如何在Entity Framework Core的多对多关系表中添加项目？

// 实体类
public class Project
{
    public int ProjectId { get; set; }
    public string Name { get; set; }
    public ICollection<ProjectUser> ProjectUsers { get; set; }
}

public class User
{
    public int UserId { get; set; }
    public string Name { get; set; }
    public ICollection<ProjectUser> ProjectUsers { get; set; }
}

public class ProjectUser
{
    public int ProjectId { get; set; }
    public Project Project { get; set; }
    public int UserId { get; set; }
    public User User { get; set; }
}

// DbContext类中的配置
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<ProjectUser>()
        .HasKey(pu => new { pu.ProjectId, pu.UserId });

    modelBuilder.Entity<ProjectUser>()
        .HasOne(pu => pu.Project)
        .WithMany(p => p.ProjectUsers)
        .HasForeignKey(pu => pu.ProjectId);

    modelBuilder.Entity<ProjectUser>()
        .HasOne(pu => pu.User)
        .WithMany(u => u.ProjectUsers)
        .HasForeignKey(pu => pu.UserId);
}

// 添加项目
var project = new Project { Name = "Project 1" };
var user = new User { Name = "User 1" };

var projectUser = new ProjectUser
{
    Project = project,
    User = user
};

context.ProjectUsers.Add(projectUser);
context.SaveChanges();