How to handle errors and exceptions in a .NET Core API?

Question

Aryan Kumar · Answer

Handling errors and exceptions in a .NET Core API is important to ensure that users have a good experience and that the API remains available. There are a few different ways to handle errors and exceptions in .NET Core APIs:

Try-catch blocks: Try-catch blocks are used to catch exceptions and handle them gracefully. The try block contains the code that is likely to throw an exception. The catch block contains the code that will be executed if an exception is thrown.
Exception filters: Exception filters are used to filter exceptions before they are handled by the try-catch block. Exception filters can be used to ignore certain exceptions or to handle exceptions differently depending on their type.
Centralized exception handling: Centralized exception handling is the practice of handling all exceptions in a single location. This can help to ensure that all exceptions are handled consistently and that errors are not logged multiple times.

The following code shows how to handle errors and exceptions in a .NET Core API using a try-catch block:

C#

public class ProductController : ControllerBase {

  [HttpGet("{id}")]
  public IActionResult Get(int id) {
    // Get the product data from the database.
    // ...

    // Try to get the product data.
    try {
      product = productRepository.GetById(id);
    } catch (Exception ex) {
      // Handle the exception.
      return BadRequest(ex.Message);
    }

    // Return the product data.
    return Ok(product);
  }
}

In this code, the Get() action method first tries to get the product data from the database. If an exception is thrown, the catch block will be executed and the error message will be returned to the user.

The following code shows how to handle errors and exceptions in a .NET Core API using an exception filter:

C#

public class ProductController : ControllerBase {

  [HttpGet("{id}")]
  public IActionResult Get(int id) {
    // Get the product data from the database.
    // ...

    // Filter the exception.
    var filter = new MyExceptionFilter();
    filter.OnException(ex, context);

    // Return the product data.
    return Ok(product);
  }
}

public class MyExceptionFilter : ExceptionFilterAttribute {

  public override void OnException(Exception ex, FilterContext context) {
    // Handle the exception.
    if (ex is BadRequestException) {
      return;
    }

    // Rethrow the exception.
    throw;
  }
}

In this code, the MyExceptionFilter exception filter is used to filter out BadRequestExceptions. Any other exceptions will be rethrown.

It is important to handle errors and exceptions gracefully in .NET Core APIs. This will help to ensure that users are not presented with cryptic error messages and that the API remains available.

Here are some additional tips for handling errors and exceptions in .NET Core APIs:

Use consistent error messages across your API. This will help users understand what went wrong and how to fix it.
Use a descriptive error code. This will help users troubleshoot the error.
Log exceptions to the application log. This will help you track down and fix errors.
Use a centralized exception handling mechanism. This will help to ensure that all exceptions are handled consistently.

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How to handle errors and exceptions in a .NET Core API?

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