Table of Contents

TRLS016: Error message should not be empty

Cause

Creating an Error using factory methods like Error.Validation(), Error.NotFound(), etc. with an empty or whitespace-only message.

Rule Description

Error messages provide crucial context for:

  • Debugging: Understanding what went wrong
  • User feedback: Showing meaningful messages to users
  • Logging: Recording actionable information
  • API responses: Returning helpful error details

Empty error messages make it impossible to understand failures without diving into the code.

How to Fix Violations

Provide a meaningful message that describes the error:

// ❌ Bad - Empty message
Error.Validation("");
Error.Validation("   ");
Error.NotFound(string.Empty);

// ✅ Good - Meaningful message
Error.Validation("Email address is required", "email");
Error.Validation("Password must be at least 8 characters", "password");
Error.NotFound("Customer not found");

Examples

Example 1: Validation Error

// ❌ Bad
public static Result<Email> TryCreate(string value)
{
    if (string.IsNullOrWhiteSpace(value))
        return Error.Validation("");  // What's the error?
    // ...
}

// ✅ Good
public static Result<Email> TryCreate(string value)
{
    if (string.IsNullOrWhiteSpace(value))
        return Error.Validation("Email address is required", "email");
    // ...
}

Example 2: Not Found Error

// ❌ Bad
public async Task<Result<Customer>> GetCustomerAsync(Guid id)
{
    var customer = await _repository.FindAsync(id);
    if (customer is null)
        return Error.NotFound("");  // What wasn't found?

    return customer;
}

// ✅ Good
public async Task<Result<Customer>> GetCustomerAsync(Guid id)
{
    var customer = await _repository.FindAsync(id);
    if (customer is null)
        return Error.NotFound($"Customer with ID {id} not found");

    return customer;
}

Example 3: Multiple Validation Errors

// ❌ Bad
var errors = new List<Error>();
if (string.IsNullOrEmpty(firstName))
    errors.Add(Error.Validation(""));  // Which field?
if (string.IsNullOrEmpty(lastName))
    errors.Add(Error.Validation(""));  // Same empty message!

// ✅ Good
var errors = new List<Error>();
if (string.IsNullOrEmpty(firstName))
    errors.Add(Error.Validation("First name is required", "firstName"));
if (string.IsNullOrEmpty(lastName))
    errors.Add(Error.Validation("Last name is required", "lastName"));

Best Practices for Error Messages

  1. Be specific: "Email must contain @" not "Invalid email"
  2. Include field names: Use the fieldName parameter for validation errors
  3. Be user-friendly: Messages may be shown to end users
  4. Avoid technical jargon: "Invalid format" not "Regex match failed"
  5. Include relevant values (but not sensitive data): "Order {orderId} not found"
  • TRLS010 - Use specific error type instead of base Error class

See Also

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