src/log4net/Layout/RawPropertyLayout.cs

#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using log4net.Core;
using log4net.Util;

namespace log4net.Layout;

/// <summary>
/// Extracts the value of a property from the <see cref="LoggingEvent"/>.
/// </summary>
/// <author>Nicko Cadell</author>
public class RawPropertyLayout : IRawLayout
{
  /// <summary>
  /// The name of the value to look up in the LoggingEvent Properties collection.
  /// </summary>
  public string Key { get; set; } = string.Empty;

  /// <summary>
  /// Looks up the property for <see cref="Key"/>.
  /// </summary>
  /// <param name="loggingEvent">The event to format</param>
  /// <returns>returns property value</returns>
  /// <remarks>
  /// <para>
  /// Looks up and returns the object value of the property
  /// named <see cref="Key"/>. If there is no property defined
  /// with than name then <c>null</c> will be returned.
  /// </para>
  /// </remarks>
  public virtual object? Format(LoggingEvent loggingEvent) 
    => loggingEvent.EnsureNotNull().LookupProperty(Key);
}