Expression<Func<TDto, IEnumerable<C>>>

Question

我使用automapper 把Expression<Func<TDto, IEnumerable<C>>> 转<Expression<Func<TEntity, IEnumerable<C>>> 报 System.InvalidCastException: 无法将类型为“System.Linq.Expressions.Expression`1[System.Func`2[meixiaohu.Entities.MongoDB.Order,System.Collections.Generic.List`1[meixiaohu.Entities.MongoDB.ChildOrder]]]”的对象强制转换为类型“System.Linq.Expressions.Expression`1[System.Func`2[meixiaohu.Entities.MongoDB.Order,System.Collections.Generic.IEnumerable`1

 

 

转换代码

  public async virtual Task Pull<C>(string id, Expression<Func<TDto, IEnumerable<C>>> field, Expression<Func<C, bool>> expression)
        {
            var entityField = Mapper.Map<Expression<Func<TEntity, IEnumerable<C>>>>(field);

}

Answer 1

Expression是表达式树解析成SQL的，Fun是泛型委托，你最终的实际结果应该是IEnumerable，你应该去掉表达式树和泛型委托，你那样做AutoMapper无法解析！