CA2023Reliability Enabled by default: As warning

Invalid braces in message template

Description

Logging message templates use curly braces { and } to denote named placeholders for values. Invalid brace usage in message templates can result in runtime exceptions or unexpected logging behavior. This rule detects:

Unmatched opening or closing braces.
Nested braces that aren't properly escaped.
Other malformed brace patterns.

Cause

The braces present in the message template are invalid. Ensure any braces in the message template are valid opening/closing braces, or are escaped.

How to fix violations

To fix a violation of this rule:

Ensure all opening braces { have a corresponding closing brace }.
Escape literal braces by doubling them: {{ for { and }} for }.
Fix any nested or malformed brace patterns.

Example

using Microsoft.Extensions.Logging;

class Example
{
    private readonly ILogger _logger;

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

    public void LogData(string name, int value)
    {
        // Violation: unmatched opening brace.
        _logger.LogInformation("Processing {Name with value {Value}", name, value);

        // Violation: unmatched closing brace.
        _logger.LogInformation("Processing Name} with value {Value}", name, value);
    }
}

using Microsoft.Extensions.Logging;

class Example
{
    private readonly ILogger _logger;

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

    public void LogData(string name, int value)
    {
        // Fixed: proper braces.
        _logger.LogInformation("Processing {Name} with value {Value}", name, value);

        // Fixed: escaped literal braces.
        _logger.LogInformation("Processing {{Name}} with value {Value}", name, value);
    }
}

When to suppress

Don't suppress a warning from this rule. Invalid braces in message templates can cause runtime exceptions or incorrect log output.

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