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; }
}
Related
Here is my Schema and with two Foreign Key in an intermediate table. I am beginner in Core dotnet so unable to crate API to show the department in the school.
public class DepartmentSchool
{
public int Id { get; set; }
public int DepartmentID { get; set; }
[ForeignKey("DepartmentID")]
public virtual Department Department{ get; set; }
public int SchoolsId { get; set; }
[ForeignKey("SchoolsId")]
public virtual Schools Schools { get; set; }
Here I want to get all department related to school id, how can i get all the department though the School id in dotnetcore API.
Here is the school class entity schema.
public partial class Schools
{
public int ID { get; set; }
public string UicCode { get; set; }
public int SchoolSystemsId { get; set; }
public string BannerUrl { get; set; }
public string Name { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public int UserID { get; set; }
public int? Status { get; set; }
public DateTime? CreatedAt { get; set; }
public int? CreatedBy { get; set; }
public DateTime UpdatedAt { get; set; }
public int? ModifiedBy { get; set; }
[ForeignKey("SchoolSystemsId")]
public PrivateSchoolSystem PrivateSchoolSystems { get; set; }
And more here is the department schema.
public partial class Department
{
public int Id { get; set; }
public string Title { get; set; }
public DateTime CreatedAt { get; set; }
public DateTime UpdatedAt { get; set; }
public int CreatedBy { get; set; }
public int UpdatedBy { get; set; }
public int SchoolSystemsID { get; set; }
[ForeignKey("SchoolSystemsID")]
public virtual PrivateSchoolSystem PrivateSchoolSystems { get; set; }
And I am trying to get a department list in the query in the following controller.
[Route("api/[controller]")]
[ApiController]
public class DepartmentSchoolController : ControllerBase
{
private readonly learning_gpsContext _learning_GpsContext;
public DepartmentSchoolController(learning_gpsContext learning_GpsContext)
{
_learning_GpsContext = learning_GpsContext;
}
[HttpGet("school/{schoolId}/departments")]
public IActionResult GetDepartmentsFromSchool(int schoolId)
{
var school = _learning_GpsContext.Schools.Where(e=>e.Id == schoolId).FirstOrDefault();
if (school == null)
return NotFound();
var departments = _learning_GpsContext.DepartmentSchool
.Where(e=>e.SchoolsId == schoolId).Select(e=>e.Department);
return Ok(departments);
}
For further learning check this tutorial. You should also understand what REST is and for basic questions always take a look at the official documenation.
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
I have implemented asp .net application without Code first approach. now i want to build different system with existing database and code first.
public class EmployeeEntity
{
public int Id { get; set; }
public string ResourceCode { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime DateOfBirth { get; set; }
public int Gender { get; set; }
public int Status { get; set; }
public string NIC { get; set; }
}
now i want to add code first entities.
[Table("ExternalApplicantEntity")]
public class ExternalApplicantEntity
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ApplicantID { get; set; }
//[ForeignKey("EmployeeEntity")]
//public int Created_By { get; set; }
//public virtual EmployeeEntity EmployeeEntity { get; set; }
public string NIC { get; set; }
public string Mobile { get; set; }
public string Institute { get; set; }
how i combine these codes?
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; }
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!