fix column.length load (#350)

(cherry picked from commit 4d990e8)

Author: MaceWindu

Source/LinqToDB.EntityFrameworkCore/EFCoreMetadataReader.cs

@@ -308,22 +308,25 @@ public MappingAttribute[] GetAttributes(Type type, MemberInfo memberInfo)
 					var skipOnUpdate = behaviour != PropertySaveBehavior.Save ||
 						prop.ValueGenerated.HasFlag(ValueGenerated.OnUpdate);
 
-					(result ??= new()).Add(
-						new ColumnAttribute()
-						{
-							Name = storeObjectId != null ? prop.GetColumnName(storeObjectId.Value) : null,
-							Length = prop.GetMaxLength() ?? 0,
-							CanBeNull = prop.IsNullable,
-							DbType = prop.GetColumnType(),
-							DataType = dataType,
-							IsPrimaryKey = isPrimaryKey,
-							PrimaryKeyOrder = primaryKeyOrder,
-							IsIdentity = isIdentity,
-							IsDiscriminator = discriminator == prop,
-							SkipOnInsert = skipOnInsert,
-							SkipOnUpdate = skipOnUpdate
-						}
-					);
+					var ca = new ColumnAttribute()
+					{
+						Name = storeObjectId != null ? prop.GetColumnName(storeObjectId.Value) : null,
+						CanBeNull = prop.IsNullable,
+						DbType = prop.GetColumnType(),
+						DataType = dataType,
+						IsPrimaryKey = isPrimaryKey,
+						PrimaryKeyOrder = primaryKeyOrder,
+						IsIdentity = isIdentity,
+						IsDiscriminator = discriminator == prop,
+						SkipOnInsert = skipOnInsert,
+						SkipOnUpdate = skipOnUpdate
+					};
+
+					var maxLen = prop.GetMaxLength();
+					if (maxLen != null)
+						ca.Length = maxLen.Value;
+
+					(result ??= new()).Add(ca);
 
 					// ValueConverterAttribute
 					var converter = prop.GetValueConverter();

Tests/LinqToDB.EntityFrameworkCore.BaseTests/Models/ForMapping/ForMappingContextBase.cs

@@ -12,6 +12,7 @@ protected ForMappingContextBase(DbContextOptions options) : base(options)
 		public DbSet<NoIdentity> NoIdentity { get; set; } = null!;
 		public DbSet<UIntTable> UIntTable { get; set; } = null!;
 		public DbSet<StringTypes> StringTypes { get; set; } = null!;
+		public DbSet<TypesTable> Types { get; set; } = null!;
 
 		public DbSet<WithDuplicateProperties> WithDuplicateProperties { get; set; } = null!;
 

Tests/LinqToDB.EntityFrameworkCore.BaseTests/Models/ForMapping/TypesTable.cs

@@ -0,0 +1,16 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+
+namespace LinqToDB.EntityFrameworkCore.BaseTests.Models.ForMapping
+{
+	public class TypesTable
+	{
+		[Key]
+		public int Id { get; set; }
+
+		public DateTime? DateTime { get; set; }
+		public string? String { get; set; }
+
+		// add more if needed for tests
+	}
+}

Tests/LinqToDB.EntityFrameworkCore.SqlServer.Tests/ForMappingTests.cs

@@ -54,6 +54,19 @@ public void TestStringMappings()
 			}
 		}
 
+		[Test(Description = "https://github.com/linq2db/linq2db.EntityFrameworkCore/issues/349")]
+		public void TestColumnLengthMappings()
+		{
+			using (var db = CreateContext())
+			{
+				var ms = LinqToDBForEFTools.GetMappingSchema(db.Model, db, null);
+				var ed = ms.GetEntityDescriptor(typeof(TypesTable));
+
+				ed.Columns.First(c => c.MemberName == nameof(TypesTable.DateTime)).Length.Should().BeNull();
+				ed.Columns.First(c => c.MemberName == nameof(TypesTable.String)).Length.Should().Be(100);
+			}
+		}
+
 		[Test]
 		public void TestDialectUse()
 		{

Tests/LinqToDB.EntityFrameworkCore.SqlServer.Tests/Models/ForMapping/ForMappingContext.cs

@@ -32,7 +32,13 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 					b.Property(e => e.UnicodeString).HasMaxLength(50).IsUnicode();
 				}
 			);
-			
+
+			modelBuilder.Entity<TypesTable>(b =>
+			{
+				b.Property(e => e.DateTime);
+				b.Property(e => e.String).HasMaxLength(100);
+			});
+
 			modelBuilder.Entity<WithInheritance>(b =>
 			{
 				b.HasDiscriminator(x => x.Discriminator);