ASP.NET Core: Programmatically Set the Resource File for Localized Views

Discover how to programmatically change the resource file for localized views in `ASP.NET Core` and enhance your application’s flexibility.
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How to Programmatically Set the Resource File for Localized Views in ASP.NET Core

Localization in web applications is essential for delivering a tailored experience to users from different linguistic backgrounds. When using ASP.NET Core, you might need to switch localization resources based on certain conditions dynamically. This guide will help you understand how to programmatically set the resource file for localized views in ASP.NET Core.

Understanding the Problem

In an ASP.NET Core application, localized views are often utilized to present content in various languages. Typically, this is achieved through resource files that contain localized strings. By default, these strings are loaded from a specific folder specified in the LocalizationOptions.ResourcesPath setting. However, there might be scenarios where you need to render views using different resource files during runtime. This could be required for displaying context-specific information without altering the view files themselves.

For example, you may have a method in your controller designed to switch between two different resource files based on user input. The challenge lies in how you can accomplish this switch without altering the inherent design of your views.

Proposed Solution

To seamlessly switch between resource files at runtime, we can create a custom localization strategy. Below, you will find detailed steps on implementing this solution.

Step 1: Create a Custom View Localizer

We need to create a custom IViewLocalizer implementation that checks for an active localizer. This active localizer can be set based on a request feature available through HttpContext. Here’s a sample implementation:

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This implementation allows recognition of an active localizer based on HTTP context features.

Step 2: Define Extensions for Custom Factory

You need to create factories to handle resource paths dynamically. One way to achieve this is by extending HtmlLocalizerFactory. Below is a relevant code snippet for such an extension:

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

This extension allows setting the resources path at runtime.

Step 3: Create Custom Resource Manager Factory

Since ASP.NET Core uses ResourceManager internally, you need a factory that customizes the cache key based on the resource path. Here’s a skeleton for the factory:

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

Step 4: Register Custom Services

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Using the Localizer in Controllers

To apply the localizer dynamically based on conditions, use the following code in your controller action method:

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

Important Note

Be aware that invoking UseLocalizer within a controller's or page model's scope may introduce performance overhead due to excessive view discovery logic. Thus, whenever feasible, you should call it directly inside your Razor views or pages.

Conclusion

By following the steps outlined above, you can flexibly switch between different resource files for localization in your ASP.NET Core applications. This capability allows for a more customized user experience and opens up new possibilities for dynamic content delivery based on context.

Now you are equipped to implement this feature, ensuring that your web applications remain adaptable and responsive to user needs.