【ABP】项目示例（8）——数据迁移
数据迁移
在上一章节中，已经展示了数据播种的用途之一，即单元测试中进行数据初始化，在这一章节中，实现数据播种的另一重要用途，即数据迁移
该项目使用的是代码优先的开发模式，需要将领域模型迁移到数据库中的数据模型
EF数据迁移
在程序包管理控制台选中General.Backend.EntityFrameworkCore，执行以下命令安装EF数据迁移相关的Nuget包
Install-Package Microsoft.EntityFrameworkCore.Design -v 8.0.4
Install-Package Microsoft.EntityFrameworkCore.Tools -v 8.0.4
数据迁移需要一个单独的启动项目来进行运行，创建名称为General.Backend.DbMigrator的控制台项目
General.Backend.DbMigrator添加项目引用General.Backend.EntityFrameworkCore
新建名称为appsettings.json的默认加载配置文件，配置MySql数据库连接信息，并将文件属性设置为始终复制到输出目录
{
"ConnectionStrings": {
"Default": "server=localhost;database=general;user=youruser;password=yourpassword;port=yourport;CharSet=utf8mb4;Allow User Variables=True;SslMode=none;AllowLoadLocalInfile=true;"
}
}
在名称为General.Backend.EntityFrameworkCore的类库中，新建名称为GeneralDbContextFactory的数据迁移配置类，指定数据迁移的数据库连接信息和迁移类库
public class GeneralDbContextFactory : IDesignTimeDbContextFactory<GeneralDbContext>
{
public GeneralDbContext CreateDbContext(string[] args)
{
var configuration = BuildConfiguration();
var builder = new DbContextOptionsBuilder<GeneralDbContext>()
.UseMySql(
connectionString: configuration.GetConnectionString("Default"),
serverVersion: MySqlServerVersion.LatestSupportedServerVersion,
mySqlOptionsAction: optionsBuilder => optionsBuilder.MigrationsAssembly(Assembly.GetExecutingAssembly().FullName
));
return new GeneralDbContext(builder.Options);
}
private static IConfigurationRoot BuildConfiguration()
{
var builder = new ConfigurationBuilder()
.SetBasePath(Path.Combine(Directory.GetCurrentDirectory(), "../General.Backend.DbMigrator/"))
.AddJsonFile("appsettings.json", optional: false);
return builder.Build();
}
}
接下来进行数据迁移，选中General.Backend.DbMigrator作为启动项目，在程序包管理控制台选中General.Backend.EntityFrameworkCore，执行以下命令
Add-Migration Init
Update-Database
从图中可以看出已经成功进行了数据迁移，将领域模型映射到数据库中的表结构，生成对应的表
但是系统运行所依赖的初始数据并没有生成，这时就需要在数据迁移的过程中进行数据播种
ABP数据迁移
在名称为General.Backend.Domain的类库中的DataSeed文件夹下，新建名称为IGeneralDbSchemaMigrator的接口
public interface IGeneralDbSchemaMigrator
{
public Task MigrateAsync();
}
在名称为General.Backend.EntityFrameworkCore的类库中，新建名称为GeneralDbSchemaMigrator的迁移类，实现数据库迁移
public class GeneralDbSchemaMigrator : IGeneralDbSchemaMigrator, ITransientDependency
{
private readonly IServiceProvider _serviceProvider;
public GeneralDbSchemaMigrator(IServiceProvider serviceProvider)
{
_serviceProvider = serviceProvider;
}
public async Task MigrateAsync()
{
await _serviceProvider
.GetRequiredService<GeneralDbContext>()
.Database
.MigrateAsync();
}
}
在名称为General.Backend.Domain的类库中的DataSeed文件夹下，新建名称为GeneralDbMigrationService的迁移服务类，所有实现了IGeneralDbSchemaMigrator接口的迁移类都将进行数据库迁移，然后进行数据播种
public class GeneralDbMigrationService : ITransientDependency
{
private readonly IDataSeeder _dataSeeder;
private readonly IEnumerable<IGeneralDbSchemaMigrator> _generalDbSchemaMigrators;
public GeneralDbMigrationService(
IDataSeeder dataSeeder,
IEnumerable<IGeneralDbSchemaMigrator> generalDbSchemaMigrators)
{
_dataSeeder = dataSeeder;
_generalDbSchemaMigrators = generalDbSchemaMigrators;
}
public async Task MigrateAsync()
{
var initialMigrationAdded = AddInitialMigrationIfNotExist();
if (initialMigrationAdded)
{
return;
}
foreach (var migrator in _generalDbSchemaMigrators)
{
await migrator.MigrateAsync();
}
await _dataSeeder.SeedAsync();
}
private static bool AddInitialMigrationIfNotExist()
{
try
{
if (!DbMigrationsProjectExists())
{
return false;
}
}
catch (Exception)
{
return false;
}
try
{
if (!MigrationsFolderExists())
{
AddInitialMigration();
return true;
}
else
{
return false;
}
}
catch (Exception)
{
return false;
}
}
private static bool DbMigrationsProjectExists()
{
var dbMigrationsProjectFolder = GetEntityFrameworkCoreProjectFolderPath();
return dbMigrationsProjectFolder != null;
}
private static bool MigrationsFolderExists()
{
var dbMigrationsProjectFolder = GetEntityFrameworkCoreProjectFolderPath();
return dbMigrationsProjectFolder != null && Directory.Exists(Path.Combine(dbMigrationsProjectFolder, "Migrations"));
}
private static void AddInitialMigration()
{
string argumentPrefix;
string fileName;
if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX) || RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
{
argumentPrefix = "-c";
fileName = "/bin/bash";
}
else
{
argumentPrefix = "/C";
fileName = "cmd.exe";
}
var procStartInfo = new ProcessStartInfo(fileName,
$"{argumentPrefix} \"abp create-migration-and-run-migrator \"{GetEntityFrameworkCoreProjectFolderPath()}\"\""
);
try
{
Process.Start(procStartInfo);
}
catch (Exception)
{
throw new Exception("无法运行ABP命令行");
}
}
private static string? GetEntityFrameworkCoreProjectFolderPath()
{
var slnDirectoryPath = GetSolutionDirectoryPath();
return slnDirectoryPath == null
? throw new Exception("未找到解决方案文件夹")
: Directory.GetDirectories(slnDirectoryPath).FirstOrDefault(d => d.EndsWith(".EntityFrameworkCore"));
}
private static string? GetSolutionDirectoryPath()
{
var currentDirectory = new DirectoryInfo(AppContext.BaseDirectory);
while (currentDirectory != null && Directory.GetParent(currentDirectory.FullName) != null)
{
currentDirectory = Directory.GetParent(currentDirectory.FullName);
if (currentDirectory != null && Directory.GetFiles(currentDirectory.FullName).FirstOrDefault(f => f.EndsWith(".sln")) != null)
{
return currentDirectory.FullName;
}
}
return null;
}
}
在程序包管理控制台选中General.Backend.DbMigrator，执行以下命令安装ABP依赖注入和托管主机相关的Nuget包
Install-Package Volo.Abp.Autofac -v 8.3.0
Install-Package Microsoft.Extensions.Hosting -v 8.0.0
在名称为General.Backend.DbMigrator的类库中，新建名称为GeneralDbMigratorModule 的迁移模块类
[DependsOn(
typeof(AbpAutofacModule),
typeof(GeneralDomainModule),
typeof(GeneralEntityFrameworkCoreModule))]
public class GeneralDbMigratorModule : AbpModule
{
}
接下来新建名称为DbMigratorHostedService的托管服务类，迁移程序启动时，调用迁移服务类中的MigrateAsync方法，进行数据迁移和数据播种
public class DbMigratorHostedService : IHostedService
{
private readonly IHostApplicationLifetime _hostApplicationLifetime;
private readonly IConfiguration _configuration;
public DbMigratorHostedService(
IHostApplicationLifetime hostApplicationLifetime,
IConfiguration configuration)
{
_hostApplicationLifetime = hostApplicationLifetime;
_configuration = configuration;
}
public async Task StartAsync(CancellationToken cancellationToken)
{
using (var application = await AbpApplicationFactory.CreateAsync<GeneralDbMigratorModule>(options =>
{
options.Services.ReplaceConfiguration(_configuration);
options.UseAutofac();
}))
{
await application.InitializeAsync();
await application
.ServiceProvider
.GetRequiredService<GeneralDbMigrationService>()
.MigrateAsync();
await application.ShutdownAsync();
_hostApplicationLifetime.StopApplication();
}
}
public Task StopAsync(CancellationToken cancellationToken)
{
return Task.CompletedTask;
}
}
修改General.Backend.DbMigrator项目中的启动类Program，添加托管服务类到主机服务中
internal class Program
{
static async Task Main(string[] args)
{
await CreateHostBuilder(args).RunConsoleAsync();
}
public static IHostBuilder CreateHostBuilder(string[] args)
{
var hostBuilder = Host.CreateDefaultBuilder(args)
.ConfigureServices((hostContext, services) =>
{
services.AddHostedService<DbMigratorHostedService>();
});
return hostBuilder;
}
}
最后验证数据迁移和数据播种功能，将启动项目设置为General.Backend.DbMigrator，点击运行
输出如下信息，表明数据迁移成功
查询数据库的user和role表，可以看到已经存在了一个管理员用户和管理员角色，表明数据播种成功
解决方案的目录结构现如下
在下一章节中，实现表现层
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