Helper for parsing enums from string

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.9.7] - 2024-06-28
+
+- Add helper methods to parse enums from strings.
+
 ## [1.9.6] - 2024-06-12
 
 - Add `IEnumerable<T>` extension methods to remove LINQ dependency from generated code.

Microsoft.Kiota.Abstractions.Tests/EnumHelperTests.cs

@@ -0,0 +1,121 @@
+using Microsoft.Kiota.Abstractions.Helpers;
+using Microsoft.Kiota.Abstractions.Tests.Mocks;
+using Xunit;
+
+namespace Microsoft.Kiota.Abstractions.Tests
+{
+    public class EnumHelperTests
+    {
+        [Fact]
+        public void EnumGenericIsParsedIfValueIsInteger()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnum>("0");
+
+            Assert.Equal(TestEnum.First, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsGenericIsParsedIfValuesAreIntegers()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnumWithFlags>("1,2");
+
+            Assert.Equal(TestEnumWithFlags.Value1 | TestEnumWithFlags.Value2, result);
+        }
+
+        [Fact]
+        public void EnumGenericIsParsedIfValueIsString()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnum>("First");
+
+            Assert.Equal(TestEnum.First, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsGenericIsParsedIfValuesAreStrings()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnumWithFlags>("Value1,Value3");
+
+            Assert.Equal(TestEnumWithFlags.Value1 | TestEnumWithFlags.Value3, result);
+        }
+
+        [Fact]
+        public void EnumGenericIsParsedIfValueIsFromEnumMember()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnum>("Value_2");
+
+            Assert.Equal(TestEnum.Second, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsGenericIsParsedIfValuesAreFromEnumMember()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnumWithFlags>("Value__2,Value__3");
+
+            Assert.Equal(TestEnumWithFlags.Value2 | TestEnumWithFlags.Value3, result);
+        }
+
+        [Fact]
+        public void IfEnumGenericIsNotParsedThenNullIsReturned()
+        {
+            var result = EnumHelpers.GetEnumValue<TestEnum>("Value_5");
+
+            Assert.Null(result);
+        }
+
+        [Fact]
+        public void EnumIsParsedIfValueIsInteger()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnum), "0");
+
+            Assert.Equal(TestEnum.First, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsIsParsedIfValuesAreIntegers()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnumWithFlags), "1,2");
+
+            Assert.Equal(TestEnumWithFlags.Value1 | TestEnumWithFlags.Value2, result);
+        }
+
+        [Fact]
+        public void EnumIsParsedIfValueIsString()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnum), "First");
+
+            Assert.Equal(TestEnum.First, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsIsParsedIfValuesAreStrings()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnumWithFlags), "Value1,Value3");
+
+            Assert.Equal(TestEnumWithFlags.Value1 | TestEnumWithFlags.Value3, result);
+        }
+
+        [Fact]
+        public void EnumIsParsedIfValueIsFromEnumMember()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnum), "Value_2");
+
+            Assert.Equal(TestEnum.Second, result);
+        }
+
+        [Fact]
+        public void EnumWithFlagsIsParsedIfValuesAreFromEnumMember()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnumWithFlags), "Value__2,Value__3");
+
+            Assert.Equal(TestEnumWithFlags.Value2 | TestEnumWithFlags.Value3, result);
+        }
+
+        [Fact]
+        public void IfEnumIsNotParsedThenNullIsReturned()
+        {
+            var result = EnumHelpers.GetEnumValue(typeof(TestEnum), "Value_5");
+
+            Assert.Null(result);
+        }
+    }
+}

Microsoft.Kiota.Abstractions.Tests/Mocks/TestEnum.cs

@@ -1,11 +1,12 @@
+using System;
 using System.Runtime.Serialization;
 
 namespace Microsoft.Kiota.Abstractions.Tests.Mocks;
 
 public enum TestEnum
 {
-    [EnumMember(Value = "1")]
+    [EnumMember(Value = "Value_1")]
     First,
-    [EnumMember(Value = "2")]
+    [EnumMember(Value = "Value_2")]
     Second,
-}
+}

Microsoft.Kiota.Abstractions.Tests/Mocks/TestEnumWithFlags.cs

@@ -0,0 +1,15 @@
+using System;
+using System.Runtime.Serialization;
+
+namespace Microsoft.Kiota.Abstractions.Tests.Mocks;
+
+[Flags]
+public enum TestEnumWithFlags
+{
+    [EnumMember(Value = "Value__1")]
+    Value1 = 0x01,
+    [EnumMember(Value = "Value__2")]
+    Value2 = 0x02,
+    [EnumMember(Value = "Value__3")]
+    Value3 = 0x04
+}

Microsoft.Kiota.Abstractions.Tests/RequestInformationTests.cs

@@ -553,7 +553,7 @@ public void SetsEnumValueInQueryParameters()
             // Act
             testRequest.AddQueryParameters(new GetQueryParameters { DataSet = TestEnum.First });
             // Assert
-            Assert.Equal("http://localhost/me?dataset=1", testRequest.URI.ToString());
+            Assert.Equal("http://localhost/me?dataset=Value_1", testRequest.URI.ToString());
         }
         [Fact]
         public void SetsEnumValuesInQueryParameters()
@@ -567,7 +567,7 @@ public void SetsEnumValuesInQueryParameters()
             // Act
             testRequest.AddQueryParameters(new GetQueryParameters { DataSets = new TestEnum[] { TestEnum.First, TestEnum.Second } });
             // Assert
-            Assert.Equal("http://localhost/me?datasets=1,2", testRequest.URI.ToString());
+            Assert.Equal("http://localhost/me?datasets=Value_1,Value_2", testRequest.URI.ToString());
         }
         [Fact]
         public void SetsEnumValueInPathParameters()
@@ -581,7 +581,7 @@ public void SetsEnumValueInPathParameters()
             // Act
             testRequest.PathParameters.Add("dataset", TestEnum.First);
             // Assert
-            Assert.Equal("http://localhost/1", testRequest.URI.ToString());
+            Assert.Equal("http://localhost/Value_1", testRequest.URI.ToString());
         }
         [Fact]
         public void SetsEnumValuesInPathParameters()
@@ -595,7 +595,7 @@ public void SetsEnumValuesInPathParameters()
             // Act
             testRequest.PathParameters.Add("dataset", new TestEnum[] { TestEnum.First, TestEnum.Second });
             // Assert
-            Assert.Equal("http://localhost/1,2", testRequest.URI.ToString());
+            Assert.Equal("http://localhost/Value_1,Value_2", testRequest.URI.ToString());
         }
 
 

src/Helpers/EnumHelpers.cs

@@ -0,0 +1,171 @@
+using System;
+using System.Reflection;
+using System.Runtime.Serialization;
+
+#if NET5_0_OR_GREATER
+using System.Diagnostics.CodeAnalysis;
+#endif
+
+namespace Microsoft.Kiota.Abstractions.Helpers
+{
+    /// <summary>
+    /// Helper methods for enums
+    /// </summary>
+    public static class EnumHelpers
+    {
+        /// <summary>
+        /// Gets the enum value from the raw value
+        /// </summary>
+        /// <typeparam name="T">Enum type</typeparam>
+        /// <param name="rawValue">Raw value</param>
+        /// <returns></returns>
+#if NET5_0_OR_GREATER
+        public static T? GetEnumValue<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] T>(string rawValue) where T : struct, Enum
+#else
+        public static T? GetEnumValue<T>(string rawValue) where T : struct, Enum
+#endif
+        {
+            if(string.IsNullOrEmpty(rawValue)) return null;
+
+            var type = typeof(T);
+            rawValue = ToEnumRawName<T>(rawValue!);
+            if(typeof(T).IsDefined(typeof(FlagsAttribute)))
+            {
+                ReadOnlySpan<char> valueSpan = rawValue.AsSpan();
+                int value = 0;
+                while(valueSpan.Length > 0)
+                {
+                    int commaIndex = valueSpan.IndexOf(',');
+                    ReadOnlySpan<char> valueNameSpan = commaIndex < 0 ? valueSpan : valueSpan.Slice(0, commaIndex);
+                    valueNameSpan = ToEnumRawName<T>(valueNameSpan);
+#if NET6_0_OR_GREATER
+                    if(Enum.TryParse<T>(valueNameSpan, true, out var result))
+#else
+                    if(Enum.TryParse<T>(valueNameSpan.ToString(), true, out var result))
+#endif
+                        value |= (int)(object)result;
+                    valueSpan = commaIndex < 0 ? ReadOnlySpan<char>.Empty : valueSpan.Slice(commaIndex + 1);
+                }
+                return (T)(object)value;
+            }
+            else
+                return Enum.TryParse<T>(rawValue, true, out var result) ? result : null;
+        }
+
+#if NET5_0_OR_GREATER
+        private static string ToEnumRawName<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] T>(string value) where T : struct, Enum
+#else
+        private static string ToEnumRawName<T>(string value) where T : struct, Enum
+#endif
+        {
+            if(TryGetFieldValueName(typeof(T), value, out var val))
+            {
+                value = val;
+            }
+
+            return value;
+        }
+
+#if NET5_0_OR_GREATER
+        private static ReadOnlySpan<char> ToEnumRawName<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] T>(ReadOnlySpan<char> span) where T : struct, Enum
+#else
+        private static ReadOnlySpan<char> ToEnumRawName<T>(ReadOnlySpan<char> span) where T : struct, Enum
+#endif
+        {
+            var value = span.ToString();
+            if(TryGetFieldValueName(typeof(T), value, out var val))
+            {
+                value = val;
+            }
+
+            return value.AsSpan();
+        }
+
+        /// <summary>
+        /// Gets the enum value from the raw value for the given type
+        /// </summary>
+        /// <param name="type">Enum type</param>
+        /// <param name="rawValue">Raw value</param>
+        /// <returns></returns>
+#if NET5_0_OR_GREATER
+        public static object? GetEnumValue([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] Type? type, string rawValue)
+#else
+        public static object? GetEnumValue(Type? type, string rawValue)
+#endif
+        {
+            object? result;
+            if(type == null)
+            {
+                return null;
+            }
+            if(type.IsDefined(typeof(FlagsAttribute)))
+            {
+                int intValue = 0;
+                while(rawValue.Length > 0)
+                {
+                    int commaIndex = rawValue.IndexOf(',');
+                    var valueName = commaIndex < 0 ? rawValue : rawValue.Substring(0, commaIndex);
+                    if(TryGetFieldValueName(type, valueName, out var value))
+                    {
+                        valueName = value;
+                    }
+#if NET5_0_OR_GREATER
+                    if(Enum.TryParse(type, valueName, true, out var enumPartResult))
+                        intValue |= (int)enumPartResult!;
+#else
+                    try
+                    {
+                        intValue |= (int)Enum.Parse(type, valueName, true);
+                    }
+                    catch { }
+#endif
+
+                    rawValue = commaIndex < 0 ? string.Empty : rawValue.Substring(commaIndex + 1);
+                }
+                result = intValue > 0 ? Enum.Parse(type, intValue.ToString(), true) : null;
+            }
+            else
+            {
+                if(TryGetFieldValueName(type, rawValue, out var value))
+                {
+                    rawValue = value;
+                }
+
+#if NET5_0_OR_GREATER
+                Enum.TryParse(type, rawValue, true, out object? enumResult);
+                result = enumResult;
+#else
+                try
+                {
+                    result = Enum.Parse(type, rawValue, true);
+                }
+                catch
+                {
+                    result = null;
+                }
+#endif
+            }
+            return result;
+
+
+        }
+
+#if NET5_0_OR_GREATER
+        private static bool TryGetFieldValueName([DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicFields)] Type type, string rawValue, out string valueName)
+#else
+        private static bool TryGetFieldValueName(Type type, string rawValue, out string valueName)
+#endif
+        {
+            valueName = string.Empty;
+            foreach(var field in type.GetFields())
+            {
+                if(field.GetCustomAttribute<EnumMemberAttribute>() is { } attr && rawValue.Equals(attr.Value, StringComparison.Ordinal))
+                {
+                    valueName = field.Name;
+                    return true;
+                }
+            }
+            return false;
+        }
+    }
+}

src/Microsoft.Kiota.Abstractions.csproj

@@ -15,7 +15,7 @@
     <PackageProjectUrl>https://aka.ms/kiota/docs</PackageProjectUrl>
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
     <Deterministic>true</Deterministic>
-    <VersionPrefix>1.9.6</VersionPrefix>
+    <VersionPrefix>1.9.7</VersionPrefix>
     <VersionSuffix></VersionSuffix>
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
     <SignAssembly>false</SignAssembly>