dapper 自定义数据库字段和代码中Model字段不一致时候的mapping方法

namespace YourNamespace

{

    /// <summary>

    /// Uses the Name value of the ColumnAttribute specified, otherwise maps as usual.

    /// </summary>

    /// <typeparam name="T">The type of the object that this mapper applies to.</typeparam>

    public class ColumnAttributeTypeMapper<T> : FallbackTypeMapper

    {

        public ColumnAttributeTypeMapper()

            : base(new SqlMapper.ITypeMap[]

                {

                    new CustomPropertyTypeMap(

                       typeof(T),

                       (type, columnName) =>

                           type.GetProperties().FirstOrDefault(prop =>

                               prop.GetCustomAttributes(false)

                                   .OfType<ColumnMappingAttribute>()

                                   .Any(attr => attr.Name == columnName)

                               )

                       ),

                    new DefaultTypeMap(typeof(T))

                })

        {

        }

    }

    

  [AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]

    public class ColumnMappingAttribute : Attribute

    {

        public string Name { get; set; }

    }

 

  public class FallbackTypeMapper : SqlMapper.ITypeMap

    {

        private readonly IEnumerable<SqlMapper.ITypeMap> _mappers;

 

        public FallbackTypeMapper(IEnumerable<SqlMapper.ITypeMap> mappers)

        {

            _mappers = mappers;

        }

 

 

        public ConstructorInfo FindConstructor(string[] names, Type[] types)

        {

            foreach (var mapper in _mappers)

            {

                try

                {

                    ConstructorInfo result = mapper.FindConstructor(names, types);

                    if (result != null)

                    {

                        return result;

                    }

                }

                catch (NotImplementedException)

                {

                }

            }

            return null;

        }

 

        public SqlMapper.IMemberMap GetConstructorParameter(ConstructorInfo constructor, string columnName)

        {

            foreach (var mapper in _mappers)

            {

                try

                {

                    var result = mapper.GetConstructorParameter(constructor, columnName);

                    if (result != null)

                    {

                        return result;

                    }

                }

                catch (NotImplementedException)

                {

                }

            }

            return null;

        }

 

        public SqlMapper.IMemberMap GetMember(string columnName)

        {

            foreach (var mapper in _mappers)

            {

                try

                {

                    var result = mapper.GetMember(columnName);

                    if (result != null)

                    {

                        return result;

                    }

                }

                catch (NotImplementedException)

                {

                }

            }

            return null;

        }

    }

  

}

public static IEnumerable LoadWithCustomMapping()

{

    using (var conn = OpenDBConnection())

    {

        Dapper.SqlMapper.SetTypeMap(typeof(MyArea), new ColumnAttributeTypeMapper());

        return conn.Query("SELECT TOP 10 CAID,CAName,En FROM CityArea");

    }

}