帮助声明LINQ to EF查询 [英] help with declaration of LINQ to EF query

问题描述

大家好，谁可以帮助我定义LINQ查询.

我有一个简单的实体:

Hi guys, who can help me with definition of LINQ query.

I''ve got a simple entity:

public class PhysicianInfo2
    {
        public PhysicianInfo2()
        {
            foreach (System.Reflection.PropertyInfo info in this.GetType().GetProperties())
            {
                if (info.PropertyType == typeof(List<string>))
                {
                    info.SetValue(this, new List<string>(), null);
                    continue;
                }
                info.SetValue(this, string.Empty, null);
            }
        }

        public string NPI { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string MiddleName { get; set; }
        public string Prefix { get; set; }
        public string Suffix { get; set; }
        public string Email { get; set; }

        //------- can be a list
        public string Speciality { get; set; }  //(this could be a list)
        public string Institution { get; set; } //(this could be a list)
        public string Status { get; set; }      //(online, offline, busy)
}

和以下查询列表:

and query list below:

var item2 = (from item in _context.Physician.Include("PersonalInfo")

                             let specialities = (from spec in _context.PhysicianSpecialty.Include("Speciality")
                                                 where spec.PhysicianID == item.PhysicianID
                                                 select spec.Specialty)

                             select new Models.PhysicianInfo2()
                             {
                                 NPI = item.NPI,
                                 Email = item.PersonalInfo.Email,
                                 FirstName = item.PersonalInfo.FirstName,
                                 LastName = item.PersonalInfo.LastName,
                                 MiddleName = item.PersonalInfo.MiddleName,
                                 Prefix = item.PersonalInfo.Prefix,
                                 Suffix = item.PersonalInfo.Suffix,
                                 Speciality = (from subItem in specialities
                                               select subItem.Name).Aggregate((a, b) => string.Format("{0}, {1}", a, b)),
                                 Institution = string.Empty
                             });

                count = item2.AsEnumerable().Count();

每当我编译并调用查询时，都会收到错误消息:

在类型"System.Data.Entity.Infrastructure.DbQuery`1 [PhysicianRegistry.Data.]中声明的方法"System.Data.Entity.Infrastructure.DbQuery`1 [PhysicianRegistry.Data.PhysicianSpecialty] Include(System.String)". PhysicianSpecialty]''不能用类型为``System.Data.Objects.ObjectQuery`1 [PhysicianRegistry.Data.PhysicianSpecialty]''
的实例调用

谁可以解决我的问题?

Whenever i compile and invoke a query, i receive an error :

Method ''System.Data.Entity.Infrastructure.DbQuery`1[PhysicianRegistry.Data.PhysicianSpecialty] Include(System.String)'' declared on type ''System.Data.Entity.Infrastructure.DbQuery`1[PhysicianRegistry.Data.PhysicianSpecialty]'' cannot be called with instance of type ''System.Data.Objects.ObjectQuery`1[PhysicianRegistry.Data.PhysicianSpecialty]''


Who can resolve my issue?

推荐答案

我自己解决了此问题.

导致其不起作用的主要原因是隐藏在属性的实现中:

i have resolved this issue by myself.

The main reason , why this wont work , hide in realization of property:

public string Speciality { get; set; } 

关于此属性，我将其类型更改为，请参见以下内容:

As concerns this property i have change it type to, see below:

public IEnumerable<string> Specialty { get; set; } </string>

并更改了我的查询:

and changed a bit my query:

var item2 = (from item in _context.Physician.Include("PersonalInfo").Include(x => x.PhysicianSpecialty).Include("PhysicianSpecialty.Speciality")

                             let specialities = (from spec in _context.PhysicianSpecialty
                                                 where spec.PhysicianID == item.PhysicianID
                                                 select spec.Specialty)

                             select new Models.PhysicianInfo2()
                             {
                                 NPI = item.NPI,
                                 Email = item.PersonalInfo.Email,
                                 FirstName = item.PersonalInfo.FirstName,
                                 LastName = item.PersonalInfo.LastName,
                                 MiddleName = item.PersonalInfo.MiddleName,
                                 Prefix = item.PersonalInfo.Prefix,
                                 Suffix = item.PersonalInfo.Suffix,
                                 Specialty = specialities,
                                 Institution = string.Empty
                             });

IEnumerable的字符串表示形式的字符串如下所示:

String representation of IEnumerable of string irepresented like this:

public string SpecialityString 
{ 
get{return Specialty==null?string.empty:Specialty.Aggregate((a, b) =>                    
                                       string.Format("{0}, {1}", a, b));
 }
 }

这篇关于帮助声明LINQ to EF查询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！