[英]Modeling a many-to-many relationship between 3 tables with Code First
I have the following 3 entities: 我有以下3个实体:
And the relationship goes like 这种关系就像
I got this far: 我到目前为止:
public class User
{
public int Id { get; set; }
public ICollection<Account> Accounts { get; set; }
}
public class Account
{
public int Id { get; set; }
public ICollection<User> Users { get; set; }
}
public class Role
{
public int Id { get; set; }
public string RoleName { get; set; }
public virtual ICollection<User> Users { get; set; }
public virtual ICollection<Account> Accounts { get; set; }
}
Every time an user registers, they also create an account, so I thought of this: 每次用户注册时,他们也会创建一个帐户,所以我想到了这个:
public async Task AddAccountAsync(User user, string accountName)
{
Account account = new Account(user, accountName);
Role role = new Role(Roles.Owner);
Accounts.Add(account);
user.Accounts.Add(account);
Entry(user).State = EntityState.Modified;
await SaveChangesAsync();
}
But I am not sure how to tie the role to the user to the account, so I can get the role an user has in an account. 但我不确定如何将角色与用户绑定到帐户,因此我可以获得用户在帐户中的角色。
For example: 例如:
Consider 3 users and 3 accounts: 考虑3个用户和3个帐户:
Following @IvanStoev's answer, I got this: 按照@ IvanStoev的回答,我得到了这个:
public async Task AddAccountAsync(User user, string accountName)
{
Role role = new Role(Roles.Owner);
Account account = new Account(model.AccountCurrency, model.AccountName, model.Description);
UserAccount uc = new UserAccount
{
User = user,
Account = account,
Role = role
};
account.UserAccounts.Add(uc);
Accounts.Add(account);
user.UserAccounts.Add(uc);
Entry(user).State = EntityState.Modified;
await SaveChangesAsync();
}
Should I be saving the UserAccount object (as a DbContext<UserAccount>
)? 我应该保存UserAccount对象(作为DbContext<UserAccount>
)吗?
- One user can have many accounts 一个用户可以拥有多个帐户
- One account can belong to many users 一个帐户可以属于许多用户
- Each user has a role in an account 每个用户都在帐户中拥有角色
The automatic link table does not work for scenarios like this when you need to associate additional information ( Role
in this case) with the User - Account
link. 当您需要将其他信息(在本例中为Role
)与User - Account
链接相关联时,自动链接表不适用于此类方案。
So instead of automatic many-to-many
association you need to use two one-to-many
associations with explicit link entity like this: 因此,您需要使用与显式链接实体的两个one-to-many
关联,而不是自动many-to-many
关联,如下所示:
Model: 模型:
public class User
{
public int Id { get; set; }
public ICollection<UserAccount> UserAccounts { get; set; }
}
public class Account
{
public int Id { get; set; }
public ICollection<UserAccount> UserAccounts { get; set; }
}
public class UserAccount
{
public int UserId { get; set; }
public int AccountId { get; set; }
public int RoleId { get; set; }
public User User { get; set; }
public Account Account { get; set; }
public Role Role { get; set; }
}
public class Role
{
public int Id { get; set; }
public string RoleName { get; set; }
public ICollection<UserAccount> UserAccounts { get; set; }
}
Configuration: 组态:
modelBuilder.Entity<UserAccount>()
.HasKey(e => new { e.UserId, e.AccountId });
modelBuilder.Entity<UserAccount>()
.HasRequired(e => e.User)
.WithMany(e => e.UserAccounts)
.HasForeignKey(e => e.UserId);
modelBuilder.Entity<UserAccount>()
.HasRequired(e => e.Account)
.WithMany(e => e.UserAccounts)
.HasForeignKey(e => e.AccountId);
modelBuilder.Entity<UserAccount>()
.HasRequired(e => e.Role)
.WithMany(e => e.UserAccounts)
.HasForeignKey(e => e.RoleId);
You can create a new UserAccount
in a several ways. 您可以通过多种方式创建新的UserAccount
。
One way is to add it to one of the child UserAccounts
collections. 一种方法是将其添加到其中一个子UserAccounts
集合中。 In your example, account.UserAccounts.Add(uc);
在您的示例中, account.UserAccounts.Add(uc);
followed by context.Accounts.Add(account)
will automatically add it to context.UserAccounts
, user.UserAccounts
and role.UserAccounts
. 然后是context.Accounts.Add(account)
会自动将其添加到context.UserAccounts
, user.UserAccounts
和role.UserAccounts
。
Another way is to use context.UserAccounts.Add(uc);
另一种方法是使用context.UserAccounts.Add(uc);
in which case it will be automatically added to user
, account
and role
child UserAccounts
collections. 在这种情况下,它将自动添加到user
, account
和role
子UserAccounts
集合中。
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