help with declaration of LINQ to EF query

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

I've got a simple entity:

C#

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)
}

and query list below:

C#

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();

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?

Posted 30-Jul-12 2:21am

Oleksandr Kulchytskyi

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Oleksandr Kulchytskyi 30-Jul-12 8:28am

partially, i resolved my issue , but i encountered with another problem related to aggregate exception

Fixed query looks like below:

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,
Speciality = (from subItem in specialities
select subItem.Name).Aggregate((a, b) => string.Format("{0}, {1}", a, b)),
Institution = string.Empty
});

but error appears:

LINQ to Entities does not recognize the method 'System.String Aggregate[String](System.Linq.IQueryable`1[System.String], System.Linq.Expressions.Expression`1[System.Func`3[System.String,System.String,System.String]])' method, and this method cannot be translated into a store expression.

Oleksandr Kulchytskyi 30-Jul-12 8:31am

Models.PhysicianInfo2.Speciality property that, represents physician info specialties, it could consists from one or more items.

1 solution

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Oleksandr Kulchytskyi · Accepted Answer · 2012-08-01T02:40:00

i have resolved this issue by myself.

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

C#

public string Speciality { get; set; }

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

C#

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

and changed a bit my query:

C#

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
                             });

String representation of IEnumerable of string irepresented like this:

C#

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