/// <summary>
/// 需要同时加载外键
/// </summary>
/// <typeparam name="TFKEntity"></typeparam>
/// <param name="fkEntityExp">
/// 需要加载的外键实体属性表达式
/// </param>
/// <returns></returns>
public PropertySelector <TFKEntity> LoadFK <TFKEntity>(Expression <Func <TEntity, TFKEntity> > fkEntityExp)
where TFKEntity : Entity
{
var entityPropertyName = GetPropertyName(fkEntityExp);
var propertyName = entityPropertyName + Entity.IdProperty.Name;
var entityInfo = CommonModel.Entities.Get(typeof(TEntity));
var propertyInfo = entityInfo.EntityProperties.FirstOrDefault(p => p.Name == propertyName);
//构造一个临时代理方法，实现：TEntity.EntityProperty = TFKEntity
var pE = Expression.Parameter(typeof(TEntity), "e");
var pEFK = Expression.Parameter(typeof(TFKEntity), "efk");
var propertyExp = Expression.Property(pE, entityPropertyName);
var body = Expression.Assign(propertyExp, pEFK);
var result = Expression.Lambda <Action <TEntity, TFKEntity> >(body, pE, pEFK);
var fkSetter = result.Compile();
var option = new LoadOptionItem(propertyInfo, (e, eFK) => fkSetter(e as TEntity, eFK as TFKEntity));
//避免循环
if (this.InnerDescriptor.Items.Any(i => i.OwnerType == option.PropertyEntityType))
{
throw new InvalidOperationException("有循环的实体设置。");
}
this.InnerDescriptor.AddItem(option);
return(new PropertySelector <TFKEntity>(this.InnerDescriptor));
}
/// <summary>
/// 追加一个聚合加载选项
/// </summary>
/// <param name="item"></param>
internal void AddItem(LoadOptionItem item)
{
this._items.AddLast(item);
}