AppSettingLayoutRenderer2 - Added support for ConnectionStrings Lookup

src/NLog/Internal/ConfigurationManager2.cs

@@ -0,0 +1,51 @@
+// 
+// Copyright (c) 2004-2019 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without 
+// modification, are permitted provided that the following conditions 
+// are met:
+// 
+// * Redistributions of source code must retain the above copyright notice, 
+//   this list of conditions and the following disclaimer. 
+// 
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution. 
+// 
+// * Neither the name of Jaroslaw Kowalski nor the names of its 
+//   contributors may be used to endorse or promote products derived from this
+//   software without specific prior written permission. 
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 
+// THE POSSIBILITY OF SUCH DAMAGE.
+// 
+
+#if !SILVERLIGHT && !__IOS__ && !__ANDROID__ && !NETSTANDARD
+
+namespace NLog.Internal
+{
+    using System.Collections.Specialized;
+
+    internal class ConfigurationManager2 : IConfigurationManager2
+    {
+        public System.Configuration.ConnectionStringSettings LookupConnectionString(string name)
+        {
+            return System.Configuration.ConfigurationManager.ConnectionStrings[name];
+        }
+
+        public NameValueCollection AppSettings => System.Configuration.ConfigurationManager.AppSettings;
+    }
+}
+
+#endif

src/NLog/Internal/IConfigurationManager2.cs

@@ -0,0 +1,44 @@
+// 
+// Copyright (c) 2004-2019 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without 
+// modification, are permitted provided that the following conditions 
+// are met:
+// 
+// * Redistributions of source code must retain the above copyright notice, 
+//   this list of conditions and the following disclaimer. 
+// 
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution. 
+// 
+// * Neither the name of Jaroslaw Kowalski nor the names of its 
+//   contributors may be used to endorse or promote products derived from this
+//   software without specific prior written permission. 
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF 
+// THE POSSIBILITY OF SUCH DAMAGE.
+// 
+
+#if !SILVERLIGHT && !__IOS__ && !__ANDROID__ && !NETSTANDARD
+
+namespace NLog.Internal
+{
+    internal interface IConfigurationManager2 : IConfigurationManager
+    {
+        System.Configuration.ConnectionStringSettings LookupConnectionString(string name);
+    }
+}
+
+#endif

src/NLog/LayoutRenderers/AppSettingLayoutRenderer2.cs

@@ -55,6 +55,8 @@ namespace NLog.LayoutRenderers
     [ThreadSafe]
     public sealed class AppSettingLayoutRenderer2 : LayoutRenderer, IStringValueRenderer
     {
+        private string _connectionStringName = null;
+
         ///<summary>
         /// The AppSetting item-name
         ///</summary>
@@ -75,7 +77,15 @@ public sealed class AppSettingLayoutRenderer2 : LayoutRenderer, IStringValueRend
         /// <docgen category='Rendering Options' order='10' />
         public string Default { get; set; }
 
-        internal IConfigurationManager ConfigurationManager { get; set; } = new ConfigurationManager();
+        internal IConfigurationManager2 ConfigurationManager { get; set; } = new ConfigurationManager2();
+
+        /// <inheritdoc/>
+        protected override void InitializeLayoutRenderer()
+        {
+            string connectionStringSection = "ConnectionStrings.";
+            _connectionStringName = Item?.TrimStart().StartsWith(connectionStringSection, StringComparison.InvariantCultureIgnoreCase) == true ?
+                Item.TrimStart().Substring(connectionStringSection.Length) : null;
+        }
 
         /// <summary>
         /// Renders the specified application setting or default value and appends it to the specified <see cref="StringBuilder" />.
@@ -94,7 +104,9 @@ private string GetStringValue()
             if (string.IsNullOrEmpty(Item))
                 return Default;
 
-            string value = ConfigurationManager.AppSettings[Item];
+            string value = _connectionStringName != null ?
+                ConfigurationManager.LookupConnectionString(_connectionStringName)?.ConnectionString :
+                ConfigurationManager.AppSettings[Item];
             if (value == null && Default != null)
                 value = Default;
 

tests/NLog.UnitTests/LayoutRenderers/AppSettingTests.cs

@@ -35,10 +35,12 @@
 
 namespace NLog.UnitTests.LayoutRenderers
 {
+    using System.Collections.Generic;
     using System.Collections.Specialized;
+    using System.Configuration;
     using NLog.Internal;
     using NLog.LayoutRenderers;
-	using Xunit;
+    using Xunit;
 
     public class AppSettingTests : NLogTestBase
     {
@@ -109,14 +111,34 @@ public void NoAppSettingTest()
             Assert.Equal(string.Empty, rendered);
         }
 
-        private class MockConfigurationManager : IConfigurationManager
+        [Fact]
+        public void UseConnectionStringTest()
         {
-            public MockConfigurationManager()
+            var configurationManager = new MockConfigurationManager();
+            const string expected = "Hello Connection";
+            configurationManager.ConnectionStrings["myConnection"] = new ConnectionStringSettings() { ConnectionString = expected };
+            var appSettingLayoutRenderer = new AppSettingLayoutRenderer2
             {
-                AppSettings = new NameValueCollection();
-            }
+                ConfigurationManager = configurationManager,
+                Item = "ConnectionStrings.myConnection",
+            };
+
+            var rendered = appSettingLayoutRenderer.Render(LogEventInfo.CreateNullEvent());
 
-            public NameValueCollection AppSettings { get; private set; }
+            Assert.Equal(expected, rendered);
+        }
+
+        private class MockConfigurationManager : IConfigurationManager2
+        {
+            public NameValueCollection AppSettings { get; } = new NameValueCollection();
+
+            public Dictionary<string, ConnectionStringSettings> ConnectionStrings { get; } = new Dictionary<string, ConnectionStringSettings>();
+
+            public ConnectionStringSettings LookupConnectionString(string name)
+            {
+                ConnectionStrings.TryGetValue(name, out var value);
+                return value;
+            }
         }
     }
 }