Use deferred construction if there are required members (fix #71)

src/Dapper.AOT.Analyzers/CodeAnalysis/DapperInterceptorGenerator.cs

@@ -690,13 +690,14 @@ private static void WriteRowFactory(in GenerateState context, CodeWriter sb, ITy
         }
 
         var hasInitOnlyMembers = members.Any(member => member.IsInitOnly);
+        var hasRequiredMembers = members.Any(member => member.IsRequired);
         var hasGetOnlyMembers = members.Any(member => member is { IsGettable: true, IsSettable: false, IsInitOnly: false });
         var useConstructorDeferred = map.Constructor is not null;
         var useFactoryMethodDeferred = map.FactoryMethod is not null;
 
         // Implementation detail: 
         // constructor takes advantage over factory method.
-        var useDeferredConstruction = useConstructorDeferred || useFactoryMethodDeferred || hasInitOnlyMembers || hasGetOnlyMembers;
+        var useDeferredConstruction = useConstructorDeferred || useFactoryMethodDeferred || hasInitOnlyMembers || hasGetOnlyMembers || hasRequiredMembers;
 
         WriteRowFactoryHeader();
 

src/Dapper.AOT.Analyzers/Internal/CodeWriter.cs

@@ -201,6 +201,14 @@ public static bool IsSettableInstanceMember(ISymbol symbol, out ITypeSymbol type
         return false;
     }
 
+    public static bool IsRequired(ISymbol symbol)
+        => symbol switch
+        {
+            IPropertySymbol prop => prop.IsRequired,
+            IFieldSymbol field => field.IsRequired,
+            _ => false,
+        };
+
     public static bool IsInitOnlyInstanceMember(ISymbol symbol, out ITypeSymbol type)
     {
         if (symbol.DeclaredAccessibility == Accessibility.Public && !symbol.IsStatic)

src/Dapper.AOT.Analyzers/Internal/Inspection.cs

@@ -412,6 +412,7 @@ public readonly struct ElementMember
         public bool IsGettable => (_flags & ElementMemberFlags.IsGettable) != 0;
         public bool IsSettable => (_flags & ElementMemberFlags.IsSettable) != 0;
         public bool IsInitOnly => (_flags & ElementMemberFlags.IsInitOnly) != 0;
+        public bool IsRequired => (_flags & ElementMemberFlags.IsRequired) != 0;
         public bool IsExpandable => (_flags & ElementMemberFlags.IsExpandable) != 0;
 
         /// <summary>
@@ -438,6 +439,7 @@ public enum ElementMemberFlags
             IsSettable = 1 << 1,
             IsInitOnly = 1 << 2,
             IsExpandable = 1 << 3,
+            IsRequired = 1 << 4,
         }
 
         public ElementMember(
@@ -711,6 +713,7 @@ internal static ImmutableArray<ElementMember> GetMembers(bool forParameters, ITy
                 if (CodeWriter.IsGettableInstanceMember(member, out _)) flags |= ElementMember.ElementMemberFlags.IsGettable;
                 if (CodeWriter.IsSettableInstanceMember(member, out _)) flags |= ElementMember.ElementMemberFlags.IsSettable;
                 if (CodeWriter.IsInitOnlyInstanceMember(member, out _)) flags |= ElementMember.ElementMemberFlags.IsInitOnly;
+                if (CodeWriter.IsRequired(member)) flags |= ElementMember.ElementMemberFlags.IsRequired;
 
                 if (forParameters)
                 {

test/Dapper.AOT.Test/Interceptors/RequiredProperties.input.cs

@@ -0,0 +1,37 @@
+using Dapper;
+using Microsoft.Data.SqlClient;
+using System.Threading.Tasks;
+
+[DapperAot]
+
+public class SomeType
+{
+    public int Id { get; set; }
+    public required string Title { get; set; }
+    public bool IsComplete { get; set; }
+
+    public Task<SomeType> Insert(SqlConnection connection)
+        => connection.QuerySingleAsync<SomeType>("""
+            INSERT INTO MyTable(Title, IsComplete)
+            Values(@Title, @IsComplete)
+            RETURNING *
+        """, this);
+}
+
+
+namespace System.Runtime.CompilerServices
+{
+    [System.AttributeUsage(System.AttributeTargets.All, AllowMultiple = true, Inherited = false)]
+    sealed file class CompilerFeatureRequiredAttribute : Attribute
+    {
+        public CompilerFeatureRequiredAttribute(string _) { }
+    }
+
+    [System.AttributeUsage(System.AttributeTargets.Class | System.AttributeTargets.Field | System.AttributeTargets.Property | System.AttributeTargets.Struct, AllowMultiple = false, Inherited = false)]
+    sealed file class RequiredMemberAttribute : Attribute {}
+}
+namespace System.Diagnostics.CodeAnalysis
+{
+    [System.AttributeUsage(System.AttributeTargets.Constructor, AllowMultiple = false, Inherited = false)]
+    sealed file class SetsRequiredMembersAttribute : Attribute { }
+}

test/Dapper.AOT.Test/Interceptors/RequiredProperties.output.cs

@@ -0,0 +1,164 @@
+#nullable enable
+namespace Dapper.AOT // interceptors must be in a known namespace
+{
+    file static class DapperGeneratedInterceptors
+    {
+        [global::System.Runtime.CompilerServices.InterceptsLocationAttribute("Interceptors\\RequiredProperties.input.cs", 14, 23)]
+        internal static global::System.Threading.Tasks.Task<global::SomeType> QuerySingleAsync0(this global::System.Data.IDbConnection cnn, string sql, object? param, global::System.Data.IDbTransaction? transaction, int? commandTimeout, global::System.Data.CommandType? commandType)
+        {
+            // Query, Async, TypedResult, HasParameters, SingleRow, Text, AtLeastOne, AtMostOne, BindResultsByName, KnownParameters
+            // takes parameter: global::SomeType
+            // parameter map: IsComplete Title
+            // returns data: global::SomeType
+            global::System.Diagnostics.Debug.Assert(!string.IsNullOrWhiteSpace(sql));
+            global::System.Diagnostics.Debug.Assert((commandType ?? global::Dapper.DapperAotExtensions.GetCommandType(sql)) == global::System.Data.CommandType.Text);
+            global::System.Diagnostics.Debug.Assert(param is not null);
+
+            return global::Dapper.DapperAotExtensions.Command(cnn, transaction, sql, global::System.Data.CommandType.Text, commandTimeout.GetValueOrDefault(), CommandFactory0.Instance).QuerySingleAsync((global::SomeType)param!, RowFactory0.Instance);
+
+        }
+
+        private class CommonCommandFactory<T> : global::Dapper.CommandFactory<T>
+        {
+            public override global::System.Data.Common.DbCommand GetCommand(global::System.Data.Common.DbConnection connection, string sql, global::System.Data.CommandType commandType, T args)
+            {
+                var cmd = base.GetCommand(connection, sql, commandType, args);
+                // apply special per-provider command initialization logic for OracleCommand
+                if (cmd is global::Oracle.ManagedDataAccess.Client.OracleCommand cmd0)
+                {
+                    cmd0.BindByName = true;
+                    cmd0.InitialLONGFetchSize = -1;
+
+                }
+                return cmd;
+            }
+
+        }
+
+        private static readonly CommonCommandFactory<object?> DefaultCommandFactory = new();
+
+        private sealed class RowFactory0 : global::Dapper.RowFactory<global::SomeType>
+        {
+            internal static readonly RowFactory0 Instance = new();
+            private RowFactory0() {}
+            public override object? Tokenize(global::System.Data.Common.DbDataReader reader, global::System.Span<int> tokens, int columnOffset)
+            {
+                for (int i = 0; i < tokens.Length; i++)
+                {
+                    int token = -1;
+                    var name = reader.GetName(columnOffset);
+                    var type = reader.GetFieldType(columnOffset);
+                    switch (NormalizedHash(name))
+                    {
+                        case 926444256U when NormalizedEquals(name, "id"):
+                            token = type == typeof(int) ? 0 : 3; // two tokens for right-typed and type-flexible
+                            break;
+                        case 2556802313U when NormalizedEquals(name, "title"):
+                            token = type == typeof(string) ? 1 : 4;
+                            break;
+                        case 2563538258U when NormalizedEquals(name, "iscomplete"):
+                            token = type == typeof(bool) ? 2 : 5;
+                            break;
+
+                    }
+                    tokens[i] = token;
+                    columnOffset++;
+
+                }
+                return null;
+            }
+            public override global::SomeType Read(global::System.Data.Common.DbDataReader reader, global::System.ReadOnlySpan<int> tokens, int columnOffset, object? state)
+            {
+                int value0 = default;
+                string? value1 = default;
+                bool value2 = default;
+                foreach (var token in tokens)
+                {
+                    switch (token)
+                    {
+                        case 0:
+                            value0 = reader.GetInt32(columnOffset);
+                            break;
+                        case 3:
+                            value0 = GetValue<int>(reader, columnOffset);
+                            break;
+                        case 1:
+                            value1 = reader.IsDBNull(columnOffset) ? (string?)null : reader.GetString(columnOffset);
+                            break;
+                        case 4:
+                            value1 = reader.IsDBNull(columnOffset) ? (string?)null : GetValue<string>(reader, columnOffset);
+                            break;
+                        case 2:
+                            value2 = reader.GetBoolean(columnOffset);
+                            break;
+                        case 5:
+                            value2 = GetValue<bool>(reader, columnOffset);
+                            break;
+
+                    }
+                    columnOffset++;
+
+                }
+                return new global::SomeType
+                {
+                    Id = value0,
+                    Title = value1,
+                    IsComplete = value2,
+                };
+            }
+        }
+
+        private sealed class CommandFactory0 : CommonCommandFactory<global::SomeType>
+        {
+            internal static readonly CommandFactory0 Instance = new();
+            public override void AddParameters(in global::Dapper.UnifiedCommand cmd, global::SomeType args)
+            {
+                var ps = cmd.Parameters;
+                global::System.Data.Common.DbParameter p;
+                p = cmd.CreateParameter();
+                p.ParameterName = "Title";
+                p.DbType = global::System.Data.DbType.String;
+                p.Size = -1;
+                p.Direction = global::System.Data.ParameterDirection.Input;
+                p.Value = AsValue(args.Title);
+                ps.Add(p);
+
+                p = cmd.CreateParameter();
+                p.ParameterName = "IsComplete";
+                p.DbType = global::System.Data.DbType.Boolean;
+                p.Direction = global::System.Data.ParameterDirection.Input;
+                p.Value = AsValue(args.IsComplete);
+                ps.Add(p);
+
+            }
+            public override void UpdateParameters(in global::Dapper.UnifiedCommand cmd, global::SomeType args)
+            {
+                var ps = cmd.Parameters;
+                ps[0].Value = AsValue(args.Title);
+                ps[1].Value = AsValue(args.IsComplete);
+
+            }
+            public override bool CanPrepare => true;
+
+        }
+
+
+    }
+}
+namespace System.Runtime.CompilerServices
+{
+    // this type is needed by the compiler to implement interceptors - it doesn't need to
+    // come from the runtime itself, though
+
+    [global::System.Diagnostics.Conditional("DEBUG")] // not needed post-build, so: evaporate
+    [global::System.AttributeUsage(global::System.AttributeTargets.Method, AllowMultiple = true)]
+    sealed file class InterceptsLocationAttribute : global::System.Attribute
+    {
+        public InterceptsLocationAttribute(string path, int lineNumber, int columnNumber)
+        {
+            _ = path;
+            _ = lineNumber;
+            _ = columnNumber;
+        }
+    }
+}