I am trying to set up a SQLite database using SQLite.Net and SQLiteNetExtensions. I cant seem to get the foreign keys to create in the database. I have dropped all tables and used the model classes to recreate them again. I have checked the pragma in SQLite manager and foreign keys are turned on. In my example, a plot can have many trees. Any suggestions on what i might be missing?
public class Tree
{
[PrimaryKey, AutoIncrement]
public int TreeId { get; set; }
[NotNull]
public int TreeNumber { get; set; }
[NotNull]
public double Dbhob { get; set; }
public double? Height { get; set; }
[NotNull,Default(value: false)]
public bool? HeightTree { get; set; }
public string QualityCode { get; set; }
[ForeignKey(typeof(Plot))]
public int PlotId { get; set; }
[ManyToOne]
public Plot PlotInverse { get; set; }
}
public class Plot
{
[PrimaryKey, AutoIncrement]
public int PlotId { get; set; }
[NotNull, Unique]
public System.Guid PlotGuid { get; set; }
[NotNull, MaxLength(60)]
public string Strata { get; set; }
[NotNull, MaxLength(60)]
public string PlotNumber { get; set; }
public DateTime MeasureDate { get; set; }
[MaxLength(70)]
public String AssessorLead { get; set; }
[MaxLength(60)]
public String AssessorCrew { get; set; }
[Default(value: 0)]
public double PlotArea { get; set; }
public double BasalArea { get; set; }
[OneToMany("PlotId","PlotId")]
public List<Tree> Trees { get; set; }
}
Foreign keys attributes are not created in the sqlite database as sqlite-net doesn't have support for Foreign Keys and SQLite-Net Extensions is built on top of it. They are used in runtime to save and load related objects.
As a side note, you should change this line:
[OneToMany("PlotId","PlotId")]
public List<Tree> Trees { get; set; }
To this:
[OneToMany("PlotId","PlotInverse")]
public List<Tree> Trees { get; set; }
or remove it all together and let auto-discovery do its magic:
[OneToMany]
public List<Tree> Trees { get; set; }
Related
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 am trying to save a foreign key in 2 columns of a row. For some reason, this is acting wonky because some of the navigation properties are showing up as columns in my table... Here is the model. What am I doing wrong?
public class BorrowedPerson
{
public int BorrowedPersonID { get; set; }
public Nullable<int> PersonID { get; set; }
public Nullable<int> CompanyID { get; set; }
public Nullable<int> TempCompanyID { get; set; }
public virtual Person Person { get; set; }
public virtual Company Company { get; set; }
public virtual Company TempCompanyID { get; set; }
}
I figured it out... Very simple answer. When you are specifying more than one navigation property to the same type, it requires you to manually specify the foreign key like so.
public class BorrowedPerson
{
public int BorrowedPersonID { get; set; }
public Nullable<int> PersonID { get; set; }
public Nullable<int> CompanyID { get; set; }
public Nullable<int> TempCompanyID { get; set; }
public virtual Person Person { get; set; }
[ForeignKey("CompanyID ")]
public virtual Company Company { get; set; }
[ForeignKey("TempCompanyID")]
public virtual Company TempCompanyID { get; set; }
}
I have two simple tables as follow:
public class MediaPartner
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public string PhoneNumber { get; set; }
public string CompanyName { get; set; }
public double Lat { get; set; }
public double Lng { get; set; }
public DateTime InsertedUtc { get; set; }
}
public class ImageGroup
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
public List<MediaPartner> IdMediaPartner { get; set; }
public string ImagePath { get; set; }
public bool IsSent { get; set; }
public DateTime InsertedUtc { get; set; }
}
The problem:
public List< MediaPartner > IdMediaPartner { get; set; }
OR
public MediaPartner IdMediaPartner { get; set; }
does not compile.
My question is: Is there a way to build one-to-many relationship between these two tables?
Thank you!
SQLite-net only provides cross-table referencing using indexing like:
public class Stock
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
[MaxLength(8)]
public string Symbol { get; set; }
}
public class Valuation
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
[Indexed]
public int StockId { get; set; }
public DateTime Time { get; set; }
public decimal Price { get; set; }
}
There is at least one extension to sqlite-net which allows OneToMany attributes to be declared - see https://bitbucket.org/twincoders/sqlite-net-extensions which enables code like:
public class Stock
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
[MaxLength(8)]
public string Symbol { get; set; }
[OneToMany] // One to many relationship with Valuation
public List<Valuation> Valuations { get; set; }
}
public class Valuation
{
[PrimaryKey, AutoIncrement]
public int Id { get; set; }
[ForeignKey(typeof(Stock))] // Specify the foreign key
public int StockId { get; set; }
public DateTime Time { get; set; }
public decimal Price { get; set; }
[ManyToOne] // Many to one relationship with Stock
public Stock Stock { get; set; }
}
I'm not sure of the exact implementation of this - e.g. I don't know if this uses real FOREIGN KEY constraints - but the code is open source, is under active development, has mvvmcross plugin support built-in, is cross platform and is available for forking and for contributions.
I have an model like this:
public class EquipmentEmployee
{
public int EquipmentEmployeeID { get; set; }
public int EmployeeID { get; set; }
public Employee Employee { get; set; }
public int EquipmentID { get; set; }
public Equipment Equipment { get; set; }
public int RequisitionID { get; set; }
public Requisition Requisition { get; set; }
public DateTime From { get; set; }
public DateTime To { get; set; }
public string Comment { get; set; }
}
I use Mvc scaffolding for creating my controllers, repositories and views. Int the create View I'm not able to POST since I dont have values for "to" and "RequisitionID". I have not added [Required] to them. Is this possible? To POST and have those two null?
You should declare optional fields using a nullable type
public int? RequisitionID { get; set; }
To accept the null values you can use the following solution.
public int? RequisitionID { get; set; }