实体框架代码优先关系保存问题

Question

将新员工保存到数据库时遇到一些麻烦。

项目模型（删除无用字段）：

public class Project{
        public virtual ICollection<EmployeeManager.Employee> Employees { get; set; }
    }

EmployeeManager.Employee 模型：

public class Employee{
        public virtual ApplicationUser User { get; set; }
        public virtual ProjectsManager.Project ProjectObj { get; set; }
    }  

功能：

public async Task AddNewEmployeeAsync(string projectId, string email, string fullname){       
        var projectInfo = await GetByIdAsync(projectId);
        var userInfo = new ApplicationUser();

        if (await _context.Users.AnyAsync(_ => _.Email == email)){
            userInfo = await _context.Users.FirstAsync(_ => _.Email == email);
        }
        else{
            ....
            userInfo = user;
        }

        projectInfo.Employees.Add(new EmployeeManager.Employee{
            User = userInfo
        });

        _context.Entry(projectInfo).State = EntityState.Modified;

        _context.SaveChanges();
    }

毕竟，我的数据库没有任何变化。

为什么？

如果我使用 _context.Employees.Add() -> 它会在数据库中创建新的项目实体。

Answer 1

要使实体框架无需配置 (FluentApi) 即可创建正确的关系（一对多），您需要对 Employee 类进行一些更改

public class Employee
{
    public virtual ApplicationUser User { get; set; }
    public int ProjectId { get; set; } //foreign key maybe a string as defined in your Project class
    public virtual ProjectsManager.Project Project { get; set; }
}