实体框架核心：当IDENTITY_INSERT设置为OFF时，无法为表'Relation'中的Identity列插入显式值

问题描述

我正在建立一个应用程序，当我想将表单插入到表单表中时，出现以下错误：

I'm bulding an application and when I want to insert a form into my form table I get the following error:

这些是我的模型：

表单模型：

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    [ForeignKey("FormType")]
    public int? TypeId { get; set; }
    public virtual FormType Type { get; set; }

    [ForeignKey("FormStatusType")]
    public int? StatusTypeId { get; set; }
    public virtual FormStatusType StatusTknype { get; set; }

    [ForeignKey("Relation")]
    public int? SupplierId { get; set; }
    public virtual Relation Supplier { get; set; }

    [ForeignKey("Relation")]
    public int? CustomerId { get; set; }
    public virtual Relation Customer { get; set; }

    public String SupplierReference { get; set; }
    public Guid ApiId { get; set; }
    public DateTime DueDate { get; set; }
    public FormFile FormFiles { get; set; }
    public String FormName { get; set; }
    public DateTime UploadDate { get; set; }

关系模型：

[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }
    [ForeignKey("FormType")]
    public int? TypeId { get; set; }
    public virtual FormType Type { get; set; }

    [ForeignKey("FormStatusType")]
    public int? StatusTypeId { get; set; }
    public virtual FormStatusType StatusTknype { get; set; }

    [ForeignKey("Relation")]
    public int? SupplierId { get; set; }
    public virtual Relation Supplier { get; set; }

    [ForeignKey("Relation")]
    public int? CustomerId { get; set; }
    public virtual Relation Customer { get; set; }

    public String SupplierReference { get; set; }
    public Guid ApiId { get; set; }
    public DateTime DueDate { get; set; }
    public FormFile FormFiles { get; set; }
    public String FormName { get; set; }
    public DateTime UploadDate { get; set; }

我的上下文如下：

public class DataContext: DbContext
{
    public DataContext(DbContextOptions<DataContext> options): base(options)
    {

    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);
        optionsBuilder.UseSqlServer();
    }

    public DbSet<Relation> Relation { get; set; }
    public DbSet<Setting> Settings { get; set; }
    public DbSet<Notification> Notification { get; set; }
    public DbSet<FormStatusType> FormStatusType { get; set; }
    public DbSet<File> File { get; set; }
    public DbSet<FormFile> FormFile { get; set; }
    public DbSet<FormType> FormType { get; set; }
    public DbSet<Form> Form { get; set; }
    public DbSet<User> User { get; set; }
    public DbSet<RelationUser> RelationUser { get; set; }
    public DbSet<SupplierCustomer> SupplierCustomer { get; set; }

}

我用来添加表单的方法如下所示：

The method I use to add a form looks like this:

 public async Task<Form> AddForm(Form form, int currentUserId)
    {
        try
        {
            if (form != null)
            {
                //huidige gebruiker als supplier aanduiden
                Relation r = await GetCurrentUser(currentUserId);
                form.Supplier = r;
                form.SupplierId = r.Id;

                //form aan de db toevoegen
                _datacontext.Form.Add(form);
                _datacontext.SaveChanges();

                return form;
            }
            else
            {
                return null;
            }
        }
        catch (Exception e)
        {
            LogError(e);
            return null;
        }
    }

获取当前用户方法

 private async Task<Relation> GetCurrentUser(int currentUserId)
    {
        var relation = from r in _datacontext.RelationUser
                       where r.UserId == currentUserId
                       select r.Relation;
        return await relation.FirstOrDefaultAsync();
    }

这是我调用AddForm方法的地方：

This is where I call the AddForm method:

 [HttpPost]
    [Route("addform")]
    [Authorize]
    // api/form/addform
    public async Task<IActionResult> AddForm([FromBody] Form form)
    {
        if (ModelState.IsValid)
        {
            Form f = await _formRepository.AddForm(form, GetUserIdFromToken());

            if(f != null)
            {
                QueueObject qo = new QueueObject()
                {
                    ActionTypeId = 1,
                    FormId = f.Id
                };
                await new QueueHandler().SendMessageToQueue(qo);
            }

            return Ok(f);
        }
        else
        {
            return NotFound("model is niet geldig");
        }
    }

我已经搜索过，但没有找到解决问题的方法

I already searched but found nothing that solved the problem

推荐答案

您的模型存在多个错误。 ForeignKey属性必须指向类中的属性，而不是从属实体的类型：

You have multiple errors on your model. The ForeignKey attribute must point to properties in the class, not to the type of the dependent entity:

//FORM MODEL
[ForeignKey("Type")]
public int? TypeId { get; set; }
public virtual FormType Type { get; set; }

[ForeignKey("StatusTknype")]
public int? StatusTypeId { get; set; }
public virtual FormStatusType StatusTknype { get; set; }

[ForeignKey("Supplier")]
public int? SupplierId { get; set; }
public virtual Relation Supplier { get; set; }

[ForeignKey("Customer")]
public int? CustomerId { get; set; }
public virtual Relation Customer { get; set; }

//RELATION MODEL
[ForeignKey("Type")]
public int? TypeId { get; set; }
public virtual FormType Type { get; set; }

[ForeignKey("StatusTknype")]
public int? StatusTypeId { get; set; }
public virtual FormStatusType StatusTknype { get; set; }

[ForeignKey("Relation")]
public int? SupplierId { get; set; }
public virtual Relation Supplier { get; set; }

[ForeignKey("Customer")]
public int? CustomerId { get; set; }
public virtual Relation Customer { get; set; }

此外，如果您遵循 Convention Over Configuration ，则可以删除仅通过按常规方式命名属性即可完全完成ForeignKeyAttribute的操作：

Also, if you followed Convention Over Configuration, you could drop the ForeignKeyAttribute completely by just naming the properties conventionally:

public int? StatusTypeId { get; set; }
public virtual FormStatusType StatusType { get; set; }

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