AutoMapper6扩展

作者：jianxuanbing
本文为作者原创，转载请注明出处：https://www.cnblogs.com/jianxuanbing/p/7122877.html

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简介

很多时候我们使用AutoMapper的时候，都需要进行一个配置才可以使用Mapper.Map<Source,Target>(entity);。如果不进行配置则会报错。
如果实体过多，有时候会忘记是否有配置，只有运行的时候才会发现这个BUG。

源代码地址

• 源码地址
• 测试案例地址

源代码

该扩展基于AutoMapper 6.x版本，因此需要从Nuget下载相应的包。
该扩展对于Object以及List<T>进行了兼容支持，因此MapTo<TSource,TDestination>()可以直接映射实体与泛型列表。

/// <summary>
/// AutoMapper 对象映射扩展
/// </summary>
public static partial class Extensions
{
    /// <summary>
    /// 同步锁
    /// </summary>
    private static readonly object Sync=new object();

    #region MapTo(将源对象映射到目标对象)

    /// <summary>
    /// 将源对象映射到目标对象
    /// </summary>
    /// <typeparam name="TSource">源类型</typeparam>
    /// <typeparam name="TDestination">目标类型</typeparam>
    /// <param name="source">源对象</param>
    /// <param name="destination">目标对象</param>
    /// <returns></returns>
    public static TDestination MapTo<TSource, TDestination>(this TSource source, TDestination destination)
    {
        return MapTo<TDestination>(source, destination);
    }

    /// <summary>
    /// 将源对象映射到目标对象
    /// </summary>
    /// <typeparam name="TDestination">目标类型</typeparam>
    /// <param name="source">源对象</param>
    /// <returns></returns>
    public static TDestination MapTo<TDestination>(this object source) where TDestination : new()
    {
        return MapTo(source, new TDestination());
    }

    /// <summary>
    /// 将源对象映射到目标对象
    /// </summary>
    /// <typeparam name="TDestination">目标类型</typeparam>
    /// <param name="source">源对象</param>
    /// <param name="destination">目标对象</param>
    /// <returns></returns>
    private static TDestination MapTo<TDestination>(object source, TDestination destination)
    {
        if (source == null)
        {
            throw new ArgumentNullException(nameof(source));
        }
        if (destination == null)
        {
            throw new ArgumentNullException(nameof(destination));
        }
        var sourceType = GetType(source);
        var destinationType = GetType(destination);
        var map = GetMap(sourceType, destinationType);
        if (map != null)
        {
            return Mapper.Map(source, destination);
        }
        lock (Sync)
        {
            map = GetMap(sourceType, destinationType);
            if (map != null)
            {
                return Mapper.Map(source, destination);
            }
            InitMaps(sourceType, destinationType);
        }
        return Mapper.Map(source, destination);
    }

    /// <summary>
    /// 获取映射配置
    /// </summary>
    /// <param name="sourceType">源类型</param>
    /// <param name="destinationType">目标类型</param>
    /// <returns></returns>
    private static TypeMap GetMap(Type sourceType, Type destinationType)
    {
        try
        {
            return Mapper.Configuration.FindTypeMapFor(sourceType, destinationType);
        }
        catch (InvalidOperationException)
        {
            lock (Sync)
            {
                try
                {
                    return Mapper.Configuration.FindTypeMapFor(sourceType, destinationType);
                }
                catch (InvalidOperationException)
                {
                    InitMaps(sourceType, destinationType);
                }
                return Mapper.Configuration.FindTypeMapFor(sourceType, destinationType);
            }
        }
    }

    /// <summary>
    /// 获取类型
    /// </summary>
    /// <param name="obj">对象</param>
    /// <returns></returns>
    private static Type GetType(object obj)
    {
        var type = obj.GetType();
        if (obj is System.Collections.IEnumerable == false)
        {
            return type;
        }
        if (type.IsArray)
        {
            return type.GetElementType();
        }
        var genericArgumentsTypes = type.GetTypeInfo().GetGenericArguments();
        if (genericArgumentsTypes == null || genericArgumentsTypes.Length == 0)
        {
            throw new ArgumentException("泛型类型参数不能为空");
        }
        return genericArgumentsTypes[0];
    }

    /// <summary>
    /// 初始化映射配置
    /// </summary>
    /// <param name="sourceType">源类型</param>
    /// <param name="destinationType">目标类型</param>
    private static void InitMaps(Type sourceType, Type destinationType)
    {
        try
        {
            var maps = Mapper.Configuration.GetAllTypeMaps();
            Mapper.Initialize(config =>
            {
                ClearConfig();
                foreach (var item in maps)
                {
                    config.CreateMap(item.SourceType, item.DestinationType);
                }
                config.CreateMap(sourceType, destinationType);
            });
        }
        catch (InvalidOperationException)
        {
            Mapper.Initialize(config =>
            {
                config.CreateMap(sourceType, destinationType);
            });
        }
    }

    /// <summary>
    /// 清空配置
    /// </summary>
    private static void ClearConfig()
    {
        var typeMapper = typeof(Mapper).GetTypeInfo();
        var configuration = typeMapper.GetDeclaredField("_configuration");
        configuration.SetValue(null, null, BindingFlags.Static, null, CultureInfo.CurrentCulture);
    }

    #endregion

    #region MapToList(将源集合映射到目标列表)

    /// <summary>
    /// 将源集合映射到目标列表
    /// </summary>
    /// <typeparam name="TDestination">目标元素类型，范例：Sample，不用加List</typeparam>
    /// <param name="source">源集合</param>
    /// <returns></returns>
    public static List<TDestination> MapToList<TDestination>(this System.Collections.IEnumerable source)
    {
        return MapTo<List<TDestination>>(source);
    }

    #endregion
}

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