CA2253: Named placeholders should not be numeric values

Property	Value
Rule ID	CA2253
Title	Named placeholders should not be numeric values
Category	Usage
Fix is breaking or non-breaking	Non-breaking
Enabled by default in .NET 10	As suggestion
Applicable languages	C# and Visual Basic

Cause

A message placeholder consists of numeric characters only.

Rule description

Named placeholders in the logging message template should not be composed of only numeric characters.

How to fix violations

Rename the numeric placeholder.

For usage examples, see the LoggerExtensions.LogInformation method.

Example

public class UserService
{
    private readonly ILogger<UserService> _logger;

    public UserService(ILogger<UserService> logger)
    {
        _logger = logger;
    }

    public void Add(string firstName, string lastName)
    {
        // This code violates the rule.
        _logger.LogInformation("Adding user with first name {0} and last name {1}", firstName, lastName);

        // This code satisfies the rule.
        _logger.LogInformation("Adding user with first name {FirstName} and last name {LastName}", firstName, lastName);

        // ...
    }
}

When to suppress errors

Do not suppress a warning from this rule.

See also

• Usage warnings