修复可空枚举导入异常

src/Magicodes.ExporterAndImporter.Excel/Utility/ImportHelper.cs

@@ -1251,6 +1251,12 @@ protected virtual void ParseData(ExcelPackage excelPackage)
                                     SetValue(cell, dataItem, propertyInfo, value);
                                     continue;
                                 }
+                                // 如果是可空枚举,选中空白项传入"",处理成null,不然会出现SetValue会报错
+                                else if (propertyInfo.PropertyType.IsNullable() && propertyInfo.PropertyType.GetNullableUnderlyingType().IsEnum)
+                                {
+                                    SetValue(cell,dataItem,propertyInfo,null);
+                                    continue;
+                                }
                             }
 
                             if (propertyInfo.PropertyType.IsEnum

src/Magicodes.ExporterAndImporter.Tests/ExcelImporter_Tests.cs

@@ -1210,5 +1210,12 @@ public async Task Issue377_Test()
             import.HasError.ShouldBeFalse();
             import.Data.Count.ShouldBe(3);
         }
+        [Fact(DisplayName = "可空枚举类型导入测试")]
+        public async Task NullableEnum_Test()
+        {
+            var filePath = Path.Combine(Directory.GetCurrentDirectory(), "TestFiles", "Import", "NullableEnum.xlsx");
+            var import = await Importer.Import<NullableEnumTestImportDto>(filePath);
+            import.HasError.ShouldBeFalse();
+        }
     }
 }

src/Magicodes.ExporterAndImporter.Tests/Models/Import/NullableEnumTestImportDto.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+using Magicodes.ExporterAndImporter.Core;
+
+namespace Magicodes.IE.Tests.Models.Import;
+/// <summary>
+/// 可空枚举问题测试
+/// </summary>
+public class NullableEnumTestImportDto
+{
+    /// <summary>
+    /// 编号
+    /// </summary>
+    [ImporterHeader(Name = "编号")]
+    public string No { get; set; }
+    /// <summary>
+    /// 等级
+    /// </summary>
+    [ImporterHeader(Name = "等级")]
+    public EnumTest? Level { get; set; }
+}
+public enum EnumTest
+{
+    A,
+    B,
+}