将数组映射到单行
我有以下课程：
public class InventoryItem
{
private Usage[] usages = new Usage[12];
virtual public Usage[] Usages { get { return usages; }}
virtual public string Name{get;set;}
}
public class Usage
{
virtual public double Quantity{get;set;}
virtual public string SomethingElse{get;set;}
}
我知道Usages.Length将始终是12。我认为这是最好的 像这样将其存储在数据库中：
Name nvarchar(64),
Usage_Quantity_0 float,
Usage_SomethingElse_0 nvarchar(16),
Usage_Quantity_1 float,
Usage_SomethingElse_1 nvarchar(16),
...
Usage_Quantity_11 float,
Usage_SomethingElse_11 nvarchar(16),
我怎样才能完成这个工作？
I have the following classes:
public class InventoryItem
{
private Usage[] usages = new Usage[12];
virtual public Usage[] Usages { get { return usages; }}
virtual public string Name{get;set;}
}
public class Usage
{
virtual public double Quantity{get;set;}
virtual public string SomethingElse{get;set;}
}
I know that Usages.Length will always be 12. I think it would be best
to store it in the DB like so:
Name nvarchar(64),
Usage_Quantity_0 float,
Usage_SomethingElse_0 nvarchar(16),
Usage_Quantity_1 float,
Usage_SomethingElse_1 nvarchar(16),
...
Usage_Quantity_11 float,
Usage_SomethingElse_11 nvarchar(16),
How can I get this done?
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一个在数组和 12 个私有字段之间进行转换的 getter/setter 怎么样？在Hibernate中（我不知道NHibernate），映射可以放在字段上，你可以使用 可嵌入实体，将
Usage映射到InventoryItem中的2列。如果可嵌入实体在 NHibernate 中不可用，那么您将需要 24 个字段。即使存在固定基数，一对多关系可能仍然更可取。如果担心性能，可以搜索一下N+1问题和eager fetching。
What about a getter/setter that converts to/from an array and 12 private fields? In Hibernate (I don't know about NHibernate), the mapping can be placed on the field and you can use embeddable entities to have
Usagebe mapped to 2 columns inInventoryItem. If embeddable entities are not available in NHibernate, then you will need 24 fields.A 1-to-many relationship is maybe still preferable even if there is a fixed cardinality. If you are worried about performance, search for the N+1 problem and eager fetching.