I think, I've read everything about this error and I tried everything. Here are my models:
Main:
public class Trip
{
public int TripId { get; set; }
public string Name { get; set; }
public string ShortDescription { get; set; }
public string Country { get; set; }
public float BasicPrice { get; set; }
public virtual ICollection<ApartmentType> ApartmentType { get; set; }
public virtual ICollection<TransportMethod> TransportMethod { get; set; }
public virtual ICollection<FeedingType> FeedingType { get; set; }
}
ApartmentType:
public class TransportMethod
{
public int TransportMethodId { get; set; }
public int TripId { get; set; }
public string Name { get; set; }
public float Price { get; set; }
}
FeedingType:
public class FeedingType
{
public int FeedingTypeId { get; set; }
public int TripId { get; set; }
public string Description { get; set; }
public float Price { get; set; }
}
TransportType:
public class TransportMethod
{
public int TransportMethodId { get; set; }
public int TripId { get; set; }
public string Name { get; set; }
public float Price { get; set; }
}
When serializng the Trip entity I get a circular dependency error. Things i tried:
Disable lazy loading in DbContext.
Adding
json.SerializerSettings.PreserveReferencesHandling=Newtonsoft.Json.PreserveReferencesHandling.All; to GLobal.asax
Adding a decorator [IgnoreDataMember] to TripId in every child entity.
Mapping this entity to a ViewModel which doesn't contain the ICollection members. - This worked ok, but at some point I will want to get those lists to the client.
I really don't know what's going on. What am I missing? I really can't spot any circular dependency.
Have you tried adding the [JsonIgnore] attribute to the TripId to the children entities?
http://james.newtonking.com/projects/json/help/html/T_Newtonsoft_Json_JsonIgnoreAttribute.htm
or setting
json.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
Related
Is there someone who will listen to me and help me solve my problem?
I have 3 classes (Product, Lot and Rem):
Each Product has many Lot and each Lot has many Rem.
public class Product {
public int id { get; set; }
public string name { get; set; }
}
public class Lot {
public int id { get; set; }
public decimal price { get; set; }
}
public class Rem {
public int id { get; set; }
public string note { get; set; }
}
From what you described above this is a simple way for related entities in EF.
public class Product {
public int id { get; set; }
public string name { get; set; }
public Lot LotId {get; set; }
public ICollection<Lot> Lots { get; set; }
}
public class Lot {
public int id { get; set; }
public decimal price { get; set; }
public Product ProductId {get; set; }
public Product Product {get; set; }
public Rem RemId {get; set; }
public ICollection<Rem> Rems { get; set; }
}
public class Rem {
public int id { get; set; }
public string note { get; set; }
public Lot LotId {get; set; }
public Lot Lot { get; set; }
}
And the dbcontext class
public class AppDbContext: DbContext
{
public AppDbContext(DbContextOptions<AppDbContext> options): base(options)
{
}
public DbSet<Product> Products { get; set; }
public DbSet<Lot> Lots { get; set; }
public DbSet<Rem> Rems { get; set; }
}
You can find further explanation about relationships in EF from relationships in EF
I'm trying to create a many-to-many relationship between my two tables, but when I run Update-Database command I get this error:
Introducing FOREIGN KEY constraint 'FK_dbo.ExamQuestions_dbo.Questions_Question_Id' on table 'ExamQuestions' 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 or index. See previous errors.
My first entity is :
public class Question
{
public Question()
{
this.Exams = new HashSet<Exam>();
}
[Key]
public int Id { get; set; }
[Required(ErrorMessage="Question is Required")]
[Display(Name="Question")]
[AllowHtml]
public string QuestionText { get; set; }
// public bool IsMultiSelect { get; set; }
public string Hint { get; set; }
public string HelpLink { get; set; }
public int Marks { get; set; }
public byte[] ImageData { get; set; }
[StringLength(50)]
public string MimeType { get; set; }
public byte[] Audio { get; set; }
public int QuestionTypeId { get; set; }
public int TopicId { get; set; }
public int DifficulityLevelId { get; set; }
public int SubjectId { get; set; }
public DifficultyLevel QuestionDifficulity { get; set; }
public Topic Topic { get; set; }
public virtual ICollection<Option> Options { get; set; }
public ICollection<Exam> Exams { get; set; }
}
And the second entity is:
public class Exam
{
public Exam()
{
this.Questions = new HashSet<Question>();
}
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
[Required]
public int Duration { get; set; }
[Required]
public int TotalQuestion { get; set; }
[Required]
public int TotalMarks { get; set; }
public bool SectionWiseTime { get; set; }
public bool QuestionWiseTime { get; set; }
public bool AllQustionRequired { get; set; }
public bool AllowBackForward { get; set; }
public bool SuffleSubjectWise { get; set; }
public bool SuffleOptionWise { get; set; }
public bool GroupSubjectWise { get; set; }
[Required]
public int ExamTypeId { get; set; }
[Required]
public int ExamInstructionId { get; set; }
[Required]
public int DifficultyLevelId { get; set; }
public virtual ExamType ExamType { get; set; }
public virtual ExamInstruction ExamInstruction { get; set; }
public virtual DifficultyLevel DifficultyLevel { get; set; }
public virtual ICollection<Question> Questions { get; set; }
//public virtual ICollection<ExamSchedule> ExamSchedules { get; set; }
}
Can someone tell me where I'm going wrong?
By default, EF has cascading deletes set. This error is warning you that this can cause cascading deletes with many to many relationships. And is probably not what you intend to have happen on a delete/update.
You can remove the OneToManyCascadeDeleteConvention in the OnModelCreating method, or on the fluent mapping for each entity.
Details are provided in this SO Answer
So I am building an online shop using Code-First MVC
So I created this model classes for now (don't take the types of the attributes too serious for now):
Products (Produto):
public Produto()
{
ListaProdutoEncomenda = new HashSet<Produto_Encomenda>();
}
public int ProdutoID { get; set; }
[Required]
[StringLength(50)]
public string Nome { get; set; }
[Required]
public double Preco { get; set; }
[Required]
public double Peso { get; set; }
[Required]
[StringLength(255)]
public string Descricao { get; set; }
[Required]
public double IVA { get; set; }
public string Imagem { get; set; }
public DateTime UltimaAtualizacao { get; set; }
public int Stock { get; set; }
public int CategoriaID {get;set;}
public virtual ICollection<Produto_Encomenda> ListaProdutoEncomenda { get; set; }
}
Encomenda (Order):
public class Encomenda
{
public Encomenda()
{
ListaProdutoEncomenda = new HashSet<Produto_Encomenda>();
}
[Key]
public int IDEncomenda { get; set; }
[Required]
public DateTime DataSubmissao { get; set; }
[Required]
public DateTime DataEnvio { get; set; }
[Required]
public int EstadoEnvioID { get; set; }
[StringLength(50)]
public string NomeDestino { get; set; }
[Required]
public int TipoExpedicaoID { get; set; }
[Required]
public int RegiaoDestinoID { get; set; }
[StringLength(50)]
public string MoradaDestino { get; set; }
[StringLength(50)]
public string CodPostalDestino { get; set; }
[Required]
[StringLength(50)]
public string MoradaFaturacao { get; set; }
[Required]
[StringLength(50)]
public string CodPostalFaturacao { get; set; }
public virtual ICollection<Produto_Encomenda> ListaProdutoEncomenda { get; set; }
}
And the connection table between the produtos (Products) and Encomenda (Order)
public class Produto_Encomenda
{
[Key]
public int IDProduto_Encomenda { get; set; }
[Required]
public string NomeProduto { get; set; }
[Required]
public int Quantidade { get; set; }
[Required]
public float preco { get; set; }
[Required]
public float IVA { get; set; }
public virtual Encomenda Encomenda { get; set; }
public virtual Produto Produto { get; set; }
[ForeignKey("Encomenda")]
public int IDEncomendaFK { get; set; }
[ForeignKey("Produto")]
public int IDProdutoFK { get; set; }
}
So my question is..
Let's pretend that a costumer buys 2 or 3 products or more.
How can I store all this products in a single line of an order?
Cheers and thanks a lot in advance for the time spent reading.
I'm not sure what you mean by "a single line of an order". Each product is a separate line item, and your entities already model this through the many-to-many relationship.
However, in general this setup is a very bad idea. Your order should not be directly related to products. Instead, your order should simply have an order item, and you'll create those order items based on the products that were sold. The reason for this is that products are very likely to change. If a product is removed because it's no longer available, for example, that doesn't negate the fact that it was previously sold in an order. However, in order for referential integrity to be maintained, any orders sold with that product would have to also have their relationship with that product removed. By having an entirely separate entity, i.e. order item, products can come and go, while the already created orders remain unaffected.
I guess you are looking to make a viewmodel
Create a class that contains Products and Encomenda class as property -
Model -
public class MyViewModel
{
public Produto Pinst{get;set;}
public Encomenda Einst{get;set;}
}
Controller or method-
public void SomeMethod()
{
List<MyViewModel> lst = new List<MyViewModel>();
//Now suppose
foreach(var items in listThatGetCreatedWithBuyerproductInfo)
{
MyViewModel obj = new MyViewModel ();
obj.Pinst = new Produto();
obj.Einst = new Encomenda();
//Here goes your properties from item in respected class instances
obj.Pinst.Nome = items.Nome;
obj.Einst.DataSubmissao = items.DataSubmissao;
//when you are done loading add obj to list
lst.Add(obj);
}
}
Hope it Helps if it does not tell me !!
I have got my application up and running using Code first, I am trying to set a 1-1 relationship but when I update-database I get the error "SupplyPointId: Name: Each property name in a type must be unique. Property name 'SupplyPointId' is already defined."
I've tried removing the existing index constraint on SupplyPointAddress.SupplyPointId and that does not help. In the other table its the PK. Any comments really appreciated
public partial class SupplyPoint
{
[Key]
//[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int SupplyPointId { get; set; }
public string SPID { get; set; }
public string SupplyPointName { get; set; }
public int SupplyPointTypeId { get; set; }
public DateTime SupplyPointEffectiveDateTime { get; set; }
public string GazateerRef { get; set; }
public virtual SupplyPointType SupplyPointType { get; set; }
//[ForeignKey("SupplyPointId")]
public virtual SupplyPointAddress SupplyPointAddress { get; set; }
}
public partial class SupplyPointAddress
{
[Key]
//[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int SupplyPointAddressId { get; set; }
public int SupplyPointId { get; set; }
public string D5001_FreeDescriptor { get; set; }
public string D5002_SubBuildingName { get; set; }
public string D5003_BuildingName { get; set; }
public string D5004_BuildingNumber { get; set; }
public string D5005_DependentThoroughfareName { get; set; }
public string D5006_DependentThoroughfareDescriptor { get; set; }
public string D5007_ThoroughfareName { get; set; }
public string D5008_ThoroughfareDescriptor { get; set; }
public string D5009_DoubleDependentLocality { get; set; }
public string D5010_DependentLocality { get; set; }
public string D5011_PostTown { get; set; }
public string D5012_County { get; set; }
public string D5013_Postcode { get; set; }
public virtual SupplyPoint SupplyPoint { get; set; }
}
public System.Data.Entity.DbSet<AscendancyCF.Models.SupplyPoint> SupplyPoints { get; set; }
public System.Data.Entity.DbSet<AscendancyCF.Models.SupplyPointAddress> SupplyPointAddresses { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<SupplyPointAddress>()
.HasOptional<SupplyPoint>(u => u.SupplyPoint)
.WithRequired(c => c.SupplyPointAddress).Map(p => p.MapKey("SupplyPointId"));
base.OnModelCreating(modelBuilder);
}
I moved the foreign key into SupplyPoint table so that the foreign key was being defined as SupplyPointAddressId in SupplyPoint. This worked and allows me to do SupplyPoint.SupplyPointAddress in resultant model
Since you're testing with a real DB. Use some of the
Database Initialization Strategies in Code-First:
public class SchoolDBContext: DbContext
{
public SchoolDBContext(): base("SchoolDBConnectionString")
{
Database.SetInitializer<SchoolDBContext>(new CreateDatabaseIfNotExists<SchoolDBContext>());
//Database.SetInitializer<SchoolDBContext>(new DropCreateDatabaseIfModelChanges<SchoolDBContext>());
//Database.SetInitializer<SchoolDBContext>(new DropCreateDatabaseAlways<SchoolDBContext>());
//Database.SetInitializer<SchoolDBContext>(new SchoolDBInitializer());
}
public DbSet<Student> Students { get; set; }
public DbSet<Standard> Standards { get; set; }
}
(Excerpt from this site)
It is pretty self explanatory.
If there's already a DB created, it just DROPs it.
Happy coding!
How do I model the following using Castle ActiveRecord?
I have two classes, Customer and Task.
I would like to reuse a third class, Note, stored in a Collection in each of the Customer and Task classes.
public class Note
{
public int ID { get; set; }
public string Subject { get; set; }
public string Body { get; set; }
}
public class Customer
{
public int ID { get; set; }
public IList<Note> Notes { get; set; }
}
public class Task
{
public int ID { get; set; }
public IList<Note> Notes { get; set; }
}
I would then like to be able to pass the Notes collection to a Gridview, Listview or Repeater in the relevant ASP.Net page for the Customer or Task classes.
I think what you need is to implement a type hierarchy. You can read about it here.
We settled on the following pattern:
[ActiveRecord]
public class Note
{
[PrimaryKey]
public int ID { get; set; }
[Property]
public string Subject { get; set; }
[Property]
public string Body { get; set; }
[BelongsTo]
public Customer Customer { get; set; }
[BelongsTo]
public Customer Task{ get; set; }
}
[ActiveRecord]
public class Customer
{
[PrimaryKey]
public int ID { get; set; }
[HasMany]
public IList<Note> Notes { get; set; }
}
[ActiveRecord]
public class Task
{
[PrimaryKey]
public int ID { get; set; }
[HasMany]
public IList<Note> Notes { get; set; }
}