[英]AutoMapper: Mapping between a IDataReader and DTO object
我有一个DataReader,其中包含存储过程的结果。 列的命名约定使用下划线表示空格。
我已经能够在IDataReader和IEnumerable之间成功映射,但前提是字段完全匹配。 我不想使用存储过程中的命名约定来规定我在对象中命名字段的方式。 在数据库方面也是如此。 我认为我不会在DBA上成功执行Pascal Case。
我想避免必须对需要映射的每个字段使用ForMember()。 那会破坏使用AutoMapper的目的。
我找到了关于该主题的先前文章 ,在测试中已将其用作参考。 我无法获得正确的配置/映射才能成功通过测试。 我希望有人可以提供帮助。
public class DataReaderTests
{
private DTOObject _result;
private IDataReader _dataReader;
protected override void Establish_context()
{
Mapper.Initialize(cfg =>
{
cfg.SourceMemberNamingConvention = new LowerUnderscoreNamingConvention();
cfg.DestinationMemberNamingConvention = new PascalCaseNamingConvention();
cfg.CreateMap<IDataReader, IEnumerable<DTOObject>>();
});
_dataReader = new DataBuilder().BuildDataReader();
_result = Mapper.Map<IDataReader, IEnumerable<DTOObject>>(_dataReader).FirstOrDefault();
}
[Test]
public void Then_a_column_containing_phone_number_should_be_read()
{
Assert.That(_result.PhoneNumber, Is.EqualTo(_dataReader[FieldName.PhoneNumber]));
}
}
public class DataBuilder
{
public IDataReader BuildDataReader()
{
var resultData = new DataTable();
resultData.Columns.Add(FieldName.PhoneNumber, typeof(string));
var resultDataRow = resultData.NewRow();
resultDataRow[FieldName.PhoneNumber] = "111-222-3333";
resultData.Rows.Add(resultDataRow);
return resultData.CreateDataReader();
}
}
internal class FieldName
{
public const String Id = "id";
public const String Name = "name";
public const String PhoneNumber = "phone_number";
public const String CreateDate = "create_date";
}
public class DTOObject
{
public Guid Id { get; set; }
public string Name { get; set; }
public string PhoneNumber { get; set; }
public DateTime CreatedDate { get; set; }
}
我们已经编写了自定义属性来实现此目的。 我们借助反射进行映射分配,这是一些示例代码。
应用于业务对象属性以进行对话映射的属性。
/// <summary>
/// Holds mapping information between business objects properties and database table fields.
/// </summary>
[global::System.AttributeUsage(AttributeTargets.Property, Inherited = true, AllowMultiple = false)]
public sealed class DataFieldMappingAttribute : Attribute
{
/// <summary>
/// Initializes a new instance of the DataFieldMappingAttribute class.
/// </summary>
/// <param name="fieldName">Name of the Field in Database Table that the business object properties maps to.</param>
public DataFieldMappingAttribute(string fieldName)
{
this.MappedField = fieldName;
}
/// <summary>
/// Gets or Sets the mapped Database Table Field.
/// </summary>
public string MappedField
{
get;
private set;
}
}
在我的应用程序中,样本业务对象看起来像这样。
User.cs
[TableMapping("Users")]
public class User : EntityBase
{
#region Constructor(s)
public AppUser()
{
BookCollection = new BookCollection();
}
#endregion
#region Properties
#region Default Properties - Direct Field Mapping using DataFieldMappingAttribute
private System.Int32 _UserId;
private System.String _FirstName;
private System.String _LastName;
private System.String _UserName;
private System.Boolean _IsActive;
[DataFieldMapping("UserID")]
[DataObjectFieldAttribute(true, true, false)]
[NotNullOrEmpty(Message = "UserID From Users Table Is Required.")]
public override int Id
{
get
{
return _UserId;
}
set
{
_UserId = value;
}
}
[DataFieldMapping("UserName")]
[Searchable]
[NotNullOrEmpty(Message = "Username Is Required.")]
public string UserName
{
get
{
return _UserName;
}
set
{
_UserName = value;
}
}
[DataFieldMapping("FirstName")]
[Searchable]
public string FirstName
{
get
{
return _FirstName;
}
set
{
_FirstName = value;
}
}
[DataFieldMapping("LastName")]
[Searchable]
public string LastName
{
get
{
return _LastName;
}
set
{
_LastName = value;
}
}
[DataFieldMapping("IsActive")]
public bool IsActive
{
get
{
return _IsActive;
}
set
{
_IsActive = value;
}
}
#region One-To-Many Mappings
public BookCollection Books { get; set; }
#endregion
#region Derived Properties
public string FullName { get { return this.FirstName + " " + this.LastName; } }
#endregion
#endregion
public override bool Validate()
{
bool baseValid = base.Validate();
bool localValid = Books.Validate();
return baseValid && localValid;
}
}
BookCollection.cs
/// <summary>
/// The BookCollection class is designed to work with lists of instances of Book.
/// </summary>
public class BookCollection : EntityCollectionBase<Book>
{
/// <summary>
/// Initializes a new instance of the BookCollection class.
/// </summary>
public BookCollection()
{
}
/// <summary>
/// Initializes a new instance of the BookCollection class.
/// </summary>
public BookCollection (IList<Book> initialList)
: base(initialList)
{
}
}
这是从DataRow到BusinessObject的转换方法,该方法包装在Extension方法的调用周围。
/// <summary>
/// Transforms DataRow into business object.
/// </summary>
/// <typeparam name="TEntity">A type that inherits EntityBase.</typeparam>
/// <typeparam name="TDataRow">A type that inherits DataRow.</typeparam>
/// <param name="dataRow">DataRow object which is transformed from business object.</param>
/// <param name="entity">business object which is transformed into DataRow object.</param>
public static void TransformDataRowToEntity<TEntity, TDataRow>(ref TDataRow dataRow, ref TEntity entity)
where TDataRow : DataRow
where TEntity : EntityBase
{
IQueryable<DataField> entityFields = entity.GetDataFields();
foreach (var entityField in entityFields)
{
if (dataRow[entityField.DataFieldMapping.MappedField] is System.DBNull)
{
entityField.Property.SetValue(entity, null, null);
}
else
{
if (entityField.Property.GetType().IsEnum)
{
Type enumType = entityField.Property.GetType();
EnumConverter enumConverter = new EnumConverter(enumType);
object enumValue = enumConverter.ConvertFrom(dataRow[entityField.DataFieldMapping.MappedField]);
entityField.Property.SetValue(entity, enumValue, null);
}
else
{
entityField.Property.SetValue(entity, dataRow[entityField.DataFieldMapping.MappedField], null);
}
}
}
}
我下载了AutoMapper源代码,并且可以进行一些调试。 我必须更改DataReaderMapper.cs中的CreateBuilder方法以使测试通过。
private static Build CreateBuilder(Type destinationType, IDataRecord dataRecord)
{
var method = new DynamicMethod("DynamicCreate", destinationType, new[] { typeof(IDataRecord) }, destinationType, true);
var generator = method.GetILGenerator();
var result = generator.DeclareLocal(destinationType);
generator.Emit(OpCodes.Newobj, destinationType.GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Stloc, result);
for (var i = 0; i < dataRecord.FieldCount; i++)
{
var propertyInfo = destinationType.GetProperty(ConvertLowerUnderscoreNamingToPascalNaming(dataRecord.GetName(i)));
var endIfLabel = generator.DefineLabel();
if (propertyInfo != null && propertyInfo.GetSetMethod(true) != null)
{
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, isDBNullMethod);
generator.Emit(OpCodes.Brtrue, endIfLabel);
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, getValueMethod);
generator.Emit(OpCodes.Unbox_Any, dataRecord.GetFieldType(i));
generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod(true));
generator.MarkLabel(endIfLabel);
}
}
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ret);
return (Build)method.CreateDelegate(typeof(Build));
}
//TODO: refactor to use INamingConvetion and resolve with RegEx pattern
private static string ConvertLowerUnderscoreNamingToPascalNaming(string original)
{
var LowerOriginal = original.ToLower();
string[] tokens = LowerOriginal.Split('_');
string converted = "";
foreach (var token in tokens)
converted += token.Substring(0, 1).ToUpper() + token.Substring(1);
return converted;
}
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