Скачать или смотреть How to Create a Razor Component with Two-Way Binding in Blazor

Learn how to create a Razor component in Blazor that supports `two-way data binding`, enabling seamless interaction between parent and child components.
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This video is based on the question https://stackoverflow.com/q/70785291/ asked by the user 'Flippowitsch' ( https://stackoverflow.com/u/6038249/ ) and on the answer https://stackoverflow.com/a/70786003/ provided by the user 'enet' ( https://stackoverflow.com/u/6152891/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Creating a Razor Component with Two-Way Binding in Blazor

When working with Blazor, you might face challenges while trying to create reusable components that maintain data consistency between the parent and child components. One common scenario is implementing two-way data binding. In this post, we will explore how to create a customized input component utilizing Blazor’s powerful binding features.

Understanding the Problem

You may have created a customized input component, but how do you ensure that the changes in the child component are reflected back to the parent? The issue at hand is getting two-way data binding to work in a Razor component.

Let’s break down the situation:

You created a simple input component with a label and received input values.

However, when employing this component multiple times, the bindings lead to only one-direction updates.

This limitation can be easily resolved with a few modifications.

The Solution: Implementing Two-Way Data Binding

To achieve two-way data binding between your parent and child components, you need to set up an additional parameter in your child component that can communicate value changes back to the parent. Here’s a step-by-step guide on how to do it.

Step 1: Define a Value Property in Your Parent Component

In your parent component, you must create a property that holds the value you want to bind.

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Step 2: Create Parameters in the Child Component

In the child component, you must define:

A property for the bound value.

An event callback to notify the parent of any changes.

Here's how you can define these parameters:

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Step 3: Update the Child Component's Input

Within your child component's markup, bind the input’s value and set up an event handler to invoke the callback when the value changes:

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Step 4: Use the Child Component in the Parent

Now, you can utilize the child component in the parent component while binding the value:

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Step 5: Updating the Property Names

If you prefer to keep the parameter names distinct, you can rename them accordingly. If your child parameter is BindValue, then the event callback should be BindValueChanged:

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Use it in the parent component like this:

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This change will ensure that your parent component’s property remains in sync with the input in the child component.

Testing the Solution

After implementing these changes, you should now be able to see updates reflecting both in the input component and the parent component. Test the implementation by adjusting the value in the child component and confirming that the changes reflect in your parent component seamlessly.

Conclusion

Creating reusable Razor components with effective data binding can significantly enhance your Blazor applications. By following these steps, you can set up a robust two-way data binding mechanism that facilitates smooth interactions.

Now that you have an understanding of how to implement this feature, feel free to experiment and adapt the example to fit your own needs. Happy coding!