Question

物业：

我按此顺序有3个表：Company -> Person -> Phone
Company可以有多个Person，可以有多个Phone。
他们都incremental INT为PK。
他们之间有明确的关系，因此Phone有id_phone＆amp; id_company＆amp; id_person PK。{/ li>
使用案例
1. 用户希望添加Company Person Phone。

Answer 1

上下文将跟踪对子集合的添加

var phone = new Phone() { //whatever };
var person = new Person() { //whatever };
person.Phones.Add(phone);

var company = new Company() { //whatever };
company.People.Add(person);

dbContext.Companies.Add(company);
dbContext.SaveChanges();

只要您定义了关系，它就会自动设置正确的外键等。

以下是代码优先的示例

public class Company
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id;
    // other properties
    public virtual Collection<Person> People { get; set; }
}

public class Person
{
    [Key]
    [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
    public int Id;
    // Other properties
    [ForeignKey("Company")]
    public int CompanyId { get; set; }
    public virtual Company Company { get; set; }
    public virtual Collection<Phone> Phones { get; set; }
}

更新：您可以以类似方式添加其他子项，您只需先获取实体

var db = new DbContext();
var company = db.Companies.FirstOrDefault(x => x.Id == 1);
if(company != null)
{
    var person = new Person() { // blah };
    company.People.Add(person);
    db.SaveChanges();
}

Answer 2

只做

company.Persons.Add(new Person
    {
        //set Person properties here but dont worry about PK - EF sorts this out for you
    });

你甚至可以这样做：

company.Persons.Addcnew Person
    {
        //set Person properties here but dont worry about PK - EF sorts this out for you
        PhoneNumbers= new PhoneNumber[]
        {
            new PhoneNumber() {/*..*/ }
        }
    });

使用EF处理嵌套表

2 个答案: