I am using Webapi and i have two tables in database and Department and Info tables. Department table has relation with Info table. I am using entity framework to retrieve data from database but I am getting data from only one table INFO so the department table shows NULL it has to show department data because both have relation.
Without Webapi the code is working fine. So where I am wrong and why does not Department table show in webapi.
I hope you understand my question thanks.
Contorller
public class WebApiController : ApiController
{
[HttpGet]
public IHttpActionResult EmployeeList()
{
var List = DB.Infoes.ToList().OrderByDescending(x => x.ID);
return Json(List);
}
}
Model
public partial class Info
{
public int ID { get; set; }
public string Image_Name { get; set; }
public string First_Name { get; set; }
public string Last_name { get; set; }
public string Desription { get; set; }
public Nullable<int> DeprtmentIDFK { get; set; }
public virtual Department Department { get; set; }
}
public partial class Department
{
public int DepartmentID { get; set; }
public string DepartmentName { get; set; }
public virtual ICollection<Info> Infoes { get; set; }
}
As it is discussed here, in order to fetch navigation properties you have to Include them in your IQueryable, otherwise you always get null values.
Related
Can someone guide me on how to construct the proper property navigation on the below tables?
I have these tables in my database:
I then need to relate the Status table to get the status Name on every table
These are my model classes:
[Table("Companies")]
public class CompanyEntity
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int Status_Id { get; set; }
public DateTime Created_Date { get; set; }
public DateTime Updated_Date { get; set; }
[ForeignKey("Status_Id")]
public Status Status { get; set; }
}
[Table("Customers")]
public class CustomerEntity
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int Status_Id { get; set; }
}
[Table("Status")]
public class Status
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public Company Company { get; set; }
}
My goal is to when I get all the Companies or Customers using DBContext e.g. var companies = _dbContext.Companies.ToList(). I want to get the status of every record for Companies and Customers. I'm not so sure how to construct the navigation property properly for the said models.
TIA!
Update #1
After following the below suggestion, yes the Status is not NULL anymore. But, it gets the wrong status id. Instead of using the Status_Id, it uses the Id of the Company. Please see below snippets. The status of the said company is 6.
But if you notice on the 2nd snip, the status is 3 which is the Id of the Company.
I also have this code in OnModelCreating.
modelBuilder.Entity<Company>()
.HasOne<Status>()
.WithMany()
.HasForeignKey(p => p.Status_Id);
This is the reason why I get that behavior. But if I removed this, the Status property is gets NULL.
Update #2
Just fixed my issue. I need to change the Company property from public Company Company { get;set; } to public List Companies { get;set; }. Then add the suggested answer Include`.
[Table("Status")]
public class Status
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public List<Company> Companies { get; set; }
}
You have to add the .Include() method to join your status table in your result like so:
_dbContext.Companies.Include(c => c.Status).ToList()
I am using Entity Framework Core 2.0.1 and I have the following models
public class Article
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Key]
public int Id { get; set; }
[Required]
public string Title { get; set; }
public string Slug { get; set; }
public int Approved { get; set; }
public DateTime ArticleDate { get; set; }
// ... some other fields
public virtual ICollection<ArticleCategoryRelation> ArticleCategoryRelations { get; set; }
}
public class ArticleCategory
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public string Description { get; set; }
//... soem other fields
[ForeignKey("ArticleCategoryParent")]
public int? ArticleCategoryParentID { get; set; }
public virtual ArticleCategory ArticleCategoryParent { get; set; }
public virtual ICollection<ArticleCategory> SubCategories { get; set; }
public virtual ICollection<ArticleCategoryRelation> ArticleCategoryRelations { get; set; }
}
public class ArticleCategoryRelation
{
[Column(Order = 0)]
public int ArticleId { get; set; }
public Article Article { get; set; }
[Column(Order = 1)]
public int ArticleCategoryId { get; set; }
public ArticleCategory ArticleCategory {get; set;}
}
Every article belongs to one or more categories. Categories might have parent category.
I want to get from database last two articles (where Approved = 1) with related category details, for each category that belongs to a parent category which id is given as input.
I have tried but with no success. I can't filter results of an .Include() entity. Is it possible... or I don't know how to do it?
All my data are accessed through entity framework with appContext (the context used to get entities from database). Can I achieve what I want through entity framework core (lambda expression is preferred over Linq if possible), or should I use ADO.NET library (which I know how to execute custom queries).
P.S. I want to get data only to show in the view... no edit is needed.
You don't actually need to include here at all, as far as I can tell. Whenever you use data from a nav property, EF will go get the data from that table, as best it can filter it.
var CategoriesUnderParent = AppContext.ArticleCategories
.Where(c => c.ArticleCategoryParent == {parent});
foreach(var category in CategoriesUnderParent)
{
var ArticlesAllowed = category.ArticleCategoryRelations
.Where(acr => acr.Article.Approved == 1).Select(a => a.Article);
var ArticlesPicked = ArticlesAllowed
.OrderByDescending(ar => ar.ArticleDate)
.Take(2);
// Do something with your data
}
I currently have an employee model
public string FirstName { get; set; }
public string LastName { get; set; }
public virtual ICollection<StateLicenseType> Licenses { get; set; }
and a License Type Model
public class StateLicenseType
{
public int StateLicenseTypeId { get; set; }
public string State { get; set; }
public string LicenseName { get; set; }
public virtual Employee Employee { get; set; }
}
This relationship can be one to many, but I also need to add some information to the license when saved. I need to be able to store the employees unique license number and have not been able to find out how to do this while searching around. Is there a way to have Entity Framework add a column to a join table and then even if I have to, update it myself?
Is there a better/different way to model this relationship with EF?
In an old DB the table was created like this,
CREATE TABLE `nmlsstatelicenses` ( `peopleid` int(11) DEFAULT NULL, `statelicensetypeid` int(11) DEFAULT NULL, `licensenumber` varchar(25) DEFAULT NULL)
You need to create a third entity which will be a linking entity (like a linking table in many-to-many relationships in database. Here is an example: many-to-many relationships with additional information.
So you would have the following entities in your model:
public Employee
{
public string EmployeeId { get;set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public virtual ICollection<LicenseRegistration> RegisteredLicenses { get; set; }
}
public LicenseType
{
public int StateLicenseTypeId { get; set; }
public string State { get; set; }
public string LicenseName { get; set; }
public virtual ICollection<LicenseRegistration> RegisteredLicenses { get; set; }
}
public LicenseRegistration
{
//properties for the additional information go here
/////////////////////////////////////////////////////
public int EmployeeId {get;set;}
[ForeignKey("EmployeeId")]
public Employee Employee {get;set;}
public int LicenseTypeId {get;set;}
[ForeignKey("LicenseTypeId")]
public LicenseType {get;set;}
}
Then, in your DBContext file, you will need to define 1-to-many relationship between Employee and LicenseRegistration, and between LicenseType and LicenseRegistration.
Hope this helps!
UPDATE
Here is how you would set up the relationships:
modelbuilder.Entity<LicenseRegistration>()
.HasRequired(lr => lr.LicenseType)
.WithMany(lt => lt.RegisteredLicenses)
.HasForeignKey(lr => lr.LicenseTypeId);
modelbuilder.Entity<LicenseRegistration>()
.HasRequired(lr => lr.Employee)
.WithMany(e => e.RegisteredLicenses)
.HasForeignKey(lr => lr.EmployeeId);
Forewarning: I know approximately nothing when it comes to MVC/Entity Framework/Linq queries.
I'm having an issue when I try to query the database. Here's the query I'm using:
int? UserId = db.StudentModel
.Where(c => c.UserName == certUserName)
.Select(c => c.UserId)
.FirstOrDefault();
When it searches the database, it successfully retrieves the UserId.
The problem is that I then use the following query:
CompletionsModel student = db.Completions.Find(UserId);
When I do this, it throws an inner exception that states
{"Invalid column name 'UserProfile_UserId'."}
The weird thing is that when I go to my code and mouse over the 'db' part of the command to see what data it's holding, it has CourseModel, StudentModel, and Completions (though the model's actual filename is CompletionsModel - is that a clue?), so it seems like they're linked properly.
Here's the code for my three models and the database context.
CompletionsModel (UserProfile is white text in my code; not sure why it's teal here Same with UserId and CompletionDate):
[Table("Completion")]
public class CompletionsModel
{
[Key]
public int UserId { get; set; }
public string PRD_NUM { get; set; }
public DateTime CompletionDate { get; set; }
public virtual CourseModel PRD { get; set; }
public virtual StudentModel UserProfile { get; set; }
}
CourseModel:
[Table("PRD")]
public class CourseModel
{
[Key]
public string PRD_NUM { get; set; }
public string PRD_TIT { get; set; }
//because any number of students can be enrolled in one course
public virtual ICollection<CompletionsModel> CompletionsModel { get; set; }
}
StudentModel:
[Table("UserProfile")]
public class StudentModel
{
[Key]
public int UserId { get; set; }
public string UserName { get; set; }
public virtual ICollection<CompletionsModel> CompletionsModel { get; set; }
}
DBContext:
public class ClassContext : DbContext
{
public ClassContext()
: base("DefaultConnection")
{
}
public DbSet<StudentModel> StudentModel { get; set; }
public DbSet<CompletionsModel> Completions { get; set; }
public DbSet<CourseModel> CourseModel { get; set; }
}
And finally, an image of my database layout - maybe this will help things along, too:
I'm too at the beginning of Entity Framework, but what does irritate me is, that you have kind of foreign key relationship between Completion and UserProfile, without really defining, a int column as foreign key in your Completion Table.
You could try to change
public virtual StudentModel UserProfile { get; set; }
to something like
public virtual int StudentId { get; set; }
[ForeignKey("StudentId")]
public virtual StudentModel UserProfile { get; set; }
The same for PRD
But maybe a change in your database is not what you want.
What you could also do, is to remove these lines
public virtual CourseModel PRD { get; set; }
public virtual StudentModel UserProfile { get; set; }
Hope that helps.
EDIT:
I guess the problem is, that you are missing the ForeignKey Attribute at your UserProfile property in your Completions table.
So use
[ForeignKey("UserId")]
public virtual StudentModel UserProfile { get; set; }
instead of
public virtual StudentModel UserProfile { get; set; }
if the UserIds are representing the same user
I'm developing a Class library using C# using the latest version of Entity Framework and VS2010. I have this class:
public class User
{
public int UserId { get; set; }
public String Name { get; set; }
public int Age { get; set; }
public String City { get; set; }
public String Country { get; set; }
public String Email { get; set; }
public String InterestIn { get; set; }
public List<User> Friends { get; set; }
public List<User> FromWhomIsFriend { get; set; }
public List<Activity> WantsToDo { get; set; }
public List<Message> MessagesSent { get; set; }
public List<Message> MessagesReceived { get; set; }
}
EF has generated these two tables on SQLEXPRESS:
I have three questions:
How can I rename the table dbo.UserUsers to dbo.UserFriends?
How can I rename its two columns to UserId and FriendId?
How can I set columns UserId and FriendId as PK for dbo.UserFriends table?
NOTE: This is my first time working with EF Code First.
The easiest option is to create this table in your model. If EF detect such table it won't create another one.
To customize column name look here: How to customize foreign key column name using Entity Framework Code-first