没有 AutoMap 之前我是怎么将 DataModel 转换为 ViewModel

很多年前，刚开始接触到 ViewModel 概念的时候，将 DataModel 赋值给 ViewModel 的时候通常会这样做：

                Id = x.Id,
                ParentId = x.ParentId,
                Name = x.Name,
                Code = x.Code,
                ChildCode = x.ChildCode,
                Area = x.Area,
                AuditId = x.AuditId,
                AuditName = x.AuditName,
                AuditTime = x.AuditTime,
                IsBIM = x.IsBIM,
                Status = x.Status,
                SoftDeleted = x.SoftDeleted,

                ConstructionUnit = x.ConstructionUnit,
                ConstructionUnitId = x.ConstructionUnitId,
                BuilderUnitNames = x.BuilderUnitNames,
                BuilderUnitIds = x.BuilderUnitIds,
                SupervisionUnit = x.SupervisionUnit,
                SupervisionUnitId = x.SupervisionUnitId,
                TestingUnit = x.TestingUnit,
                TestingUnitId = x.TestingUnitId,
                PremixedSupplier = x.PremixedSupplier,
                PremixedSupplierId = x.PremixedSupplierId,
                DesignUnit = x.DesignUnit,
                DesignUnitId = x.DesignUnitId,
                SurveyUnit = x.SurveyUnit,
                SurveyUnitId = x.SurveyUnitId,

                Address = x.Address,
                Location = x.Location,
                Image = x.Image,
                ImageUploadTime = x.ImageUploadTime,
                CreatedTime = x.CreatedTime,

上面的代码逻辑都是相同的，有多少字段都需要单独写出来。如果有新增或在修改删除字段的情况，还需要一一找到再做调整。所以当时就在网上找到了下面这段代码，实现的功能主要是将两个实体中字段名称相同，且类型相同的字段自动赋值，代码如下：

    public static class ConvertHelper
    {
        /// <summary>
        /// 两个相似实体转换
        /// </summary>
        /// <typeparam name="S">源实体</typeparam>
        /// <typeparam name="T">赋值实体</typeparam>
        /// <param name="source">源实体值</param>
        /// <returns></returns>
        public static T Merge<S, T>(this S source) where T : new()
        {
            if (source == null) return default(T);

            var propertiesT = typeof(S).GetProperties(BindingFlags.Instance | BindingFlags.Public);
            var propertiesL = typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public);

            var entity = new T();
            foreach (PropertyInfo itemL in propertiesL)
            {
                foreach (PropertyInfo itemT in propertiesT)
                {
                    if (itemL.Name != itemT.Name || itemL.PropertyType != itemT.PropertyType) continue;

                    var value = itemT.GetValue(source, null);
                    itemL.SetValue(entity, value, null);
                    break;
                }
            }
            return entity;
        }
    }

有了这个方法后，上面字段赋值的代码就可以用一行代码完成。从工作量上来看，这个代码是为我剩了不少。关于性能方面的问题，就暂时不在这里讨论。后面有机会再分享基于这个版本升级为带缓存的版本。

var project = projectDataModel.Merge<ProjectDataModel, ProjectViewModel>();