Use a consistent naming convention

Oct 13, 2025 by wbrum.org 103 views

Introduction

When building a web application, especially one that targets a global audience, localization is a crucial aspect to consider. In ASP.NET Web API, localization is achieved through the use of resource files, such as ErrorMessages.resx. However, sometimes you may encounter an issue where the API response returns the error key name instead of the localized message. In this article, we will explore the reasons behind this issue and provide a step-by-step guide on how to resolve it.

Understanding Localization in ASP.NET Web API

Localization in ASP.NET Web API is based on the concept of resource files. These files contain key-value pairs, where the key is the error code and the value is the localized message. The ErrorMessages.resx file is a common resource file used for storing error messages. When a localized message is required, the API uses the key to retrieve the corresponding value from the resource file.

Example of Values in ErrorMessages.resx

Here's an example of values in the ErrorMessages.resx file:

Key	Value
`OrderIsClosed`	"Can't edit closed order."
`OrderIsClosed`	"Не можна редагувати закрите замовлення."

The Issue: Getting Error Key Name Instead of Localized Message

So, what happens when the API response returns the error key name instead of the localized message? There are several reasons that could lead to this issue:

Missing Resource File: The most common reason is that the resource file is missing or not properly configured.
Incorrect Key Name: The key name in the API code does not match the key name in the resource file.
Localization Not Enabled: Localization is not enabled in the API project.
Resource File Not Loaded: The resource file is not loaded properly in the API project.

Step-by-Step Guide to Resolve the Issue

To resolve the issue, follow these steps:

Step 1: Verify the Resource File

First, verify that the resource file is present in the project and that it is properly configured. Make sure that the key name in the API code matches the key name in the resource file.

Step 2: Enable Localization

Enable localization in the API project by setting the NeutralResourcesLanguage attribute in the AssemblyInfo.cs file:

[assembly: NeutralResourcesLanguage("en-US")]

Step 3: Load the Resource File

Load the resource file in the API project by adding the following code in the WebApiConfig.cs file:

public static void Register(HttpConfiguration config)
{
    // ...
    config.Services.Add(typeof(IExceptionHandler), new CustomExceptionHandler());
    // ...
}

public class CustomExceptionHandler : IExceptionHandler
{
    public Task HandleExceptionAsync(Exception exception, CancellationToken cancellationToken)
    {
        // Load the resource file
        var resourceProvider = new ResourceManager("ErrorMessages", typeof(ErrorMessages).Assembly);
        var localizedMessage = resourceProvider.GetString(exception.Message);

        // Return the localized message
        return Task.FromResult(localizedMessage);
    }
}

Step 4: Use the Localized Message

Use the localized message in the API response by returning the result of the HandleExceptionAsync method:

public IHttpActionResult GetOrder(int id)
{
    // ...
    try
    {
        // ...
    }
    catch (Exception ex)
    {
        // Return the localized message
        return Content(HttpStatusCode.BadRequest, ex.Message);
    }
}

Conclusion

In this article, we explored the issue of getting error key name instead of localized message in API response. We discussed the reasons behind this issue and provided a step-by-step guide on how to resolve it. By following these steps, you can ensure that your API returns the correct localized message for each error code.

Best Practices

To avoid this issue in the future, follow these best practices:

Use a consistent naming convention: Use a consistent naming convention for key names in the API code and resource files.
Verify the resource file: Verify that the resource file is present in the project and that it is properly configured.
Enable localization: Enable localization in the API project by setting the NeutralResourcesLanguage attribute.
Load the resource file: Load the resource file in the API project by adding the necessary code.

Frequently Asked Questions

In this article, we will answer some of the most frequently asked questions related to getting error key name instead of localized message in API response.

Q: What is the main reason for getting error key name instead of localized message in API response?

A: The main reason for getting error key name instead of localized message in API response is that the resource file is missing or not properly configured.

Q: How can I verify that the resource file is present in the project and that it is properly configured?

A: To verify that the resource file is present in the project and that it is properly configured, follow these steps:

Check if the resource file is present in the project.
Verify that the key name in the API code matches the key name in the resource file.
Check if the resource file is properly configured by checking the NeutralResourcesLanguage attribute in the AssemblyInfo.cs file.

Q: What is the `NeutralResourcesLanguage` attribute and how does it affect localization?

A: The NeutralResourcesLanguage attribute is used to specify the neutral language for the assembly. It affects localization by determining the default language for the assembly.

Q: How can I enable localization in the API project?

A: To enable localization in the API project, follow these steps:

Set the NeutralResourcesLanguage attribute in the AssemblyInfo.cs file.
Load the resource file in the API project by adding the necessary code.

Q: What is the difference between `ResourceManager` and `ResourceProvider`?

A: ResourceManager and ResourceProvider are both used to load resource files, but they serve different purposes.

ResourceManager is used to load a specific resource file.
ResourceProvider is used to load a resource file based on the current culture.

Q: How can I use the localized message in the API response?

A: To use the localized message in the API response, follow these steps:

Load the resource file using ResourceManager or ResourceProvider.
Return the localized message in the API response.

Q: What are some best practices to avoid getting error key name instead of localized message in API response?

A: Some best practices to avoid getting error key name instead of localized message in API response include:

Use a consistent naming convention for key names in the API code and resource files.
Verify that the resource file is present in the project and that it is properly configured.
Enable localization in the API project by setting the NeutralResourcesLanguage attribute.
Load the resource file in the API project by adding the necessary code.

Conclusion

In this article, we answered some of the most frequently asked questions related to getting error key name instead of localized message in API response. We provided step-by-step guides and best practices to help you resolve this issue and ensure that your API returns the correct localized message for each error code.

Additional Resources

For more information on localization in ASP.NET Web API, refer to the following resources:

By following these best practices and resources, you can ensure that your API provides a better user experience for your global audience.