EntityFramework核心Fluent API

Question

I have two tables: EstimationActivity and Activity:

public class EstimationActivity 
{
    public Guid Id { get; set; }

    public Guid EstimateId { get; set; }
    public virtual Estimate Estimate { get; set; }

    public Guid ParentActivityId { get; set; }
    public virtual Activity ParentActivity { get; set; }

    public Guid ActivityId { get; set; }
    public virtual Activity Activity { get; set; }

    public double Duration { get; set; }

    [Range(minimum: 0, maximum: 100)]
    public int Contingency { get; set; }

    public ICollection<Note> Notes { get; set; } = new List<Note>();
}

public class Activity
{
    public Guid Id { get; set; }

    public Guid ActivityTypeId { get; set; }
    public virtual ActivityType ActivityType { get; set; }

    public Guid RfcAreaId { get; set; }
    public virtual RfcArea RfcArea { get; set; }

    [Required]
    [StringLength(maximumLength: 60, MinimumLength = 5)]
    public string Name { get; set; }
}

As you can see there are two foreign keys to the Activity table(class). When I try to add a migration I get:

Introducing FOREIGN KEY constraint 'FK_EstimateActivities_Activities_ParentActivityId' on table 'EstimateActivities' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

I tried to restrict all cascade deletions with this, as I found in few articles:

protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        foreach (var relationship in modelBuilder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys()))
        {
            relationship.DeleteBehavior = DeleteBehavior.Restrict;
        }

        base.OnModelCreating(modelBuilder);
    }

This didn't do the work. How should I go over the error?

Answer 1

Try use attributes [ForeignKey("SomeId")] where you set FK's and [InverseProperty("OtherClass")] overrides this convention and specifies alignment of the properties.

    public class EstimationActivity
{
    public Guid Id { get; set; }

    public Guid EstimateId { get; set; }
    public virtual Estimate Estimate { get; set; }

    public Guid ParentActivityId { get; set; }

    [ForeignKey("ParentActivityId")]
    public virtual Activity ParentActivity { get; set; }

    public Guid ActivityId { get; set; }

    [ForeignKey("ActivityId")]
    public virtual Activity Activity { get; set; }

    public double Duration { get; set; }

    [Range(minimum: 0, maximum: 100)]
    public int Contingency { get; set; }

    public ICollection<Note> Notes { get; set; } = new List<Note>();
}

public class Activity
{
    public Guid Id { get; set; }

    public Guid ActivityTypeId { get; set; }
    public virtual ActivityType ActivityType { get; set; }

    public Guid RfcAreaId { get; set; }
    public virtual RfcArea RfcArea { get; set; }

    [Required]
    [StringLength(maximumLength: 60, MinimumLength = 5)]
    public string Name { get; set; }


    [InverseProperty("ParentActivity")]
    public virtual EstimationActivity EstimationParentActivity { get; set; }
    [InverseProperty("Activity")]
    public virtual EstimationActivity EstimationActivity { get; set; }
}