public class Article
{
public List<Category> _ArticleCategory;
public Article()
{
_ArticleCategory = new List<Category>();
}
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ArticleID { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string Content { get; set; }
public int Viewed { get; set; }
public DateTime LastUpdatedDate { get; set; }
public bool IsDeleted { get; set; }
public virtual List<Category> Categories { get; set; }
public virtual List<Tag> Tags { get; set; }
public virtual List<Comment> Comments { get; set; }
}
// I want to take Articles which has more than 1 Category
var result = _context.Articles.Where(a => a.Categories.Count > 1).ToList();
There is my Article Class and my code to take Articles.There i no problem from _Context or somewhere else. It is giving me all Articles.
How can i make conditions for that ?
Thanks Guys..
Thanx everybody..
I solved the proplem..
public virtual List<Category> Categories { get; set; }
public virtual List<Tag> Tags { get; set; }
public virtual List<Comment> Comments { get; set; }
//this.Configuration.LazyLoadingEnabled = false;
I should open this property when ı want to use virtual list options.Thanx again.. Happy Coding :)
Related
print("Hello World !");
I'm a beginner into the .NET world, i'm trying to use entity framework but i have a problem, my relations entities are not loaded, i followed the microsoft documentation but.
Here are my models :
[Table("Path")]
public class Path
{
[Key]
public int PathId { get; set; }
[Required]
public string Title { get; set; }
public List<Image> Images { get; set; }
[Required]
public string Description { get; set; }
[Required]
public float LocationX { get; set; }
[Required]
public float LocationY { get; set; }
[Required]
public string QrCode { get; set; }
public List<Mark> Marks { get; set; }
}
[Table("Mark")]
public class Mark
{
[Key]
public int MarkId { get; set; }
public int Value { get; set; }
public int PathForeignKey { get; set; }
[ForeignKey("PathForeignKey")]
public Path Path { get; set; }
}
[Table("Image")]
public class Image
{
[Key]
public int ImageId { get; set; }
[Required]
public string Name { get; set; }
public string Description { get; set; }
public int PathForeignKey { get; set; }
[ForeignKey("PathForeignKey")]
public Path Path { get; set; }
[Required]
public string Source { get; set; }
}
For me, everything is ok, i even have the correct entries into my database :
database entries
But my relation dont load when i'm reading database into my controller.
[HttpGet]
public IEnumerable<Path> GetAll()
{
return _context.Paths.ToList();
}
results
I'm sorry, i guess it is probably a stupid beginner error but i dont see what i did wrong. I tried with various database system, with virtual or not ...
Mark your navigation properties as virtual. For example:
[Table("Mark")]
public class Mark
{
[Key]
public int MarkId { get; set; }
public int Value { get; set; }
public int PathForeignKey { get; set; }
[ForeignKey("PathForeignKey")]
public virtual Path Path { get; set; } //Added virtual keyword
}
and a second way to load navigation properties is to use Include while fetching data:
return _context.Marks.Include(x => x.Path).ToList();
I have a many to one relationship between Categories and News.
The problem I'm having is that EF keeps adding a foreign key colum to my table which I dont want!
News class
public class News
{
public News()
{
}
[Key]
public int NewsID { get; set; }
public int PublishedByID { get; set; }
public string PublishedByFullName { get; set; }
public string PublishedByEmail { get; set; }
public DateTime DatePublished { get; set; }
public string Title { get; set; }
public string PreviewText { get; set; }
public string BlobName { get; set; }
public virtual Category Category { get; set; }
}
Categories class
public class Category
{
public Category()
{
News = new HashSet<News>();
}
[Key]
public int CategoryID { get; set; }
public string Name { get; set; }
public string CategoryTypeName { get; set; }
public virtual ICollection<News> News { get; set; }
}
Database
My question
How do I remove Category_CategoryID in News table?
I'm guessing i'm missing some code in my OnModelCreating method.
You need to add id field in News class to reference Category.
public class News
{
[Key]
public int NewsID { get; set; }
public int CategoryID { get; set; } // added
public int PublishedByID { get; set; }
public string PublishedByFullName { get; set; }
public string PublishedByEmail { get; set; }
public DateTime DatePublished { get; set; }
public string Title { get; set; }
public string PreviewText { get; set; }
public string BlobName { get; set; }
public virtual Category Category { get; set; }
}
public class Category
{
[Key]
public int CategoryId { get; set; }
public int ParentCategoryId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public int Status { get; set; }
public virtual ICollection<Category> ParentCategories { get; set; }
public virtual ICollection<ImageSet> ImageSets { get; set; }
[ForeignKey("ParentCategoryId")]
public virtual Category ParentCategory { get; set; }
}
public class ImageSet
{
[Key]
public int ImageSetId { get; set; }
public int CategoryId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string InsertDate { get; set; }
public int Status { get; set; }
public virtual ICollection<Image> Images { get; set; }
[ForeignKey("CategoryId")]
public virtual Category Category { get; set; }
}
public class Image
{
[Key]
public int ImageId { get; set; }
public int ImageSetId { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public string ThumbImageUrl { get; set; }
public string InsertDate { get; set; }
public int Status { get; set; }
[ForeignKey("ImageSetId")]
public virtual ImageSet ImageSet { get; set; }
}
Context:
public DbSet<Category> Categories { get; set; }
public DbSet<Image> Images { get; set; }
public DbSet<ImageSet> ImageSets { get; set; }
error page:Introducing FOREIGN KEY constraint 'FK_dbo.ImageSets_dbo.Categories_CategoryId' on table 'ImageSets' may
cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or
ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could
not create constraint. See previous errors.
Whats the problem?
You need to add this:
modelBuilder.Entity<ImageSet>()
.HasRequired(is => is.Category)
.WithMany(c => c.ImageSets)
.WillCascadeOnDelete(false);
Here are good explanations of why this is happening :
https://stackoverflow.com/a/19390016/1845408
https://stackoverflow.com/a/17127512/1845408
When calling the method directly below I get a ObjectDisposedException when calling Mapper.Map with the retrieved list.
System.ObjectDisposedException: The ObjectContext instance has been disposed and can no longer be used for operations that require a connection.
public IEnumerable<Models.Provider> Get(string owner)
{
List<Data.Models.Provider> providers;
using (var db = new Data.ProviderDirectoryContext())
{
providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
}
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
I previously had the code like this (below), I wasn't getting an error, but the database was getting pounded when doing the mapping, and it was taking too long. I don't want to hit the database, when doing the mapping.
public IEnumerable<Models.Provider> Get(string owner)
{
using (var db = new Data.ProviderDirectoryContext())
{
var providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
}
How can I retrieve all the data before doing the mapping?
Here is the DbContext and the Data.Models.Provider for your reference.
public class ProviderDirectoryContext : DbContext
{
public DbSet<Owner> Owners { get; set; }
public DbSet<Location> Locations { get; set; }
public DbSet<LocationAuditLog> LocationAuditLog { get; set; }
public DbSet<Office> Offices { get; set; }
public DbSet<OfficePhoneNumber> OfficePhoneNumbers { get; set; }
public DbSet<OfficeAuditLog> OfficeAuditLog { get; set; }
public DbSet<OfficeDay> OfficeDays { get; set; }
public DbSet<Provider> Providers { get; set; }
public DbSet<ProviderPhoneNumber> ProviderPhoneNumbers { get; set; }
public DbSet<ProviderAuditLog> ProviderAuditLog { get; set; }
public DbSet<ProviderType> ProviderTypes { get; set; }
public DbSet<ProviderSpecialty> ProviderSpecialties { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Provider>().HasRequired(cn => cn.Owner).WithMany().WillCascadeOnDelete(false);
modelBuilder.Entity<Office>().HasRequired(cn => cn.Owner).WithMany().WillCascadeOnDelete(false);
}
}
public class Provider
{
public int Id { get; set; }
public int OwnerId { get; set; }
public virtual Owner Owner { get; set; }
public int? ProviderTypeId { get; set; }
public virtual ProviderType ProviderType { get; set; }
public int? ProviderSpecialtyId { get; set; }
public virtual ProviderSpecialty ProviderSpecialty { get; set; }
[Required]
[StringLength(75)]
public string FirstName { get; set; }
[StringLength(75)]
public string MiddleName { get; set; }
[Required]
[StringLength(75)]
public string LastName { get; set; }
[StringLength(100)]
public string EmailAddress { get; set; }
public virtual ICollection<ProviderPhoneNumber> PhoneNumbers { get; set; }
public string Note { get; set; }
public DateTime? InactiveOn { get; set; }
public int OfficeId { get; set; }
public virtual Office Office { get; set; }
public virtual ICollection<ProviderAuditLog> AuditLog { get; set; }
[Required]
public DateTime CreatedOn { get; set; }
[Required]
[StringLength(75)]
public string CreatedBy { get; set; }
[Required]
public DateTime ModifiedOn { get; set; }
[Required]
[StringLength(75)]
public string ModifiedBy { get; set; }
}
Thanks for the help!
The problem is that the Models.Provider class contains other classes like Models.Office, and Models.PhoneNumbers that were not eagerly loaded by the query. In addition to that, the Models.Provider class needs to be flattened. The Mapper wants to recursively map everything, and it keeps going down to the next class. For example, Provider.Office.Location.Offices.
The solution is to flatten Models.Provider and add .Include() to the query so it eagerly loads the data required.
I'll clean this up a bit more, but this is currently working.
public IEnumerable<Models.Provider> Get(string owner)
{
List<Data.Models.Provider> providers;
using (var db = new Data.ProviderDirectoryContext())
{
providers = db.Providers
.Where(p => p.Owner.Name == owner)
.Include("ProviderType")
.Include("ProviderSpecialty")
.Include("Office")
.Include("PhoneNumbers")
.ToList();
}
var dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
return dtoProviders;
}
public class Provider
{
public int Id { get; set; }
public int OwnerId { get; set; }
public int OfficeId { get; set; }
public string OfficeName { get; set; }
public int? ProviderTypeId { get; set; }
public string ProviderTypeName { get; set; }
public int? ProviderSpecialtyId { get; set; }
public string ProviderSpecialtyName { get; set; }
public string FirstName { get; set; }
public string MiddleName { get; set; }
public string LastName { get; set; }
public string EmailAddress { get; set; }
public virtual ICollection<PhoneNumber> PhoneNumbers { get; set; }
public string Note { get; set; }
public DateTime? InactiveOn { get; set; }
public DateTime CreatedOn { get; set; }
public string CreatedBy { get; set; }
public DateTime ModifiedOn { get; set; }
public string ModifiedBy { get; set; }
}
I am not sure how much this will help with performance but declaring the variable you don't want to dispose outside the using statement should fix your dispose exception.
public IEnumerable<Models.Provider> Get(string owner)
{
IEnumerable<Models.Provider> dtoProviders;
using (var db = new Data.ProviderDirectoryContext())
{
List<Data.Models.Provider> providers = db.Providers.Where(p => p.Owner.Name == owner).ToList();
dtoProviders = Mapper.Map<List<Data.Models.Provider>, List<Models.Provider>>(providers);
}
return dtoProviders;
}
I get a common error that probably is easy to solve but I have no clue how. This is the message I get.
The column name is not valid. [ Node name (if any) = Extent1,Column name = Blog_BlogId ]
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.Data.SqlServerCe.SqlCeException: The column name is not valid. [ Node name (if any) = Extent1,Column name = Blog_BlogId ]
This is my classes representing my entities:
public class BlogContext : DbContext
{
public BlogContext()
: base("SqlCeServices")
{
}
public DbSet<User> Users { get; set; }
public DbSet<Blog> Blogs { get; set; }
public DbSet<Post> Posts { get; set; }
public DbSet<Category> Categories { get; set; }
public DbSet<Tag> Tags { get; set; }
}
[Table("aspnet_Users")]
public class User
{
[Required]
public Guid ApplicationId { get; set; }
[Required]
public Guid UserId { get; set; }
[Required]
public string UserName { get; set; }
[Required]
public string LoweredUserName { get; set; }
public string MobileAlias { get; set; }
[Required]
public bool IsAnonymous { get; set; }
[Required]
public DateTime LastActivityDate { get; set; }
}
public class Blog
{
[Key]
public int BlogId { get; set; }
[Required]
public string Name { get; set; }
public string Url { get; set; }
public int Rating { get; set; }
public virtual ICollection<User> Editors { get; set; }
public virtual ICollection<Post> Posts { get; set; }
}
public class Post
{
[Key]
public int PostId { get; set; }
[Required, MaxLength(200)]
public string Title { get; set; }
public string Content { get; set; }
public string Abstract { get; set; }
public DateTime DateCreated { get; set; }
public DateTime DateLastEdited { get; set; }
public virtual User UserId { get; set; }
public virtual ICollection<Category> Categories { get; set; }
public virtual ICollection<Tag> Tags { get; set; }
public virtual Blog BlogId { get; set; }
}
public class Category
{
[Key]
public int CategoryId { get; set; }
[Required, MaxLength(200)]
public string Title { get; set; }
public string Description { get; set; }
public virtual ICollection<Post> Posts { get; set; }
public virtual Category ParentCategory { get; set; }
public virtual Blog BlogId { get; set; }
}
public class Tag
{
[Key]
public int TagId { get; set; }
[Required, MaxLength(200)]
public string Title { get; set; }
public virtual Blog BlogId { get; set; }
}
Consider changing your Post class so that BlogId references the FK to the associated Blog instead of the Blog object itself. Add a new property Blog to reference the actual Blog object.
public class Post
{
[Key]
public int PostId { get; set; }
[Required, MaxLength(200)]
public string Title { get; set; }
public string Content { get; set; }
public string Abstract { get; set; }
public DateTime DateCreated { get; set; }
public DateTime DateLastEdited { get; set; }
public virtual User UserId { get; set; }
public virtual ICollection<Category> Categories { get; set; }
public virtual ICollection<Tag> Tags { get; set; }
public virtual int BlogId { get; set; }
public virtual Blog Blog { get; set; }
}
You can try...ForeignKey annotation
public virtual int BlogId { get; set; }
[ForeignKey("BlogId ")]
public virtual Blog Blog { get; set; }
Detach the connection from DB, Delete any App Data related to application and rebuild and try again, It worked for me.