代理查询

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代理查询（Agent Query）属于动态查询的特殊构建方式。

它可以将特定实体（Entity）的每个属性映射为对数据行（Row）的访问，可用于对 Key-Value 存储结构的便捷访问。

示例

定义 Key-Value 表实体 AppRegistryEntity：

public class AppRegistryEntity : KeyValueEntity { }

public class ApplicationDbContext : DbContext
{
    public DbSet<AppRegistryEntity> AppRegistries { get; set; }
}

定义代理实体 AppRegistry：

public class AppRegistry : KeyValueAgent<AppRegistryEntity>
{
    public virtual string Theme { get; set; } = "Default";
    public virtual string Color { get; set; }
 
    public virtual int Volume { get; set; }
    public virtual DateTime? LoginTime { get; set; }
 
    public virtual bool Lock { get; set; }
}

查询操作

using (var context = ApplicationDbContext.UseMySql())
using (var query = context.BeginAgentQuery(x => x.AppRegistries))
{
    var jerry = query.GetAgent<AppRegistry>("/User/Jerry");
    
    jerry.Theme = "Sky";
    jerry.Color = "brown";
    jerry.Volume = 10;
    jerry.LoginTime = now;
    jerry.Lock = true;
 
    context.SaveChanges();
}

执行结果

Id	Item	Key	Value
<Guid>	/User/Jerry	Theme	Sky
<Guid>	/User/Jerry	Color	brown
<Guid>	/User/Jerry	Volume	10
<Guid>	/User/Jerry	LoginTime	2023/1/1 15:00:00
<Guid>	/User/Jerry	Lock	True

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