在实体框架中表示连接表 [英] Representing a Junction Table in Entity Framework

问题描述

我正在创建一种适用于以下逻辑的架构:

I am creating a schema where the following logic applies:

• 字符串可以属于多个位置.
• 多个位置可以具有多个 String ，或者没有 String .
• 必须记录形成 Location 和 String 之间的关系的 DateTime (作为 DateScraped )

• A String can belong to multiple locations.
• Multiple Locations can have multiple String, or no String.
• The DateTime (As DateScraped) at which the relationship between Location and String was formed must be recorded.

基本上，我已使用连接表将关系映射为多对多关系:

Basically, I've mapped the relationship as a many-to-many relationship using a junction table like so:

在映射Code First EF6中的图表(使用SQLite)时，我具有以下对象:

In mapping the chart in Code First EF6 (Using SQLite), I have the following objects:

public class Location
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long LocationId { get; set; }

    [Required]
    public string Country { get; set; }

    [Required]
    public string CityOrProvince { get; set; }

    [Required]
    public string PlaceOrCity { get; set; }

    [Required]
    public string PostalCode { get; set; }
}

public class String
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public long StringId { get; set; }

    [Required]
    public string SearchString { get; set; }
}

public class LocationStringMapping
{
    [Required]
    public string LocationId { get; set; }

    [Required]
    public string StringId { get; set; }

    [Required]
    public DateTime DateScraped { get; set; }
}

我到目前为止所做的一切都是基于推测，因为我似乎无法找到有关如何建立这样的关系的任何具体信息.通常，我会使用联结表，但这是在原始SQL中使用的.EF中的实现不同吗?

I've based what I've done so far on conjecture as I cannot seem to find any concrete information on how a relationship such as this must be built. Normally I'd use a junction table, but that is in vanilla SQL. Is the implementation different in EF?

我是否必须手动管理 LocationStringMapping 表，还是我不知道某种隐式关系模型?

Am I going to have to cumbersomely manage the LocationStringMapping table by hand or is there some kind of implicit relationship model I don't know about?

推荐答案

public class Location
{
    public long LocationId {get;set;}
    public virtual ICollection<LocationStringMapping> LocationStringMappings {get;set;}
    //other
}

public class String
{
    public long StringId {get;set;}
    public virtual ICollection<LocationStringMapping> LocationStringMappings {get;set;}
    //other
}

public class LocationStringMapping
{
    [Key, Column(Order = 0)]
    public long LocationId { get; set; }
    [Key, Column(Order = 1)]
    public long StringId { get; set; }

    public virtual Location Location {get;set;}
    public virtual String String {get;set;}

    public DateTime DateScraped {get;set;}
}

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