Develop Reference

How to execute RawSql against the context

I currently have a project that I'm working on, which has a database connected to it. In said database I need to query some tables that don't have a relationship. I need to get a specific set of data in order to display it on my user interface. However I need to be able to reference the returned data put it into a list and convert it into json. I have a stored procedure that needs to just be executed against the context because it's retrieving data from many different tables.
I've tried using ExecuteSqlCommand but that doesn't work, because it returns -1 and can't put it into a list.
I've tried using linq to select the columns I want however it's really messy and I cannot retrieve the data as easily.
I've tried using FromSql, however that needs a model to execute against the context which is exactly what I don't want.
public string GetUserSessions(Guid memberId)
{
string sql = $"EXECUTE dbo.GetUserTrackByMemberID #p0";
var session = _context.Database.ExecuteSqlCommand(sql, memberId);
var json = JsonConvert.SerializeObject(session);
return json;
}
This is the ExecuteSqlCommand example, this returns -1 and cannot be put into a list as there will be more than one session.
public string GetUserSessions(Guid memberId)
{
var session = _context.MemberSession.Where(ms => ms.MemberId == memberId).Select(s => new Session() { SessionId =
s.SessionId, EventId = s.Session.EventId, CarCategory = s.Session.CarCategory, AirTemp = s.Session.AirTemp,
TrackTemp = s.Session.TrackTemp, Weather = s.Session.Weather, NumberOfLaps = s.Session.NumberOfLaps, SessionLength = s.Session.SessionLength,
Event = new Event() { EventId = s.Session.Event.EventId, TrackId = s.Session.Event.TrackId, Name = s.Session.Event.Name, NumberOfSessions =
s.Session.Event.NumberOfSessions, DateStart = s.Session.Event.DateStart, DateFinish = s.Session.Event.DateFinish, TyreSet = s.Session.Event.TyreSet,
Track = new Track() { TrackId = s.Session.Event.Track.TrackId, Name = s.Session.Event.Track.Name, Location = s.Session.Event.Track.Location, TrackLength
= s.Session.Event.Track.TrackLength, NumberOfCorners = s.Session.Event.Track.NumberOfCorners} } });
var json = JsonConvert.SerializeObject(session);
return json;
}
This is using Linq, however it's really messy and I feel there's probably a better way to do this, and then when retrieving the data from json it's a lot bigger pain.
public string GetUserSessions(Guid memberId)
{
var session = _context.MemberSession.FromSql($"EXECUTE dbo.GetUserSessionByMemberID {memberId}").ToList();
var json = JsonConvert.SerializeObject(session);
return json;
}
This is the ideal way I would like to do it, however since I'm using the MemberSession model it will only retrieve that data from the stored procedure which is in the MemberSession table, however I want data that is in other tables as well....
public string GetUserSessions(Guid memberId)
{
var session = _context.MemberSession.Where(ms => ms.MemberId == memberId).Include("Session").Include("Event").ToList();
var json = JsonConvert.SerializeObject(session);
return json;
}
I tried this way but because the Event table has no reference / relationship to MemberSession it returns an error.
As I've previously stated in the RawSql example I'm only getting the table data that is in the MemberSession table, no other tables.
There are no error messages.

using (var context = new DBEntities())
{
string query = $"Exec [dbo].[YOUR_SP]";
List<ResponseList> obj = context.Database.SqlQuery<ResponseList>(query).ToList();
string JSONString = JsonConvert.SerializeObject(obj);
}

Insert rows using Linq

Can anyone tell where I make a mistake ? :( I want to insert a row using this. It's just not working. I also tried to use "context.SaveChanges();" but nothing changed. No insert at all, and no exception.
public List<string> Add_Address(string address, int selected_item)
{
List<string> list = new List<string>();
using(var context = new RSS_Reader_Database())
{
Address Address = new Address();
Category_Address Category_Address = new Category_Address();
Address.URL = address.ToString();
int max_id = Convert.ToInt32(context.Addresses.OrderByDescending(t => t.ID_Address).FirstOrDefault());
Category_Address.ID_Address = max_id;
Category_Address.ID_Category = selected_item+1;
var select_query = from t in context.Addresses select t.URL;
foreach (var element in select_query)
{
list.Add(element);
}
}
return list;
}
Edit: Following all Your advices, I made something that works. Looking at this code above, I have no idea what I was trying to do yesterday. Thanks a lot.
public List<string> Add_Address(string address, int selected_item)
{
List<string> list = new List<string>();
using(var context = new RSS_Reader_Database())
{
Address Address = new Address() { URL = address };
context.Addresses.Add(Address);
context.SaveChanges();
int max_id = context.Addresses.Max(u => u.ID_Address);
Category_Address Category_Address = new Category_Address() { ID_Address = max_id, ID_Category = selected_item + 1 };
context.Categories_Addresses.Add(Category_Address);
context.SaveChanges();
var query = from t in context.Addresses
select t.URL;
var data = query.ToList();
foreach (var element in data)
{
list.Add(element);
}
}
return list;
}

Saving with Entity Framework generally works like this. Using your above code as a starting point.
using(var context = new RSS_Reader_Database())
{
Address address = new Address();
// Set address properties
context.Addresses.Add(address);
context.SaveChanges();
}
You need to add the object to the DbSet<T> where T is the type of the entity that is defined on the DbContext. You then need to call SaveChanges() on the context.
I would suggest reading this. It is an easy to follow introduction to Entity Framework.

Not sure exactly what you are trying to do.
But if you are expecting to insert the data by the list.Add(element); command it won't work.
If you are planning to insert data into the same DB, you need to use one property from the context to represent the List collection add a new element on this property.
Something like:
context.Lists.Add(element);

if you want retrieve data, you should not call SaveChanges() !,
try get all values from one query like this:
List<string> select_query = (from t in context.Addresses select t.URL).ToList();

How can I edit or add to a particular field without pull the all object

How I can do just this ( a.myFavorits.Add()) without pulling the all object to var a , because a has a lot of data, and I don't want to pull all a object, but I can't find a way do do it.
I want to do the lambada and the linq without return something but linq is always return something
public static void addFavorits(long f,long idUser)
{
using (var db = dataBase())
{
// here i pull object user from users table
var a = db.users.Where(c => c.id == idUser).SingleOrDefault();
// here i adding to the object field myFavorits new value
//myFavorits is also a table of entitys that connected to user object
a.myFavorits.Add(new BE.FavoritsUsersLong { myLong = f });
db.SaveChanges();
}
}
I thought to do something like this but i dont know how to set the field users_TableId that is the key that connect the 2 tables
public static void addFavorits(long favoritId,long idUser)
{
using (var db = dataBase())
{
db.favoritsUsersLong.Add(new BE.FavoritsUsersLong {myLong = favoritId}
/*,users_TableId =idUser*/);
db.SaveChanges();
}
}

Here's a concrete example that does what you want. In this example, only the Name of a Company is modified and saved. Or an item is added to one of its collections.
var cmp = new Company{ CmpId = 1, Name = "Cmp1" }; // CmpId is the primary key
db.Companies.Attach(cmp);
db.Entry(cmp).Property(c => c.Name).IsModified = true;
// Or add an entity to a collection:
cmp.Users = new[] {new User { Name = "a1", PassWord = "a1" } };
try
{
db.Configuration.ValidateOnSaveEnabled = false;
db.SaveChanges();
}
finally
{
db.Configuration.ValidateOnSaveEnabled = true;
}
Result in SQL:
DECLARE #0 VarChar(30) = 'Cmp1'
DECLARE #1 Int = 1
UPDATE [dbo].[Company]
SET [Name] = #0
WHERE ([CmpId] = #1)
There are a few things to note here:
Obviously you need to know the Id of the entity you want to modify.
The object you create is called a stub entity, which is an incomplete entity. When you try to save such an entity, EF is very likely to complain about null values in required properties. That's why almost certain you'd have to disable validation (temporarily, or, better, dispose the context immediately).
If you want to add an item to a collection, you should leave validation enabled, because you'd want to know for sure that the new entity is valid. So you shouldn't mix these two ways to use a stub entity.
If you often need roughly the same small part of your entity you may consider table splitting.

I'm guessing this is what you want? I don't see you 'editting' I only see you adding.
using (var db = dataBase())
{
var a = new user();
....
//set properties etc..
...
a.myFavorits.Add(new BE.FavoritsUsersLong { myLong = f });
db.users.Add(a);
db.SaveChanges();
}

Reusing projections in queries, the part after "select new"

In my ASP.NET MVC Application, I have many actions that return JSONs.
In these JSONs, some sub-structures are repeated.
For example
ajax: "/Bands/Members" is supposed to return the members of a band, which are all musicians
ajax: "/Musicians/All" is supposed to return all the musicians on the system
ajax: "/Musicians/Search" is supposed to return all the musicians that match something
etc...
Here I show (1):
public JsonResult Members(long musicBandId)
{
MusicBand b = db.MusicBands.SingleOrDefault(b => b.MusicBandId == musicBandId);
if (b == null)
return null;
return Json(new
{
error = false,
message = "",
persons = from m in b.Members select new
{
musicianId = p.MusicianId,
name = m.Name,
instrument = new
{
instrumentId = m.instrument.InstrumentId,
model = m.instrument.Model
}
}
}, JsonRequestBehavior.AllowGet);
}
And here I show (2):
public JsonResult All(int page, int pageSize)
{
var musicians = db.Musicians;
var pageOfMusicians = musicians.Skip((page-1) * pageSize).Take(pageSize);
return Json(new
{
error = false,
message = "",
musiciansCount = musicians.Count(),
page = page,
pageSize = pageSize
musicians = from m in pageOfMusicians select new
{
musicianId = m.MusicianId,
name = m.Name,
instrument = new
{
instrumentId = m.instrument.InstrumentId,
model = m.instrument.Model
}
}
}, JsonRequestBehavior.AllowGet);
}
This has several problems:
If I want to change the JSON format, I have to change it in every single action!
example: If I want to change "name" to "fullname", I have to change it in Members() and All()
Lot of "copy pasting": If I'm creating a new action that somewhere in the structure returns a musician, I need to copy and paste that piece of code that represents the musician
{
musicianId = p.MusicianId,
name = p.Name,
instrument = new
{
instrumentId = instrument.InstrumentId,
model = instrument.Model
}
}
Code is too large
What solution exists to this problem?
If you propose a framework, please show me how would the previous queries look with that framework
Notice I'm always using Linq-to-entities in my examples, and I would like to keep it like that because of performance issues. I know that with Linq-to-objects I could to something like:
from m in pageOfMusicians.ToList() select m.GetDTO()
Being GetDTO() some method that can be run with Linq-to-Objects.
But then, again, I want to stick to Linq-to-Entities

Alternative 1
If you don't worry about using dynamics mixed with regular typed C# code you could make a utility method like...
public static dynamic PrepareForMusiciansView(IQuerable<Musician> musicians)
{
return musicians.Select(m => new
{
musicianId = m.MusicianId,
name = m.Name,
instrument = new
{
instrumentId = m.instrument.InstrumentId,
model = m.instrument.Model
}
}
}
...and then...
return Json(new
{
error = false,
message = "",
musiciansCount = musicians.Count(),
page = page,
pageSize = pageSize
musicians = Util.PrepareForMusiciansView(pageOfMusicians)
}, JsonRequestBehavior.AllowGet);
The method name should clearly reflect its purpose in terms of your application. Maybe you want to focus more on the serialization function and use a name like PrepareForJson. Also, it should be consistent with your coding standards. I would avoid it if nowhere else dynamics is used.
Alternative 2
Use AutoMapper (available via NuGet).
With AutoMapper you'd typically have DTO classes for Musician and Instrument, having the properties you want to expose in the view. If these properties have the same names as those in the source classes, AutoMapper will match them by name convention.
Using AutoMapper always involves defining the mappings and executing mappings. Defining the mappings should be done once at application startup. It looks like...
Mapper.CreateMap<Musician, MusicianDto>();
Mapper.CreateMap<Instrument, InstrumentDto>();
There are different ways to execute the mappings, but when working with IQueryable the preferred way is
musicians = pageOfMusicians.Project().To<MusicianDto>()
This projects IQueryable<Musician> to IQueryable<MusicianDto>, including the nested Instrument (if the DTO has a property of that name).
These are two viable alternatives I can think of to reduce the awkward new {} statements to reusable one-liners. It really depends on your application and coding style which alternative you prefer.

Cannot implicitly convert type '.List<AnonymousType#1>' to '.List<WebApplication2.Customer>'

In the following code that returns a list:
public List<Customer> GeAllCust()
{
var results = db.Customers
.Select(x => new { x.CustName, x.CustEmail, x.CustAddress, x.CustContactNo })
.ToList()
return results;
}
I get an error reporting that C# can't convert the list:
Error: Cannot implicitly convert type System.Collections.Generic.List<AnonymousType#1> to System.Collections.Generic.List<WebApplication2.Customer>
Why is that?
Here's a screenshot showing some additional information that Visual Studio provides in a tooltip for the error:
Is it right way to return some columns instead of whole table....?
public object GeAllCust()
{
var results = db.Customers.Select(x => new { x.CustName, x.CustEmail, x.CustAddress, x.CustContactNo }).ToList();
return results;
}

When you look the code:
x => new { ... }
This creates a new anonymous type. If you don't need to pull back only a particular set of columns, you can just do the following:
return db.Customers.ToList();
This assumes that Customers is an IEnumerable<Customer>, which should match up with what you are trying to return.
Edit
You have noted that you only want to return a certain subset of columns. If you want any sort of compiler help when coding this, you need to make a custom class to hold the values:
public class CustomerMinInfo
{
public string Name { get; set; }
public string Email { get; set; }
public string Address { get; set; }
public int? ContactNumber { get; set; }
}
Then change your function to the following:
public List<CustomerMinInfo> GetAllCust()
{
var results = db.Customers.Select(x => new CustomerMinInfo()
{
Name = x.CustName,
Email = x.Email,
Address = x.Address,
ContactNumber = x.CustContactNo
})
.ToList();
return results;
}
This will work, however, you will lose all relationship to the database context. This means if you update the returned values, it will not stick it back into the database.
Also, just to repeat my comment, returning more columns (with the exception of byte arrays) does not necessarily mean longer execution time. Returning a lot of rows means more execution time. Your function is returning every single customer in the database, which when your system grows, will start to hang your program, even with the reduced amount of columns.

You are selecting to an anonymous type, which is not a Customer.
If you want to do (sort of) this, you can write it like this:
return db.Customers.Select(x => new Customer { Name = x.CustName, Email = x.CustEmail, Address = x.CustAddress, ContactNo = x.ContactNo }).ToList();
This assumes the properties on your Customer object are what I called them.
** EDIT ** Per your comment,
If you want to return a subset of the table, you can do one of two things:
Return the translated form of Customer as I specified above, or:
Create a new class for your business layer that only has only those four fields, and change your method to return a List<ShrunkenCustomer> (assuming ShunkenCustomer is the name that you choose for your new class.)

GetAllCust() is supposed to return a List of Customer, Select New will create a list of Anonymous Types, you need to return a list of Customer from your query.
try:
var results = db.Customers.Select( new Customer{CustName = x.CustName}).ToList(); //include other fields

I guess Customer is a class you have defined yourself?
The my suggestion would be to do something like the following:
var results = db.Customers.Select(x => new Customer(x.Custname, x.CustEmail, x.CustAddress, x.CustContactNo)).ToList();
The reason is that you are trying to return a list of Customer but the results from your link is an anonymous class containing those four values.
This would of course require that you have a constructor that takes those four values.

Basically whatever u got in var type, loop on that and store it in list<> object then loop and achieve ur target.Here I m posting code for Master details.
List obj = new List();
var orderlist = (from a in db.Order_Master
join b in db.UserAccounts on a.User_Id equals b.Id into abc
from b in abc.DefaultIfEmpty()
select new
{
Order_Id = a.Order_Id,
User_Name = b.FirstName,
Order_Date = a.Order_Date,
Tot_Qty = a.Tot_Qty,
Tot_Price = a.Tot_Price,
Order_Status = a.Order_Status,
Payment_Mode = a.Payment_Mode,
Address_Id = a.Address_Id
});
List<MasterOrder> ob = new List<MasterOrder>();
foreach (var item in orderlist)
{
MasterOrder clr = new MasterOrder();
clr.Order_Id = item.Order_Id;
clr.User_Name = item.User_Name;
clr.Order_Date = item.Order_Date;
clr.Tot_Qty = item.Tot_Qty;
clr.Tot_Price = item.Tot_Price;
clr.Order_Status = item.Order_Status;
clr.Payment_Mode = item.Payment_Mode;
clr.Address_Id = item.Address_Id;
ob.Add(clr);
}
using(ecom_storeEntities en=new ecom_storeEntities())
{
var Masterlist = en.Order_Master.OrderByDescending(a => a.Order_Id).ToList();
foreach (var i in ob)
{
var Child = en.Order_Child.Where(a => a.Order_Id==i.Order_Id).ToList();
obj.Add(new OrderMasterChild
{
Master = i,
Childs = Child
});
}
}