时间：2021-07-01 10:21:17 帮助过：13人阅读
语言资源(LocaleStringResource):
1 public partial class LocaleStringResource : BaseEntity<int> 2 { 3 /// <summary> 4 /// Gets or sets the language identifier 5 /// </summary> 6 public int LanguageId { get; set; } 7 8 /// <summary> 9 /// Gets or sets the resource name 10 /// </summary> 11 public string ResourceName { get; set; } 12 13 /// <summary> 14 /// Gets or sets the resource value 15 /// </summary> 16 public string ResourceValue { get; set; } 17 18 /// <summary> 19 /// Gets or sets a value indicating whether this resource was installed by a plugin 20 /// </summary> 21 public bool? IsFromPlugin { get; set; } 22 23 /// <summary> 24 /// Gets or sets a value indicating whether this resource was modified by the user 25 /// </summary> 26 public bool? IsTouched { get; set; } 27 28 /// <summary> 29 /// Gets or sets the language 30 /// </summary> 31 public virtual Language Language { get; set; } 32 33 }View Code
其中语言及资源主外键关系配置如下
1 public partial class LanguageMapper : IEntityTypeConfiguration<Language> 2 { 3 public void Configure(EntityTypeBuilder<Language> builder) 4 { 5 builder.ToTable("Language"); 6 builder.HasKey(r => r.Id); 7 builder.HasIndex(r => r.LanguageCulture); 8 builder.HasIndex(r => r.Name); 9 builder.HasIndex(r => r.UniqueSeoCode); 10 } 11 }View Code
public partial class LocaleStringResourceMapper : IEntityTypeConfiguration<LocaleStringResource> { public void Configure(EntityTypeBuilder<LocaleStringResource> builder) { builder.ToTable("LocaleStringResource"); builder.HasKey(r => r.Id); builder.HasIndex(r => r.LanguageId); builder.HasIndex(r => r.ResourceName); builder.HasOne(r => r.Language).WithMany(b => b.LocaleStringResources) .HasForeignKey(fk => fk.LanguageId); } }
2、父子关系 ：
1 public class TechCategory:BaseEntity<int> 2 { 3 /// <summary> 4 /// 名称 5 /// </summary> 6 public string Name { get; set; } 7 /// <summary> 8 /// 分类描述 9 /// </summary> 10 public string Descript { get; set; } 11 /// <summary> 12 /// meta标题 13 /// </summary> 14 public string MetaTitle { get; set; } 15 /// <summary> 16 /// meta描述 17 /// </summary> 18 public string MetaDescript { get; set; } 19 /// <summary> 20 /// 缩略图 21 /// </summary> 22 public string Thumb { get; set; } 23 /// <summary> 24 /// 图片 25 /// </summary> 26 public string Image { get; set; } 27 /// <summary> 28 /// 排序 29 /// </summary> 30 public int Sort { get; set; } 31 /// <summary> 32 /// 父级分类 33 /// </summary> 34 public int? ParentId { get; set; } 35 36 /// <summary> 37 /// 父级分类 38 /// </summary> 39 40 public virtual TechCategory Parent { get; set; } 41 public virtual ICollection<Technology> Technologys { get; set; } 42 /// <summary> 43 /// 子级 44 /// </summary> 45 public virtual ICollection<TechCategory> Childs { get; set; } 46 /// <summary> 47 /// 关键词 48 /// </summary> 49 public string Slug { get; set; } 50 /// <summary> 51 /// 创建时间 52 /// </summary> 53 public long CreatedOn { get; set; } 54 }View Code
1 public class TechCategoryMapper : IEntityTypeConfiguration<TechCategory> 2 { 3 public void Configure(EntityTypeBuilder<TechCategory> builder) 4 { 5 builder.ToTable("TechCategory"); 6 builder.HasKey(r => r.Id); 7 builder.HasMany(r => r.Childs).WithOne(x => x.Parent) 8 .HasForeignKey(fk => fk.ParentId); 9 builder.HasIndex(r => r.Name); 10 } 11 }View Code
二、数据库上下文:
根据前面创建的相关实体类 以及相关mapper类型，我们可以重现DbContext的OnModelCreating的方法,反射出实现了IEntityTypeConfiguration接口的相关mapper类型创建相关实体-数据表的相关对应关系
1 public class DefaultContext : DbContext 2 { 3 public DefaultContext(DbContextOptions<DefaultContext> opt) 4 :base(opt) 5 { 6 AutoCommitEnabled = true; 7 } 8 protected override void OnModelCreating(ModelBuilder builder) 9 { 10 base.OnModelCreating(builder); 11 var mappingInterface = typeof(IEntityTypeConfiguration<>); 12 // Types that do entity mapping 13 var mappingTypes = GetType().GetTypeInfo().Assembly.GetTypes() 14 .Where(x => x.GetInterfaces().Any(y => y.GetTypeInfo().IsGenericType && y.GetGenericTypeDefinition() == mappingInterface)); 15 16 // Get the generic Entity method of the ModelBuilder type 17 var entityMethod = typeof(ModelBuilder).GetMethods() 18 .Single(x => x.Name == "Entity" && 19 x.IsGenericMethod && 20 x.ReturnType.Name == "EntityTypeBuilder`1"); 21 22 foreach (var mappingType in mappingTypes) 23 { 24 25 // Get the type of entity to be mapped 26 var genericTypeArg = mappingType.GetInterfaces().Single().GenericTypeArguments.Single(); 27 28 // Get the method builder.Entity<TEntity> 29 var genericEntityMethod = entityMethod.MakeGenericMethod(genericTypeArg); 30 31 // Invoke builder.Entity<TEntity> to get a builder for the entity to be mapped 32 var entityBuilder = genericEntityMethod.Invoke(builder, null); 33 34 // Create the mapping type and do the mapping 35 var mapper = Activator.CreateInstance(mappingType); 36 mapper.GetType().GetMethod("Configure").Invoke(mapper, new[] { entityBuilder }); 37 } 38 foreach (var relationship in builder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys())) 39 { 40 relationship.DeleteBehavior = DeleteBehavior.Restrict; 41 } 42 } 43 }View Code
三、多数据库支持:
多数据库的支持，并不是意味着同时对多种数据库操作，当然，后面，我们会尝试同时对多种数据库操作，这可能需要多个上下文，暂且不论。分布式数据库。我们的项目可能是在windows上开发的使用的是SqlServer，我们要发布到linux上，SqlServer 2017 据说是支持liunx的，但是还没出... 当然不是说 SqlServer 就不能装在liunx上，但是我们的Liunx服务器可能已经安装了MySql或 Oracle，我们希望使用现有的，又或者是，我们需要切换数据库。那么，我们需要可以随时切换数据库的支持，以上篇的mysql为例：
1.引用相关包，mysql我用的Pomelo.EntityFrameworkCore.MySql，国人开发的mysql for ef core的相关服务对象,ef
core 2.0中需要指定2.0版本(Install-Package Pomelo.EntityFrameworkCore.MySql -Version 2.0.0-rtm-10059),
2.需改配置文件依据相关配置动态加载数据库提供对象；相关代码及配置如下
nuget引用列表
1 <ItemGroup> 2 <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.0.0" /> 3 <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="2.0.0" /> 4 <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="2.0.0" /> 5 <PackageReference Include="Pomelo.EntityFrameworkCore.MySql" Version="2.0.0-rtm-10058" /> 6 </ItemGroup>View Code
相关配置文件修改
"ConnectionStrings": { "MongoDbConnectionString": "mongodb://tchistory:tc123456@127.0.0.1/history", "ConnectionString": "Data Source=127.0.0.1;Initial Catalog=farmdata;User ID=root;Password=123456", "DataProvider": "MySql" },
在startup.cs 的configureServices方法中添加数据库上下文
public void ConfigureServices(IServiceCollection services) { services.AddDbContext<DefaultContext>(option => option.UseFarmDatabase(Configuration)); services.UseFarmService(Configuration); services.AddMvc(); }
数据库提供对象扩展方法如下:
public static DbContextOptionsBuilder UseFarmDatabase(this DbContextOptionsBuilder optionsBuilder, IConfiguration configuration)
{
string provider = configuration.GetConnectionString("DataProvider"), connection = configuration.GetConnectionString("ConnectionString");
if (provider.Equals(DataBaseServer.SqlServer, StringComparison.InvariantCultureIgnoreCase))
{
return optionsBuilder.UseSqlServer(connection);
}
else if (provider.Equals(DataBaseServer.MySql, StringComparison.InvariantCultureIgnoreCase))
{
return optionsBuilder.UseMySql(connection);
}
else
{
throw Error.Argument("UseDatabaseServer", "No databaseProvider");
}
}
在程序包管理控制台添加相关迁移 命令 add-migration init: 会在当前目录下生成相关迁移目录
执行update-database -Verbose提交更改到数据库,这样数据库迁移及更改就算完成了,其中要注意的地方是ef core 2.0 中有些数据库提供对象暂时是没有完全实现，如用Pomelo.EntityFrameworkCore.MySql -Version 1.1.2 可能会报方法未实现，更新2.0 rtm版本即可。
祝愿你在码农道路上越走越顺畅;
一起学ASP.NET Core 2.0学习笔记(二): ef core2.0 及mysql provider 、Fluent API相关配置及迁移
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