions accepting custom parameters. Both approaches provide flexible solutions for creating selectors with parameters, allowing you to compute derived data efficiently in your Redux applications.
Do you have any experience using reselect selectors with parameters? Share your thoughts and insights in the comments below!
