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How can I get a list of objects related to a min from a Linq

I have a Linq Query that is working as intended, but I need to add the code so that it will show me ONLY the people with the less cases assigned for an app that is been used to treat customers inquiries. The idea behind the query is so that it will let me automatically assign inquiries randomly between those agents which have less assigned issues to cover.
As a simple example, lets say I have 5 agents with just 1 case each, I need to randomly assign one of them to an Inquire which has currently no agent assigned. So all I'm looking for is a way to actually get all the agents with the smallest number of cases assigned.
So far this is the full proof of concept code:
var inquires = new List<Inquire>();
var agents = new List<Agent>();
LoadData();
var assignationsPerAgent = (from agent in agents
join inq in inquires on agent equals inq.AssignedAgent into agentsInInquires
select new {
o_agent = agent,
casesAssignedTo = agentsInInquires.Count()
}).ToList();
//This works but is NOT the kind of solution I'm looking for
var min = assignationsPerAgent.Min(c => c.casesAsignedTo);
var agentWithMin = assignationsPerAgent.Where(a => a.casesAsignedTo == min);
Console.WriteLine();
void LoadData()
{
agents = new(){
new Agent{ Id = Guid.Parse("317d3d26-25c2-49da-aa4b-b7e49a1b9015"), Name = "Robert" },
new Agent{ Id = Guid.Parse("84188e21-8147-498f-bc2a-59874dc4a24a"), Name = "Corina" },
new Agent{ Id = Guid.Parse("90ca6658-95d4-4df4-a072-159087feddc0"), Name = "John" },
new Agent{ Id = Guid.Parse("34e091e4-cc7a-4222-9885-5de5bb5a0291"), Name = "Jack"},
new Agent{ Id = Guid.Parse("f22dcb4e-e927-4ddf-ae66-f37c0de6753d"), Name = "Samuel"}
};
inquires = new(){
new Inquire{ CustomerName = "Paula", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("317d3d26-25c2-49da-aa4b-b7e49a1b9015"))},
new Inquire{ CustomerName = "Barry", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("84188e21-8147-498f-bc2a-59874dc4a24a"))},
new Inquire{ CustomerName = "Bertie", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("84188e21-8147-498f-bc2a-59874dc4a24a"))},
new Inquire{ CustomerName = "Herman", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("90ca6658-95d4-4df4-a072-159087feddc0"))},
new Inquire{ CustomerName = "Ashley", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("317d3d26-25c2-49da-aa4b-b7e49a1b9015"))},
new Inquire{ CustomerName = "Tate", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("90ca6658-95d4-4df4-a072-159087feddc0"))},
new Inquire{ CustomerName = "Bonnie", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("90ca6658-95d4-4df4-a072-159087feddc0"))},
new Inquire{ CustomerName = "Tabitha", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("90ca6658-95d4-4df4-a072-159087feddc0"))},
new Inquire{ CustomerName = "Ashley", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("34e091e4-cc7a-4222-9885-5de5bb5a0291"))},
new Inquire{ CustomerName = "Josie", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("84188e21-8147-498f-bc2a-59874dc4a24a"))},
new Inquire{ CustomerName = "Kelly", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("84188e21-8147-498f-bc2a-59874dc4a24a"))},
new Inquire{ CustomerName = "Kelly", AsignedAgent = agents.Single(a => a.Id == Guid.Parse("f22dcb4e-e927-4ddf-ae66-f37c0de6753d"))},
};
}
#nullable disable
class Inquire
{
private Guid _id;
public Guid Id
{
get
{
return _id;
}
private set
{
_id = Guid.NewGuid();
}
}
public string CustomerName { get; set; }
public Agent AsignedAgent { get; set; }
}
#nullable disable
class Agent
{
public Guid Id {get; set;}
public string Name { get; set; }
}
Please take in consideration that the assignationsPerAgent variable is simulating data coming from a query in the database (The actual query is below). If the "easy" way to do this comes from the SQL that it's also an acceptable solution.
SELECT u.Id, COUNT(g.Id) as QtyAsig
FROM Users as u
LEFT JOIN GeneralInquires AS g ON u.Id = g.UserId
GROUP BY u.Id
ORDER BY COUNT(g.Id)
What I'm getting from this Query is:
Id QtyAsig
8A21A6D2-0CEC-4F5C-2A6B-08DA60967E94 1
323C8D1A-2FAE-4ECC-D7A2-08DA6098F19A 1
BA485F3C-C44A-4FE5-9BFA-08DA64EF283A 1
8F0E856E-FA0B-4167-BBEF-08DA6451FA81 2
40952727-5C76-4902-9C4F-08DA638B3068 3
DD51085A-5BE3-4872-F4B5-08DA6E7828AA 4
What I need is:
Id QtyAsig
8A21A6D2-0CEC-4F5C-2A6B-08DA60967E94 1
323C8D1A-2FAE-4ECC-D7A2-08DA6098F19A 1
BA485F3C-C44A-4FE5-9BFA-08DA64EF283A 1
Thank you in advance!

check this
var assignationsPerAgent = (from agent in agents
join inq in inquires on agent equals inq.AsignedAgent into agentsInInquires
from inq in agentsInInquires.DefaultIfEmpty()
select new
{
o_agent = agent,
casesAssignedTo = agentsInInquires.Count()
}).GroupBy(x=>x.casesAssignedTo).OrderBy(x=>x.Key).FirstOrDefault();

Linq doesn't require one statement and splitting results has no impact on performance. Try following :
List<Inquire> sortedInquires = inquires.OrderBy(x => x.AsignedAgent.Id).ToList();
var results = (from a in agents
//join i in sortedInquires on a.Id equals i.Id
join i in sortedInquires on a.Id equals i.AssignedAgent
select new { agent = a, inquires = i}
).GroupBy(x => x.agent.Id)
.Select(x => x.First())
.ToList();

Dapper One To Many Relationship

I have 3 tables structured in the following way:
CREATE TABLE [User](
Id int NOT NULL,
Name varchar(50)
PRIMARY KEY (Id)
)
CREATE TABLE [Role](
Id int NOT NULL,
UserId int NOT NULL,
Name varchar(50),
PRIMARY KEY (Id),
FOREIGN KEY (UserId) REFERENCES [User](Id)
)
CREATE TABLE [Description](
Id int NOT NULL,
RoleId int NOT NULL,
Name varchar(50)
FOREIGN KEY (RoleId) REFERENCES [Role](Id)
)
As you can see it is one to many relationship nested twice. In the code I have the following classes to represent them:
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public IEnumerable<Role> Roles { get; set; }
}
public class Role
{
public int Id { get; set; }
public int UserId { get; set; }
public string Name { get; set; }
public IEnumerable<Description> Descriptions { get; set; }
}
public class Description
{
public int Id { get; set; }
public int RoleId { get; set; }
public string Name { get; set; }
}
Now I need to query for the user and also get all fields that come with it. I have figured out a way to do that using QueryMultiple such as this:
var queryOne = "SELECT Id, Name FROM [User] WHERE Id = 1";
var queryTwo = "SELECT r.Id, r.UserId, r.Name FROM [User] u INNER JOIN [Role] r ON u.Id = r.UserId WHERE u.Id = 1";
var queryThree = "SELECT d.Id, d.RoleId, d.Name FROM [User] u INNER JOIN [Role] r ON u.Id = r.UserId INNER JOIN [Description] d ON r.Id = d.RoleId WHERE u.Id = 1";
var conn = new SqlConnection();
using (var con = conn)
{
var result = con.QueryMultiple(queryOne + " " + queryTwo + " " + queryThree);
var users = result.Read<User>().FirstOrDefault();
var roles = result.Read<Role>();
var descriptions = result.Read<Description>();
if (users != null && roles != null)
{
users.Roles = roles;
Console.WriteLine("User: " + users.Name);
foreach (var role in users.Roles)
{
Console.WriteLine("Role: " + role.Name);
if (descriptions != null)
{
role.Descriptions = descriptions.Where(d => d.RoleId == role.Id);
foreach (var roleDescription in role.Descriptions)
{
Console.WriteLine("Description: " + roleDescription.Name);
}
}
}
}
}
The result is:
User: Bob
Role: Tester
Description: Tester First Description
Description: Tester Second Description
Description: Tester Third Description
Role: Manager
Description: Manager First Description
Description: Manager Second Description
Description: Manager Third Description
Role: Programmer
Description: Programmer First Description
Description: Programmer Second Description
Description: Programmer Third Description
Main Question:
While the above code works it feels too messy. I was wondering if there is a better/easier way to achieve this?
Bonus Points:
Please also feel free to suggest a better way to query this than using inner joins. My goal is to improve performance.
EDIT:
I came up with option two as well, but again I don't think its a good solution. With option 2 I create a 4th object that will contain results of the 3 objects combined such as this:
public class Combination
{
public int UserId { get; set; }
public string UserName { get; set; }
public int RoleId { get; set; }
public string RoleName { get; set; }
public int DescriptionId { get; set; }
public string DescriptionName { get; set; }
}
Then I process it like this:
var queryFour = "SELECT u.Id as 'UserId', u.Name as 'UserName', r.Id as 'RoleId', r.Name as 'RoleName', d.Id as 'DescriptionId', d.Name as 'DescriptionName' FROM [User] u INNER JOIN [Role] r ON u.Id = r.UserId INNER JOIN [Description] d ON r.Id = d.RoleId WHERE u.Id = 1";
var conn = new SqlConnection();
using (var con = conn)
{
var myUser = new User();
var result = con.Query<Combination>(queryFour);
if (result != null)
{
var user = result.FirstOrDefault();
myUser.Id = user.UserId;
myUser.Name = user.UserName;
var roles = result.GroupBy(x => x.RoleId).Select(x => x.FirstOrDefault());
var myRoles = new List<Role>();
if (roles != null)
{
foreach (var role in roles)
{
var myRole = new Role
{
Id = role.RoleId,
Name = role.RoleName
};
var descriptions = result.Where(x => x.RoleId == myRole.Id);
var descList = new List<Description>();
foreach (var description in descriptions)
{
var desc = new Description
{
Id = description.DescriptionId,
RoleId = description.RoleId,
Name = description.DescriptionName
};
descList.Add(desc);
}
myRole.Descriptions = descList;
myRoles.Add(myRole);
}
}
myUser.Roles = myRoles;
}
Console.WriteLine("User: " + myUser.Name);
foreach (var myUserRole in myUser.Roles)
{
Console.WriteLine("Role: " + myUserRole.Name);
foreach (var description in myUserRole.Descriptions)
{
Console.WriteLine("Description: " + description.Name);
}
}
}
The resulting output is the same in both methods and the second method uses 1 query as opposed to 3.
EDIT 2: Something to consider, my data for these 3 tables are updated often.
EDIT 3:
private static void SqlTest()
{
using (IDbConnection connection = new SqlConnection())
{
var queryOne = "SELECT Id FROM [TestTable] With(nolock) WHERE Id = 1";
var queryTwo = "SELECT B.Id, B.TestTableId FROM [TestTable] A With(nolock) INNER JOIN [TestTable2] B With(nolock) ON A.Id = B.TestTableId WHERE A.Id = 1";
var queryThree = "SELECT C.Id, C.TestTable2Id FROM [TestTable3] C With(nolock) INNER JOIN [TestTable2] B With(nolock) ON B.Id = C.TestTable2Id INNER JOIN [TestTable] A With(nolock) ON A.Id = B.TestTableId WHERE A.Id = 1";
var gridReader = connection.QueryMultiple(queryOne + " " + queryTwo + " " + queryThree);
var user = gridReader.Read<Class1>().FirstOrDefault();
var roles = gridReader.Read<Class2>().ToList();
var descriptions = gridReader.Read<Class3>().ToLookup(d => d.Id);
user.Roles= roles;
user.Roles.ForEach(r => r.Properties = descriptions[r.Id].ToList());
}
}

Your first option can be simplified to the following. It removes the deep control structure nesting. You can generalize it to deeper nesting without adding more nesting/complexity.
var queryOne = "SELECT Id, Name FROM [User] WHERE Id = 1";
var queryTwo = "SELECT r.Id, r.UserId, r.Name FROM [User] u INNER JOIN [Role] r ON u.Id = r.UserId WHERE u.Id = 1";
var queryThree = "SELECT d.Id, d.RoleId, d.Name FROM [User] u INNER JOIN [Role] r ON u.Id = r.UserId INNER JOIN [Description] d ON r.Id = d.RoleId WHERE u.Id = 1";
var conn = new SqlConnection();
using (var con = conn)
{
var gridReader = con.QueryMultiple(queryOne + " " + queryTwo + " " + queryThree);
var user = gridReader.Read<User>().FirstOrDefault();
if (user == null)
{
return;
}
var roles = gridReader.Read<Role>().ToList();
var descriptions = gridReader.Read<Description>().ToLookup(d => d.RoleId);
user.Roles = roles;
roles.ForEach(r => r.Descriptions = descriptions[r.Id]);
}
Performance-wise it behaves the same as your first option.
I would't go with your second option (or the similar view based one): in case you have R roles, and on average D descriptions per roles, you would query 6*R*D cells instead of 2+3*R+3*D. If R and D are high, you'd be querying a lot more data, and the cost of deserialization will be to high compared to running 3 queries instead of 1.

An alternative approach (Working code snippet with .Net Core):
Why not create a database View like this -
create view myview
As
SELECT u.Id as 'UserId', u.Name as 'UserName', r.Id as 'RoleId',
r.Name as 'RoleName', d.Id as 'DescriptionId', d.Name as 'DescriptionName'
FROM User u INNER JOIN Role r ON u.Id = r.UserId
INNER JOIN Description d ON r.Id = d.RoleId;
Then you can use your cleaner query as below :
public List<Combination> GetData(int userId)
{
String query = "select * from myview" + " where userId = " + userId + ";";
using (System.Data.Common.DbConnection _Connection = database.Connection)
{
_Connection.Open();
return _Connection.Query<Combination>(query).ToList();
}
}
And your processing code will look like this :
[Note: This can be enhanced even further.]
public static void process (List<Combination> list)
{
User myUser = new User(); myUser.Id = list[0].UserId; myUser.Name = list[0].UserName;
var myroles = new List<Role>(); var r = new Role(); string currentRole = list[0].RoleName;
var descList = new List<Description>(); var d = new Description();
// All stuff done in a single loop.
foreach (var v in list)
{
d = new Description() { Id = v.DescriptionId, RoleId = v.RoleId, Name = v.DescriptionName };
if (currentRole == v.RoleName)
{
r = new Role() { Id = v.RoleId, Name = v.RoleName, UserId = v.UserId, Descriptions = descList };
descList.Add(d);
}
else
{
myroles.Add(r);
descList = new List<Description>(); descList.Add(d);
currentRole = v.RoleName;
}
}
myroles.Add(r);
myUser.Roles = myroles;
Console.WriteLine("User: " + myUser.Name);
foreach (var myUserRole in myUser.Roles)
{
Console.WriteLine("Role: " + myUserRole.Name);
foreach (var description in myUserRole.Descriptions)
{
Console.WriteLine("Description: " + description.Name);
}
}
}
From the performance standpoint, Inner Joins are better than other forms of query like subquery, Co-related subquery, etc. But ultimately everything boils down to the SQL execution plan.

The tl;dr of my answer to you:
Abstract. You should break-up things into the different jobs they do. C# gives you functions and classes, they can help clean up code a lot.
If you can look at a chunk of code and say "this chunk is basically taking something and doing blah with it to get some result..", then make a function called SomeResult DoBlah(SomeThing thing)
Don't let a little more code scare you, it may make the big picture seem more complex at first glance. But it will make small chunks of code way easier to understand, and that makes the big picture easier to understand.
My full answer:
There are a couple of things you could do that would make this cleaner. Probably the biggest thing you could do for yourself, is to separate out some of the responsibilities/concerns. You have a lot of different things going on, and all of it is in one place, relying on everything staying exactly like it is, forever. If you change something, you will have to change things all over the place to make sure everything works. This is called "coupling", and coupling is bad... um-kay.
At the broadest level, you have three different things going on: 1. You are trying to apply logic to users and roles (i.e. You want to get info on all of the users in a role.) 2. You are trying to pull info from a database, and fit it into User, Role, and Description objects. 3. You are trying to display information about Users, Roles, and Descriptions.
So if I were you, I would have at least 3 classes right there. \
Program that is the driver of your application. It should have a main function and should use the other 3 classes.
DisplayManager that can be responsible for writing info out to a console. It should be constructed with an IEnumerable<User> and should have a public method public void DisplayInfo() that will write its list of users to a console.
UserDataAccess that can be used for fetching a list of users from a database. I would have it expose a public method for public IEnumerable<User> GetUsersByRoleID(int roleID)
This way, your main program would look something like this:
public static void Main(String[] args)
{
int roleID = 6;
UserDataAccess dataAccess = new UserDataAccess();
IEnumerable<User> usersInRole = dataAccess.GetUsersByRoleID(roleID);
DisplayManager displayManager = new DisplayManager(usersInRole);
displayManager.DisplayInfo();
}
Honestly, this is a simplified version of what I would do if the problem had more functionality then just getting a single specific piece of info. You should look into SOLID principles. Specifically "Single Responsibility" and "Dependency Inversion", these principles can really clean up some "messy"/"smelly" code.
Next, as far as your actually data access goes, since you are using dapper, you should be able to map nested objects using build in dapper functionality. I believe this link should be of some help to you in this aspect.

LINQ Filtering Select Ouput with IEnumerable<T>

I have following methods:
Controller:
...
var appmap = Services.GetReqAppMapList(value);
var applist = Services.GetApplicationList(docid, appid, reqid, appmap);
...
Model:
public static IEnumerable<AppMap> GetReqAppMapList(int aiRequestTypeId)
{
try
{
var appmap = new List<AppMap>();
using (var eties = new eRequestsEntities())
{
appmap = (from ram in eties.ReqAppMaps
where ram.IsActive == 1
select new AppMap
{
RequestTypeId = ram.RequestTypeId
}).ToList();
return appmap;
}
}
catch(Exception e)
{
throw e;
}
}
public static IEnumerable<TicketApplication> GetApplicationList(int aiDocumentTypeId, int aiApplicationTypeId, int aiRequestTypeId, IEnumerable<AppMap> appmap)
{
try
{
var applicationlist = new List<TicketApplication>();
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
where 1==1
<<<Some Conditions Here???>>>
== && appmap.Contains(app.ApplicationTypeId) ==
&& app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId = app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
return applicationlist;
}
And I was thinking how can filter query result of GetApplicationList using the result from GetReqAppMapList
I'm kinda stuck with the fact that I must convert/cast something to the correct type because every time I do a result.Contains (appmap.Contains to be exact), I always get the following error
Error 4 Instance argument: cannot convert from
'System.Collections.Generic.IEnumerable<Test.Models.AppMap>' to
'System.Linq.ParallelQuery<int?>'

You should directly join the two tables in one query.
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
join ram in applicationentity.ReqAppMaps on app.ApplicationTypeId equals ram.RequestTypeId
where ram.IsActive == 1 && app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId = app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
You can delete the other method if it is not needed anymore. No point hanging onto code which is dead.

Looks like there is no other way to do this (as far as I know), so I have to refactor the code, I hope still that there would be a straight forward conversion and matching method in the future (too lazy). Anyway, please see below for my solution. Hope this helps someone with the same problem in the future. I'm not sure about the performance, but this should work for now.
Controller:
...
var appmap = Services.GetReqAppMapList(value);
var applist = Services.GetApplicationList(docid, appid, reqid, appmap);
...
Model:
<Removed GetReqAppMapList>--bad idea
public static IEnumerable<TicketApplication> GetApplicationList(int aiDocumentTypeId, int aiApplicationTypeId, int aiRequestTypeId)
{
try
{
//This is the magic potion...
List<int?> appmap = new List<int?>();
var applist = (from ram in applicationentity.ReqAppMaps
where ram.RequestTypeId == aiRequestTypeId
&& ram.IsActive == 1
select new AppMap
{
ApplicationTypeId = ram.ApplicationTypeId
}).ToList();
foreach (var item in applist)
{
appmap.Add(item.ApplicationTypeId);
}
//magic potion end
var applicationlist = new List<TicketApplication>();
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
where 1==1
===>>>&& appmap.Contains(app.ApplicationTypeId)<<<===
&& app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId =app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
return applicationlist;
}
A side-note, C# is a strongly-typed language, just make sure your data types matches during evaluation, as int? vs int etc.., will never compile. A small dose of LINQ is enough to send some newbies circling around for hours. One of my ID-10T programming experience but just enough to remind me that my feet's still flat on the ground.

Listing in WCF Entity

I have a problem with LINQ query (see comment) there is a First method and it only shows me the first element.
When I write in the console "Sales Representative" it shows me only the first element of it as in
I would like to get all of data about Sales Representative. How can I do it?
public PracownikDane GetPracownik(string imie)
{
PracownikDane pracownikDane = null;
using (NORTHWNDEntities database = new NORTHWNDEntities())
{
//Employee matchingProduct = database.Employees.First(p => p.Title == imie);
var query = from pros in database.Employees
where pros.Title == imie
select pros;
// Here
Employee pp = query.First();
pracownikDane = new PracownikDane();
pracownikDane.Tytul = pp.Title;
pracownikDane.Imie = pp.FirstName;
pracownikDane.Nazwisko = pp.LastName;
pracownikDane.Kraj = pp.Country;
pracownikDane.Miasto = pp.City;
pracownikDane.Adres = pp.Address;
pracownikDane.Telefon = pp.HomePhone;
pracownikDane.WWW = pp.PhotoPath;
}
return pracownikDane;
}

Right now you are just getting the .First() result from the Query collection:
Employee pp = query.First();
If you want to list all employees you need to iterate through the entire collection.
Now, if you want to return all the employee's you should then store each new "pracownikDane" you create in some sort of IEnumerable
public IEnumerable<PracownikDane> GetPracownik(string imie) {
using (NORTHWNDEntities database = new NORTHWNDEntities())
{
var query = from pros in database.Employees
where pros.Title == imie
select pros;
var EmployeeList = new IEnumerable<PracownikDane>();
foreach(var pp in query)
{
EmployeeList.Add(new PracownikDane()
{
Tytul = pp.Title,
Imie = pp.FirstName,
Nazwisko = pp.LastName,
Kraj = pp.Country,
Miasto = pp.City,
Adres = pp.Address,
Telefon = pp.HomePhone,
WWW = pp.PhotoPath
});
}
return EmployeeList;
}
Then, with this returned List you can then do what ever you wanted with them.

Getting specific columns from an INCLUDE statement with EF

I want to get only specific columns from a query in EF when using an INCLUDE statement instead of bringing back all the columns.
In addition, what if I also wanted to bring back a shorter result set from my Customers object as well.
Is there a way to do this?
Here is my query:
void Main()
{
IEnumerable<Customer> customerProjectsList = GetCustomerProjects();
customerProjectsList.Dump();
}
public List<Customer> GetCustomerProjects()
{
try
{
using (YeagerTech DbContext = new YeagerTech())
{
var customer = DbContext.Customers.Include("Projects");
return customer;
}
}
catch (Exception ex)
{
throw ex;
}
}
EDIT
I've been trying to use the following query, but get an error of "Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.ICollection'. An explicit conversion exists (are you missing a cast?)"
Here is the query:
void Main()
{
List customerProjectsList = GetCustomerProjects();
customerProjectsList.Dump();
}
public List<CustomerDTO> GetCustomerProjects()
{
try
{
using (YeagerTech DbContext = new YeagerTech())
{
var customerlist = DbContext.Customers.Select(s =>
new CustomerDTO()
{
CustomerID = s.CustomerID,
Projects =
from p in Projects
where p.CustomerID == s.CustomerID && p.Quote != null
select new Project { Description = p.Description, Quote = p.Quote }
}).ToList<Project>();
return customerlist.ToList();
}
}
catch (Exception ex)
{
throw ex;
}
}
If I run this same query in LINQPad as a C# statement instead of a C# program, the query results get produced fine.
I am just going bonkers over this simple way to try and get a hierarchal list back with specific columns.
var result = (from c in Customers
select new
{
c.CustomerID,
Projects =
from p in Projects
where p.CustomerID == c.CustomerID && p.Quote != null
select new { p.Description, p.Quote }
});
result.Dump();

You don't necessarily need include; if you have navigation properties between Customers and Projects you can project to new objects:
var customers = (from c in DbContext.Customers
select new
{
FirstName = c.FirstName,
ProjectName = c.Project.Name
}).ToList().Select(x => new Customer
{
FirstName = x.FirstName,
Project = new Project()
{
Name = x.ProjectName
}
}).ToList();
This will return a list of Customers where only the first name is populated and each customer will contain a Project property with the name populated. This is great for performance as the query sent by EF to your database will be short and will return a result set quickly.
Edit:
Taking into account that Projects is an ICollection, I think the most maintenable thing to do would be to create a couple of DTOs:
public CustomerDTO
{
public int CustomerId;
public List<ProjectDTO> projects;
}
public ProjectDTO
{
public string Description;
public string Quote;
}
and project to them like so:
var qry = (from c in context.Customers
select new CustomerDTO()
{
CustomerId = c.CustomerId,
Projects = (from pr in context.Projects
where c.ProjectId equals pr.Id
select new ProjectDTO
{
Description = pr.Description,
Quote = pr.Quote
}).ToList()
});

You have to use projection to limit the columns that are retrieved. Lots of examples of projection can be found on the internet a short example is like this :
DateTime twoDaysAgo = DateTime.Now.AddDays(-2);
var groupSummaries = _recipeContext.Groups.OrderBy(g => g.Name)
.Select(g => new GroupSummaryModel{
Id = g.Id,
Name = g.Name,
Description = g.Description,
NumberOfUsers = g.Users.Count(),
NumberOfNewRecipes = g.Recipes.Count(r => r.PostedOn > twoDaysAgo)
});
I took it from here :
http://www.davepaquette.com/archive/2013/02/09/writing-efficient-queries-with-entity-framework-code-first-part-2.aspx
The point is to use the new mechanism if needed multiple times. Here it is used with new GroupSummaryModel.
EDIT
var qry = (from c in context.Customers
select new CustomerDTO()
{
CustomerId = c.CustomerId,
Projects = (from pr in context.Projects
where c.ProjectId equals pr.Id
select new ProjectDTO
{
Description = pr.Description,
Quote = pr.Quote
}) //--> no tolist here
}).ToList(); //--> only here