Added conversion of properties to UpperCaseSnakeCase

Added conversion to UpperCaseSnakeCase in case the names of AppSettings class properties do not match the keys in the .env file.

Author: DevD4v3

src/Binder/EnvBinder.cs

@@ -1,3 +1,4 @@
+using System.Text;
 using System;
 using System.Collections.Generic;
 using System.Reflection;
@@ -42,19 +43,22 @@ public EnvBinder(IEnvironmentVariablesProvider provider)
         /// <inheritdoc />
         public TSettings Bind<TSettings>(out EnvValidationResult result) where TSettings : new()
         {
-            var settings = new TSettings();
-            var type = typeof(TSettings);
-            result = _validationResult;
+            var sb         = new StringBuilder(capacity: 40);
+            var envVars    = _configuration.EnvVars;
+            var settings   = new TSettings();
+            var type       = typeof(TSettings);
             var properties = _configuration.BindNonPublicProperties ? type.GetPublicAndNonPublicProperties() : type.GetProperties();
+            result         = _validationResult;
             foreach (PropertyInfo property in properties)
             {
                 if(IsReadOnlyOrWriteOnly(property)) 
                     continue;
 
                 var envKeyAttribute = (EnvKeyAttribute)Attribute.GetCustomAttribute(property, typeof(EnvKeyAttribute));
-                var variableName = envKeyAttribute is not null ? envKeyAttribute.Name : property.Name;
-                var retrievedValue = _configuration.EnvVars[variableName];
-
+                var variableName    = envKeyAttribute is not null ? envKeyAttribute.Name : property.Name;
+                var retrievedValue  = envVars[variableName];
+                retrievedValue    ??= envKeyAttribute is not null ? retrievedValue : envVars[variableName.ToUpperCaseSnakeCase(sb)];
+                sb.Clear();
                 if (retrievedValue is null)
                 {
                     string errorMsg;

src/Extensions/StringExtensions.cs

@@ -36,5 +36,21 @@ public static bool EndsWith(this string str, char value)
             int len = str.Length;
             return len != 0 && str[len - 1] == value;
         }
+
+        /// <summary>
+        /// Converts from PascalCase to UpperCaseSnakeCase.
+        /// </summary>
+        /// <param name="str"></param>
+        /// <param name="sb"></param>
+        /// <returns></returns>
+        public static string ToUpperCaseSnakeCase(this string str, StringBuilder sb)
+        {
+            int len = str.Length;
+            sb.Append(str[0]);
+            for (int i = 1; i < len; i++)
+                sb.Append(char.IsUpper(str[i]) ? $"_{str[i]}" : char.ToUpper(str[i]));
+
+            return sb.ToString();
+        }
     }
 }