feat(lib): Improve handling of types with generic arguments #123

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [unreleased]
 
+### Added
+
+- Better support for generic types (#123)
+
 ## [0.16.0] - 2024-12-17
 
 ### Added

TypeContractor.Tests/TypeScript/TypeScriptConverterTests.cs

@@ -343,6 +343,26 @@ public void Handles_Nullable_Records_Inside_Other_Records()
 		second.IsNullable.Should().BeTrue();
 	}
 
+	[Fact]
+	public void Handles_Generics()
+	{
+		var result = Sut.Convert(typeof(ResponseWithOverrides));
+
+		result.Should().NotBeNull();
+		result.Properties.Should().NotBeNull();
+		result.Properties!.Should().HaveCount(2);
+		result.Properties!.First().DestinationType.Should().Be("Overridable<string>");
+		result.Properties!.Last().DestinationType.Should().Be("Overridable<boolean?>");
+
+		Sut.CustomMappedTypes.Should().ContainSingle();
+		var overridableType = Sut.CustomMappedTypes.First().Value;
+		overridableType.Properties.Should().HaveCount(2);
+		overridableType.Properties!.First().DestinationName.Should().Be("value");
+		overridableType.Properties!.First().DestinationType.Should().Be("T");
+		overridableType.Properties!.Last().DestinationName.Should().Be("isOverridden");
+		overridableType.Properties!.Last().DestinationType.Should().Be("boolean");
+	}
+
 #pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 	private record TopLevelRecord(string Name, SecondStoryRecord? SecondStoryRecord);
 	private record SecondStoryRecord(string Description, SomeOtherDeeplyNestedRecord? SomeOtherDeeplyNestedRecord);
@@ -466,6 +486,18 @@ private class TimeOnlyResponse
 		public TimeOnly MeetingTime { get; set; }
 	}
 
+	private class Overridable<T>
+	{
+		public T? Value { get; set; }
+		public bool IsOverridden { get; set; }
+	}
+
+	private class ResponseWithOverrides
+	{
+		public Overridable<string> Name { get; set; }
+		public Overridable<bool?> SomeBool { get; set; }
+	}
+
 #pragma warning restore CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
 	private MetadataLoadContext BuildMetadataLoadContext()

TypeContractor/Output/DestinationType.cs

@@ -1,13 +1,36 @@
 namespace TypeContractor.Output;
 
-public record DestinationType(string TypeName, string? FullName, string ImportType, bool IsBuiltin, bool IsArray, bool IsReadonly, bool IsNullable, Type? InnerType)
+public record DestinationType(
+	string TypeName,
+	string? FullName,
+	string ImportType,
+	bool IsBuiltin,
+	bool IsArray,
+	bool IsReadonly,
+	bool IsNullable,
+	bool IsGeneric,
+	ICollection<DestinationType> GenericTypeArguments,
+	Type? SourceType,
+	Type? InnerType)
 {
-	public DestinationType(string typeName, string? fullName, bool isBuiltin, bool isArray, bool isReadonly, bool isNullable, Type? innerType, string? importType = null) : this(typeName, fullName, importType ?? typeName, isBuiltin, isArray, isReadonly, isNullable, innerType)
+	public DestinationType(string typeName,
+						string? fullName,
+						bool isBuiltin,
+						bool isArray,
+						bool isReadonly,
+						bool isNullable,
+						bool isGeneric,
+						ICollection<DestinationType> genericTypeArguments,
+						Type? innerType,
+						Type? sourceType,
+						string? importType = null) : this(typeName, fullName, importType ?? typeName, isBuiltin, isArray, isReadonly, isNullable, isGeneric, genericTypeArguments, sourceType, innerType)
 	{
 	}
 
 	/// <summary>
 	/// Returns the <see cref="TypeName"/> and array brackets if the type is an array
 	/// </summary>
 	public string FullTypeName => $"{TypeName}{(IsArray ? "[]" : "")}";
+
+	public string DestinationTypeName => $"{TypeName}{(IsNullable ? "?" : "")}";
 }

TypeContractor/Output/OutputProperty.cs

@@ -1,6 +1,18 @@
 namespace TypeContractor.Output;
 
-public class OutputProperty(string sourceName, Type sourceType, Type? innerSourceType, string destinationName, string destinationType, string importType, bool isBuiltin, bool isArray, bool isNullable, bool isReadonly)
+public class OutputProperty(
+	string sourceName,
+	Type sourceType,
+	Type? innerSourceType,
+	string destinationName,
+	string destinationType,
+	string importType,
+	bool isBuiltin,
+	bool isArray,
+	bool isNullable,
+	bool isReadonly,
+	bool isGeneric,
+	ICollection<DestinationType> genericTypeArguments)
 {
 	public string SourceName { get; set; } = sourceName;
 	public Type SourceType { get; set; } = sourceType;
@@ -12,6 +24,8 @@ public class OutputProperty(string sourceName, Type sourceType, Type? innerSourc
 	public bool IsArray { get; set; } = isArray;
 	public bool IsNullable { get; set; } = isNullable;
 	public bool IsReadonly { get; set; } = isReadonly;
+	public bool IsGeneric { get; set; } = isGeneric;
+	public ICollection<DestinationType> GenericTypeArguments { get; } = genericTypeArguments;
 	public ObsoleteInfo? Obsolete { get; set; }
 
 	/// <summary>
@@ -37,6 +51,8 @@ public override bool Equals(object? obj)
 			   IsArray == property.IsArray &&
 			   IsNullable == property.IsNullable &&
 			   IsReadonly == property.IsReadonly &&
+			   IsGeneric == property.IsGeneric &&
+			   GenericTypeArguments.SequenceEqual(property.GenericTypeArguments) &&
 			   EqualityComparer<ObsoleteInfo?>.Default.Equals(Obsolete, property.Obsolete);
 	}
 
@@ -53,6 +69,7 @@ public override int GetHashCode()
 		hash.Add(IsArray);
 		hash.Add(IsNullable);
 		hash.Add(IsReadonly);
+		hash.Add(IsGeneric);
 		hash.Add(Obsolete);
 		return hash.ToHashCode();
 	}

TypeContractor/Output/OutputType.cs

@@ -1,9 +1,18 @@
-using System.Globalization;
+using System.Globalization;
 using System.Text;
 
 namespace TypeContractor.Output;
 
-public record OutputType(string Name, string FullName, string FileName, ContractedType ContractedType, bool IsEnum, ICollection<OutputProperty>? Properties, ICollection<OutputEnumMember>? EnumMembers)
+public record OutputType(
+	string Name,
+	string FullName,
+	string FileName,
+	ContractedType ContractedType,
+	bool IsEnum,
+	bool IsGeneric,
+	ICollection<DestinationType> GenericTypeArguments,
+	ICollection<OutputProperty>? Properties,
+	ICollection<OutputEnumMember>? EnumMembers)
 {
 	public override string ToString()
 	{

TypeContractor/TypeScript/TypeScriptConverter.cs

@@ -18,12 +18,16 @@ public OutputType Convert(Type type, ContractedType? contractedType = null)
 	{
 		ArgumentNullException.ThrowIfNull(type);
 
+		var typeName = type.Name.Split('`').First();
+
 		return new(
-			type.Name,
+			typeName,
 			type.FullName!,
-			CasingHelpers.ToCasing(type.Name.Replace("_", ""), configuration.Casing),
-			contractedType ?? ContractedType.FromName(type.FullName!, type, configuration),
+			CasingHelpers.ToCasing(typeName.Replace("_", ""), configuration.Casing),
+			contractedType ?? ContractedType.FromName(type.FullName ?? typeName, type, configuration),
 			type.IsEnum,
+			type.IsGenericType,
+			type.IsGenericType ? ((TypeInfo)type).GenericTypeParameters.Select(x => GetDestinationType(x, [], false, TypeChecks.IsNullable(x))).ToList() : [],
 			type.IsEnum ? null : GetProperties(type).Distinct().ToList(),
 			type.IsEnum ? GetEnumProperties(type) : null
 		);
@@ -71,7 +75,19 @@ private List<OutputProperty> GetProperties(Type type)
 
 			var destinationName = GetDestinationName(property.Name);
 			var destinationType = GetDestinationType(property.PropertyType, property.CustomAttributes, isReadonly, TypeChecks.IsNullable(property.PropertyType));
-			var outputProperty = new OutputProperty(property.Name, property.PropertyType, destinationType.InnerType, destinationName, destinationType.TypeName, destinationType.ImportType, destinationType.IsBuiltin, destinationType.IsArray, TypeChecks.IsNullable(property), destinationType.IsReadonly);
+			var outputProperty = new OutputProperty(
+				property.Name,
+				property.PropertyType,
+				destinationType.InnerType,
+				destinationName,
+				destinationType.TypeName,
+				destinationType.ImportType,
+				destinationType.IsBuiltin,
+				destinationType.IsArray,
+				TypeChecks.IsNullable(property),
+				destinationType.IsReadonly,
+				destinationType.IsGeneric,
+				destinationType.GenericTypeArguments);
 
 			var obsolete = property.CustomAttributes.FirstOrDefault(x => x.AttributeType.FullName == "System.ObsoleteAttribute");
 			outputProperty.Obsolete = obsolete is not null ? new ObsoleteInfo((string?)obsolete.ConstructorArguments.FirstOrDefault().Value) : null;
@@ -94,11 +110,14 @@ private List<OutputProperty> GetProperties(Type type)
 
 	public DestinationType GetDestinationType(in Type sourceType, IEnumerable<CustomAttributeData> customAttributes, bool isReadonly, bool isNullable)
 	{
-		if (configuration.TypeMaps.TryGetValue(sourceType.FullName!, out var destType))
-			return new DestinationType(destType.Replace("[]", string.Empty), sourceType.FullName, true, destType.Contains("[]"), isReadonly, isNullable || TypeChecks.IsNullable(sourceType), null);
+		if (!sourceType.IsGenericParameter && configuration.TypeMaps.TryGetValue(sourceType.FullName!, out var destType))
+			return new DestinationType(destType.Replace("[]", string.Empty), sourceType.FullName, true, destType.Contains("[]"), isReadonly, isNullable || TypeChecks.IsNullable(sourceType), false, [], null, sourceType);
 
 		if (CustomMappedTypes.TryGetValue(sourceType, out var customType))
-			return new DestinationType(customType.Name, customType.FullName, false, false, isReadonly, TypeChecks.IsNullable(sourceType), null);
+			return new DestinationType(customType.Name, customType.FullName, false, false, isReadonly, TypeChecks.IsNullable(sourceType), customType.IsGeneric, customType.GenericTypeArguments, null, customType.ContractedType.Type);
+
+		if (sourceType.IsGenericTypeParameter)
+			return new DestinationType(sourceType.Name, null, true, false, false, isNullable, true, [], null, sourceType, "");
 
 		if (TypeChecks.ImplementsIDictionary(sourceType))
 		{
@@ -108,15 +127,15 @@ public DestinationType GetDestinationType(in Type sourceType, IEnumerable<Custom
 
 			var isBuiltin = keyType.IsBuiltin && valueDestinationType.IsBuiltin;
 
-			return new DestinationType($"{{ [key: {keyType.TypeName}]: {valueDestinationType.FullTypeName} }}", valueDestinationType.FullName, isBuiltin, false, isReadonly, valueDestinationType.IsNullable, valueType, valueDestinationType.ImportType);
+			return new DestinationType($"{{ [key: {keyType.TypeName}]: {valueDestinationType.FullTypeName} }}", valueDestinationType.FullName, isBuiltin, false, isReadonly, valueDestinationType.IsNullable, valueDestinationType.IsGeneric, valueDestinationType.GenericTypeArguments, valueType, valueDestinationType.SourceType, valueDestinationType.ImportType);
 		}
 
 		if (TypeChecks.ImplementsIEnumerable(sourceType))
 		{
 			var innerType = TypeChecks.GetGenericType(sourceType);
 
-			var (TypeName, FullName, _, IsBuiltin, _, IsReadonly, IsNullable, _) = GetDestinationType(innerType, customAttributes, isReadonly, isNullable);
-			return new DestinationType(TypeName, FullName, IsBuiltin, true, IsReadonly, IsNullable, innerType);
+			var (TypeName, FullName, _, IsBuiltin, _, IsReadonly, IsNullable, IsGeneric, _, _, _) = GetDestinationType(innerType, customAttributes, isReadonly, isNullable);
+			return new DestinationType(TypeName, FullName, IsBuiltin, true, IsReadonly, IsNullable, IsGeneric, [], innerType, sourceType);
 		}
 
 		if (TypeChecks.IsValueTuple(sourceType))
@@ -128,21 +147,37 @@ public DestinationType GetDestinationType(in Type sourceType, IEnumerable<Custom
 			var argumentList = argumentDestinationTypes.Select((arg, idx) => $"item{idx + 1}: {arg.FullTypeName}");
 			var typeName = $"{{ {string.Join(", ", argumentList)} }}";
 
-			return new DestinationType(typeName, sourceType.FullName, isBuiltin, false, isReadonly, false, null);
+			return new DestinationType(typeName, sourceType.FullName, isBuiltin, false, isReadonly, false, false, [], null, sourceType);
 		}
 
 		if (TypeChecks.IsNullable(sourceType))
 		{
 			return GetDestinationType(sourceType.GenericTypeArguments.First(), customAttributes, isReadonly, true);
 		}
 
+		if (sourceType.IsGenericType && sourceType.GenericTypeArguments.Length > 0)
+		{
+			var genericType = sourceType.GetGenericTypeDefinition();
+			var genericOutputType = Convert(genericType);
+			CustomMappedTypes.TryAdd(genericType, genericOutputType);
+
+			var genericArguments = sourceType.GenericTypeArguments
+				.Select(x => GetDestinationType(x, customAttributes, isReadonly, TypeChecks.IsNullable(x)))
+				.ToList();
+
+			var importType = genericOutputType.Name.Split('`').First();
+			var typeName = importType + $"<{string.Join(", ", genericArguments.Select(x => x.DestinationTypeName))}>";
+
+			return new DestinationType(typeName, genericOutputType.FullName, false, false, isReadonly, isNullable, true, genericArguments, null, genericOutputType.ContractedType.Type, importType);
+		}
+
 		if (customAttributes.Any(x => x.AttributeType.FullName == "System.Runtime.CompilerServices.DynamicAttribute"))
-			return new DestinationType(DestinationTypes.Dynamic, null, true, false, isReadonly, true, null);
+			return new DestinationType(DestinationTypes.Dynamic, null, true, false, isReadonly, true, false, [], null, null);
 
 		// FIXME: Check if this is one of our types?
 		var outputType = Convert(sourceType);
 		CustomMappedTypes.Add(sourceType, outputType);
-		return new DestinationType(outputType.Name, outputType.FullName, false, false, isReadonly, isNullable || TypeChecks.IsNullable(sourceType), null);
+		return new DestinationType(outputType.Name, outputType.FullName, false, false, isReadonly, isNullable || TypeChecks.IsNullable(sourceType), outputType.IsGeneric, outputType.GenericTypeArguments, null, sourceType);
 
 		// throw new ArgumentException($"Unexpected type: {sourceType}");
 	}

TypeContractor/TypeScript/TypeScriptWriter.cs

@@ -48,12 +48,25 @@ private void BuildHeader()
 
 	private void BuildImports(OutputType type, IEnumerable<OutputType> allTypes, bool buildZodSchema)
 	{
-		var properties = type.Properties ?? Enumerable.Empty<OutputProperty>();
+		var properties = type.Properties ?? [];
 		var imports = properties
 			.Where(p => !p.IsBuiltin)
 			.DistinctBy(p => p.InnerSourceType ?? p.SourceType)
 			.ToList();
 
+		foreach (var property in properties)
+		{
+			if (!property.IsGeneric) continue;
+			if (property.GenericTypeArguments.Count == 0) continue;
+
+			foreach (var genArg in property.GenericTypeArguments)
+			{
+				if (genArg.IsBuiltin) continue;
+				if (genArg.InnerType is null && genArg.SourceType is null) continue;
+				imports.Add(new OutputProperty(genArg.TypeName, (genArg.InnerType ?? genArg.SourceType)!, null, "", genArg.DestinationTypeName, genArg.ImportType, false, genArg.IsArray, genArg.IsNullable, genArg.IsReadonly, genArg.IsGeneric, genArg.GenericTypeArguments));
+			}
+		}
+
 		if (buildZodSchema)
 			_builder.AppendLine(ZodSchemaWriter.LibraryImport);
 
@@ -117,7 +130,14 @@ private void BuildExport(OutputType type)
 		}
 		else
 		{
-			_builder.AppendLine($"export interface {type.Name} {{");
+			var genericPropertyTypes = type.IsGeneric
+				? type.GenericTypeArguments ?? []
+				: [];
+			var genericTypeArguments = genericPropertyTypes.Count > 0
+				? $"<{string.Join(", ", genericPropertyTypes.Select(x => x.TypeName))}>"
+				: "";
+
+			_builder.AppendLine($"export interface {type.Name}{genericTypeArguments} {{");
 		}
 
 		// Body
@@ -168,6 +188,11 @@ private static List<OutputType> GetImportedTypes(IEnumerable<OutputType> allType
 			return allTypes.Where(x => x.FullName == keyType.FullName || x.FullName == valueType.FullName).ToList();
 		}
 
+		if (import.IsGeneric && import.GenericTypeArguments.Count > 0)
+			return allTypes
+				.Where(x => x.FullName == $"{sourceType.Namespace}.{sourceType.Name}")
+				.ToList();
+
 		return allTypes.Where(x => x.FullName == sourceType.FullName).ToList();
 	}
 }

TypeContractor/TypeScript/ZodSchemaWriter.cs

@@ -35,7 +35,9 @@ public static void Write(OutputType type, IEnumerable<OutputType> allTypes, Stri
 
 		public static string? BuildImport(OutputProperty import)
 		{
-			var sourceType = import.SourceType.IsGenericType ? TypeChecks.GetGenericType(import.SourceType) : import.InnerSourceType ?? import.SourceType;
+			var sourceType = import.SourceType.IsGenericType && (import.GenericTypeArguments.Count == 0 || !import.GenericTypeArguments.All(x => x.IsBuiltin))
+				? TypeChecks.GetGenericType(import.SourceType)
+				: import.InnerSourceType ?? import.SourceType;
 
 			// We don't currently import any schema for enums
 			if (sourceType.IsEnum)
@@ -60,6 +62,7 @@ private static string GetImportType(Type? innerSourceType, Type sourceType)
 				return GetImportType(TypeChecks.GetGenericType(innerSourceType), sourceType);
 
 			var name = innerSourceType?.Name ?? sourceType.Name;
+			name = name.Split('`').First();
 			return name;
 		}
 
@@ -85,6 +88,7 @@ private static string GetImportType(Type? innerSourceType, Type sourceType)
 			else if (!property.IsBuiltin && !property.IsNullable)
 			{
 				var name = property.InnerSourceType?.Name ?? property.SourceType.Name;
+				name = name.Split('`').First();
 				output = $"{name}Schema";
 			}
 			else if (property.IsBuiltin)
@@ -94,11 +98,12 @@ private static string GetImportType(Type? innerSourceType, Type sourceType)
 			else if (!property.IsBuiltin && property.IsArray && property.InnerSourceType is not null)
 			{
 				var name = property.InnerSourceType.Name;
+				name = name.Split('`').First();
 				output = $"{name}Schema";
 			}
 			else
 			{
-				output = $"{property.SourceType.Name}Schema";
+				output = $"{property.SourceType.Name.Split('`').First()}Schema";
 			}
 
 			if (property.IsArray)