实体框架在知道父项的情况下插入子项记录

Question

I have this problem where I am inserting a child record and in the database the navigation column is null instead of referencing the parents Id .

How can I fix this?

There will only ever be 1 record in the AdminConfiguration Table

Model

public class AdminConfiguration : Entity
{
    public virtual List<ApplicationConfiguration> ApplicationConfiguration { get; set; }
}

Child

public class ApplicationConfiguration : Entity
{
    public Applications Application { get; set; }
    public string ApiKey { get; set; }
    public string IpAddress { get; set; }
    public int Port { get; set; }
    public string HttpScheme { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
}

Insert code

public ApplicationConfiguration Insert(ApplicationConfiguration entity)
{
    Db.ApplicationConfiguration.Add(entity);
    Db.SaveChanges();
    return entity;
}

What the DB looks like after insert:

ID | Other columns | AdminConfiguration_Id
1  | Other values  | NULL

Answer 1

You need an appropriate navigation property on your ApplicationConfiguration entity so EF can map the relationship, personally I would also create a foreign key property as below, as it often easier to just specify the related entity ID rather than having to populate the navigation property.

public class ApplicationConfiguration : Entity
{
    public Applications Application { get; set; }
    public string ApiKey { get; set; }
    public string IpAddress { get; set; }
    public int Port { get; set; }
    public string HttpScheme { get; set; }
    public string Username { get; set; }
    public string Password { get; set; }
    public virtual AdminConfiguration AdminConfiguration { get; set; }
    [ForeignKey("AdminConfiguration")]
    public int AdminConfigurationId { get; set; }
}

This will get rid of the AdminConfiguration_Id column and instead create a AdminConfigurationId columns that will map to the property on your class.