我正在创建一个使用自己的数据库表的类库，该数据库表将使用CodeFirst生成。类库定义了模型，需要DbContext来向其添加记录。但是，如何在编译时不知道应用程序自己的db上下文的情况下这样做呢？
应用程序需要将此行添加到他自己的db上下文中：
public DbSet<MyClassLibraryRecords> MyClassLibraryRecords { get; set; }
但是他需要以某种方式将应用程序数据库上下文提供给类库，以便我可以访问MyClassLibraryRecords来执行app_context.MyClassLibraryRecords.Add(record);？
我是否必须使用回调方法，或者应用程序将覆盖的方法来实际存储在数据库中？我不愿意，如果我能在课程库中完成所有工作会更容易......
答案 0 :(得分：2)
您需要构建自己的DBContext，以便实体框架了解您所属域中的类。
CREATE TABLE [dbo].[account](
[account_id] [int] IDENTITY(1,1) NOT NULL,
[name] [nvarchar](50) NOT NULL,
CONSTRAINT [PK_dbo.account] PRIMARY KEY CLUSTERED
(
[account_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[address](
[address_id] [int] IDENTITY(1,1) NOT NULL,
[account_id] [int] NOT NULL,
[full_address] [nvarchar](256) NOT NULL,
CONSTRAINT [PK_dbo.address] PRIMARY KEY CLUSTERED
(
[address_id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[address] WITH CHECK ADD CONSTRAINT [FK_dbo.address_dbo.account_account_id] FOREIGN KEY([account_id])
REFERENCES [dbo].[account] ([account_id])
-------------------------------------------------------
db connection string
<add name="accountDB" connectionString="data source=.; initial catalog=test; integrated security=true;" providerName="System.Data.SqlClient" />
---------------------------------------------------
using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using System.Linq;
using System.Data.Entity;
using System.Data.Entity.ModelConfiguration;
/// <summary>
/// Define my domain.
/// </summary>
public class Account
{
public Account()
{
this.Addresses = new List<Address>();
}
public int? AccountID { get; set; }
public string Name { get; set; }
public virtual ICollection<Address> Addresses { get; set; }
}
public class Address
{
public int? AddressID { get; set; }
public int AccountID { get; set; }
public string FullAddress { get; set; }
}
public interface IAccountService
{
Account GetAccount(int accountID);
void SaveAccount(Account account);
}
public interface IAccountRepository
{
IQueryable<Account> GetAccounts();
void UpdateAccount(Account account);
void CreateAccount(Account account);
}
public class AccountService : IAccountService
{
private IAccountRepository _repository;
public AccountService(IAccountRepository repository)
{
this._repository = repository;
}
public Account GetAccount(int accountID)
{
//you can do some validation. for ex) if we pass the user's name, we can see if they have access rights to the system, module, and data
return (from acc in this._repository.GetAccounts().AsNoTracking()
where acc.AccountID == accountID
select acc).FirstOrDefault();
}
public void SaveAccount(Account account)
{
//apply your business rules such as validating the data, user access rights, and etc
if (account.AccountID.HasValue)
{
this._repository.UpdateAccount(account);
}
else
{
this._repository.CreateAccount(account);
}
}
}
/// <summary>
/// Data access layer.
///
/// This layer knows about your data saource such as sql server, oracle, or mongoDB.
/// </summary>
public class AccountConfig : EntityTypeConfiguration<Account>
{
public AccountConfig() : base()
{
this.ToTable("account", "dbo")
.HasKey(p => p.AccountID);
this.Property(p => p.AccountID)
.HasColumnName("account_id")
.HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
this.Property(p => p.Name)
.HasColumnName("name")
.HasColumnType("nvarchar")
.HasMaxLength(50)
.IsRequired();
//define the relationship between account and address
this.HasMany(p => p.Addresses).WithRequired().HasForeignKey(p => p.AccountID).WillCascadeOnDelete(false);
}
}
public class AddressConfig : EntityTypeConfiguration<Address>
{
public AddressConfig() : base()
{
this.ToTable("address", "dbo")
.HasKey(p => p.AddressID);
this.Property(p => p.AddressID)
.HasColumnName("address_id")
.HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
this.Property(p => p.AccountID)
.HasColumnName("account_id")
.IsRequired();
this.Property(p => p.FullAddress)
.HasColumnName("full_address")
.HasColumnType("nvarchar")
.HasMaxLength(256)
.IsRequired();
}
}
public class AccountDBContext : DbContext
{
public AccountDBContext() : this("accountDB") { }
public AccountDBContext(string nameOrConnectionString) : base(nameOrConnectionString)
{
//I dont want to use any database initialization i.e create database if it doesnt exist
//since your dev shop will have a deployment process, get use to the process of generating deployment scripts.
Database.SetInitializer<AccountDBContext>(null);
this.Configuration.ProxyCreationEnabled = false;
this.Configuration.LazyLoadingEnabled = false;
}
public IDbSet<Account> Accounts { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//map the domain types to the database tables using your database naming convention.
modelBuilder.Configurations.Add(new AddressConfig());
modelBuilder.Configurations.Add(new AccountConfig());
}
}
//repository is on the data access layer, because it's coupled to EF and the context object.
public class AccountRepository : IAccountRepository
{
private AccountDBContext _context;
public AccountRepository()
{
this._context = new AccountDBContext();
}
public AccountRepository(string nameOrConnectionString)
{
this._context = new AccountDBContext(nameOrConnectionString);
}
public IQueryable<Account> GetAccounts()
{
return this._context.Accounts
.AsNoTracking()
.Include("Addresses");
}
public void CreateAccount(Account account)
{
this._context.Entry(account).State = EntityState.Added;
this._context.SaveChanges();
}
public void UpdateAccount(Account account)
{
var temp = (from acc in this.GetAccounts()
where acc.AccountID == account.AccountID
select acc).First();
temp.Name = account.Name;
//sync address... we'll just add for brevity sake.
if (account.Addresses != null)
{
foreach (var addr in account.Addresses)
{
if (!addr.AddressID.HasValue)
{
this._context.Entry(addr).State = EntityState.Added;
}
}
}
this._context.SaveChanges();
}
}
public class Program
{
public static void Main()
{
try
{
IAccountService service = new AccountService(new AccountRepository());
//create new
var account = new Account()
{
Name = "john doe"
};
account.Addresses.Add(new Address()
{
FullAddress = "San Fran, CA"
});
account.Addresses.Add(new Address()
{
FullAddress = "Texas"
});
service.SaveAccount(account);
//get the account. I know the first accountID is one. I checked the database for testing.
;
var savedAccount = service.GetAccount(1);
//lets update it
savedAccount.Name = "J. Doe";
savedAccount.Addresses.Add(new Address()
{
AccountID = savedAccount.AccountID.Value,
FullAddress = "Conn"
});
service.SaveAccount(savedAccount);
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
}
}
你真的需要阅读实体框架。我们甚至没有谈论交易，并发，复杂对象图和模式等主题。