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Entity Framework: how to solve table in table

I'm testing the following scenario (code below): create a shopping mall, with shops, with cashiers, with cash desks and persons operating it.
So I've created the following classes
Table Mall
Table Shop
Table CashDesk
Table Person
Basic classes with an ID and a name.
Then I need a derived class from Person being PersonCashier or PersonCustomer.
Since everything is related, I need to create intersection tables for the many to many scenarios.
I've created the following intersection tables:
The Mall contains shops: MallShop
The shop contains CashDesks: MallShopCashDesk
And the CashDesk containing cashiers: MallShopCashDeskPersonCashier
This just doesnt feel right. Can anyone help me out on a best practice
public class Mall
{
public int Id { get; set; }
[Required]
[MaxLength(100)]
public string Name { get; set; }
[Required]
public int NumberOfShopSpaces { get; set; }
}
public class Shop
{
public int Id { get; set; }
[Required]
[MaxLength(100)]
public string Name { get; set; }
}
public class CashDesk
{
public int Id { get; set; }
[Required]
public string Name { get; set; }
}
public class Person
{
public int Id { get; set; }
[Required]
public string FullName { get; set; }
[Required]
public string Gender { get; set; }
}
public class PersonCashier : Person
{
[Required]
public int ShopId { get; set; }
public virtual Shop Shop { get; set; }
}
These are the base classes. How should i add a shop to a mall, a cashdesk to a shop, and a cashier to a cashdesk? (i've tried alot but posting the code would make the question look like spaghetti)

If this is code first then EF will make the relationship tables for you. You just need to add the relationships in your classes.
Exactly what they should be is not clear from your description because it depends on what relationships you want; if you want a many-many between PersonCashier and CashDesk it would be like this:
public class CashDesk
{
public List<PersonCashier> Cashiers { get; set; }
}
public class PersonCashier : Person
{
public List<CashDesk> CashDesks { get; set; }
}
(not showing all the fields for brevity)

public class Mall
{
public int Id { get; set; }
[Required]
[MaxLength(100)]
public string Name { get; set; }
[Required]
public int NumberOfShopSpaces { get; set; }
List<Shop> CurrentShops { get; set; }
}
public class Shop
{
public int Id { get; set; }
[Required]
[MaxLength(100)]
public string Name { get; set; }
public List<CashDesk> CashDesks { get;set; }
}
I added the list of shops to the Mall class and CashDesks to Shops. This gives you a list of shops in the mall, and a list of cashdesks in each shop and you can follow this method for everything else you need.
If you have a database, you will have a Mall table and a Shop table.
The Shop table can have a Foreign Key to the Mall table, that's how you link them and this will work with the class structure at the top.
Or, you can have another table called MallShops where you have 2 fields, one being the MallID, the other the ShopID. This is called a Link table.
Both approaches will work with the second allowing a more complex structure with lots of Malls linked to Lots of Shops.
I would start with the database structure first, make sure you cover all you need, then you can do the classes etc in a way that makes sense. If you use something like EntityFramework then it will create all the classes for you once your database structure is ready.

How to auto save complex model with lists of models in it?

I am creating a quiz creator module. There are 5 subjects. Each subject has 2000 questions.
Say, it's called "Create Full model test", and it will contain 100 questions, 20 questions from 5 subjects. So, 20*5=100
In the UI, creator will first select "Create full model test" from the drop down. Suppose if he select the "Full model test". He will have to select one subject among 5 subjects, then he will have to select 20 questions per subject. and then will have to save them into that "Full model test" segment.
If he selects English, he will have to select 20 questions, then he will have to select another subject, for example, physics, and will have to select another 20 questions for physics, then he will have to select maths and then will have to select another 20 questions and so on for maths. Finally 100 questions will be submitted by the form.
Now, my question is, how can I auto save the selected questions into that "Full model test" segment, so that he can continue saving 5 subject's questions before he submit the form.
Here is my Department model:
namespace MvcBCS.Models
{
public class Department
{
[Key]
public int DepartmentId { get; set; }
public string DepartmentName { get; set; }
public string DepartmentCode { get; set; }
public virtual ICollection<Subject> Subject { get; set; }
public virtual ICollection<Section> Section { get; set; }
public virtual ICollection<Subsection> Subsection { get; set; }
}
}
Here is my Subject Model:
namespace MvcBCS.Models
{
public class Subject
{
[Key]
public int SubjectId { get; set; }
public string SubjectName { get; set; }
public string SubjectCode { get; set; }
public int DepartmentId { get; set; }
public virtual Department Department { get; set; }
public virtual ICollection<Section> Section { get; set; }
}
}
Here is the Section Model:
namespace MvcBCS.Models
{
public class Section
{
[ForeignKey("Department")]
public int? DepartmentId { get; set; }
public virtual Department Department { get; set; }
[ForeignKey("Subject")]
public int? SubjectId { get; set; }
public virtual Subject Subject { get; set; }
[Key]
public int SectionId { get; set; }
public string SectionName { get; set; }
}
}
Here is the subjection model:
namespace MvcBCS.Models
{
public class Subsection
{
[ForeignKey("Department")]
public int? DepartmentId { get; set; }
public virtual Department Department { get; set; }
[ForeignKey("Subject")]
public int? SubjectId { get; set; }
public virtual Subject Subject { get; set; }
[ForeignKey("Section")]
public int? SectionId { get; set; }
public virtual Section Section { get; set; }
[Key]
public int SubsectionId { get; set; }
public string SubsectionName { get; set; }
public string SubsectionCode { get; set; }
}
}

All that you need is just to store all temporary data on client side.
And when you get complete pasts or even full set of data - send it to server using POST/JSON/XML/etc.
I think it such case it will be better for you to use some kind of JavaScript frameworks, for example KnockoutJS, which with only few click's and couple lines of code will allows you to store all your data on client side in object-based model.
Anyway if you will use any framework or not, you should use JavaScript to store all of your data, including question, answers and subjects. JavaScript will allows you to store,validate and send all data that you need.
To make your work with JavaScript easier and faster - you can use jQuery library which contains functions for interaction with both DOM structure and server side.
To make learning of KnockoutJS easier just use tutorial: http://learn.knockoutjs.com

This is how I am going to attempt it.
business rules:
- full model test will be completed if all the subjects questions are submitted by certain user.
Assumption: we knew in advance that we have five subjects. Therefore
public enum Subject
{
English,
Physics,
...
}
Test Poco entity structure:
public class Test
{
public int Id{get;set;}
public User CreatedBy{get;set;}
public Subject Subject{get;set;}
public bool IsFullTestCompleted{get;set;}
public string Question1{get;set;}
public string Question2{get;set;}
...
}
Assumptions:
You can use partial views/ajax/Jquery/Angularjs/Knockout whatever suits you best in your problem context to implement it to auto save the changes
You will add necessary view model with appropriate validation annotations/attributes
you will add validation where necessary.
you will add/update the Test entity. like for first subject you will add data into Test entity, and subsequently you will update it.
Hope it will be helpful

How to get data from additional tables using EF/LINQ

I have following three tables
Employee(empid, name)
Role(roleid, name)
EmpRoleMap(mapid, empid,roleid)
In the index view I show the link of employees with edit link with each employee. When user clicks on edit it opens the edit screeen for the selected employee.
For this page to render I am making two calls to database. First is to get the details about selected employee. Seconds is to query the EmpRoleMap table to find out what all roles that employee belongs to.
I want to do the same stuff in single database call, i.e single call would give me the details about the employee and the roleID from EmpRoleMap & RoleName list for the given Employee.
I am using Code First approach with Scaffolding.
How can I do this using EntityFramework? Can we use "Include" clause with LINQ to get the additional data from other tables (here EmpRoleMap,Role).

You have to do a good Entity Model design. I'm going to try to show you an example of what I'm saying, but remember that at this moment I cannot check the code.
public class EmployeeModel
{
[Key]
[ForeignKey("EmployeeRoles")]
public decimal empid { get; set; }
public string name { get; set; }
public virtual List<EmpRoleModel> EmployeeRoles { get; set; }
}
public class RoleModel
{
[Key]
public decimal roleid { get; set; }
public string name { get; set; }
}
public class EmpRoleModel
{
[Key]
[Column(Order = 0)]
[ForeignKey("Employee")]
public decimal empid { get; set; }
[Key]
[Column(Order = 1)]
[ForeignKey("Role")]
public decimal roleid { get; set; }
public virtual EmployeeModel Employee { get; set; }
public virtual RoleModel Role { get; set; }
}
Now you can navigate to employee roles by the EmployeeRoles property.
Please try this code and give me feedback.

Using ICollection with MVC & Entity framework

Hi I'm learning to use MVc using Code first method. I'm having trouble understanding the use of ICollection<> with my setup. I have two classes/entitys: 'Restaurant' & 'RestaurantReview' as below:
public class Restaurant
{
public int Id { get; set; }
public string Name { get; set; }
public string City { get; set; }
public string Country { get; set; }
public ICollection<RestaurantReview> Reviews { get; set; }
}
and.....
public class RestaurantReview
{
public int Id { get; set; }
public int Rating { get; set; }
public string Body { get; set; }
public string ReviewerName { get; set; }
public int RestaurantId { get; set; }
}
now whats confusing me is the last property of the Restaurant class. Why is it of type 'ICollection' and uses my RestaurantReview class as a parameter, what does it do, hope I
have made myself clear

It's a definition of one to many relationship.
With that property (sometimes called Navigation Property) Entity Framework will be able to connect Review with Restaurant it was written about. It will also allow you to get Review entities for given Restaurant entity really easily.
You can also remove public int RestaurantId { get; set; } from RestaurantReview class - That column is gonna be generated automatically by EF because of ICollection<RestaurantReview> in Restaurant class.

Data modeling for Country,Region,City

Im want to create a data structure for using within my MVC3 application. The site holds videos uploaded by users, I want to be able of setting up a location for the video so later on you can search based on the country, region or city.
The modeling of those entities is not a big problem to me, my question is which class attribute should I use for my video entity.
public class Country
{
int CountryId
string CountryName
}
public class Region
{
int RegionId
string RegionName
int FK_CountryId
}
public class City
{
int CityId
string CityName
int FK_CountryId
int FK_RegionId
}
........
public class Video
{
int VideoId;
string VideoName;
**Location VideoLocation;**
}
**public class Location
{
int LocationId;
Country CountrId;
Region RegionId;
City CityId;
}**
My initial idea, but I think it is not a really good design since you can have 2 identical rows for a Location, where it should be ideal to keep a unique reference to Locations
What do you think in terms of good design and performance?

That is everyone's nightmare I guess. Well...at least that was my nightmare when designing one of the applications.
Depending on your secenario you might keep countries, cities, regions as different entities. Everything is find with that approach until you want the user to select either country, region or city. Looks like you would need to have nullable fields, which is not really the best practice, because you would then have to fully rely on application logic to maintain data integrity.
Example of that approach would be:
public class Country
{
public string Code { get; set; } //country ID would not make sense in this approach
public string Name { get; set; }
}
public class Region
{
public string Code { get; set; }
public string Name { get; set; }
public string CountryCode { get; set; } //1 region is assigned to only 1 country
}
public class City
{
public string Code { get; set; }
public string Name { get; set; }
public string RegionCode { get; set; } //1 city is assigned to only 1 region
}
It looks good, simple to understand but think about the table where you capture what's been selected. If you only care about city (last item in dependency list), it's all clear and fine.
public class UserSelectionWithCityOnly
{
public string CityCode { get; set; }
}
Pretty easy and straight forward? Looks like it is.
Consider the scenario where you can select either country,city or region....it get's really messy:
public class UserSelectionWithEitherSelected
{
public string? CityCode { get; set; }
public string? RegionCode { get; set; }
public string? CountryCode { get; set; }
}
well...you could always check if CityCode.HasValue, but from DB point of view that would be a nullable field, which can add dirty data (should be fine if you are not pedantic about having neat and clean DB)
So they way I solve this was by creating one hierarchical table with parent item id :
public class MySolutionForDestinations
{
public int DestinationId { get; set; } //primary key
public int ParentDestinationId { get; set; }
public string Code { get; set; }
public string Name { get; set; }
public DestinationLevel Level { get; set; }
}
public enum DestinationLevel
{
Country = 0,
Region = 1,
City = 2
}
it's probably not the most elegant solution, but it works really well. In this approach you only care about DestinationId which can be a country Id, region Id or a city Id, so you would definitely avoid having dirty data and can implement 1 to 1 mapping.
Hope this will be usefull