通过导航属性识别的关系,用HasOne or HasMany标识需要配置的导航属性,然后通过WithOne or WithMany继续链接来配置逆向导航属性 One-to-One Relationship 1:1的关系在两个关联实体中分别都有一个关联导航属性,但是在依赖实体中必须显式有一个外键属性来标识,另一个则是主体实体 Many-To-Many Relationship 多对多的...
Foreign key: 外键 Navigation property: 导航属性,出现在父实体或主实体中,用来维系两个实体间的关系。 Collection navigation property:集合导航,是一个ICollection<T> Reference navigation property:引用导航,是一个T Inverse navigation property:反向导航属性 Self-referencing relationship:自引用的关系,如树形结构中的...
'System.Data.Entity.ModelConfiguration.ModelValidationException' occurred in EntityFramework.dll EntityType 'Standard' has no key defined. Define the key for this EntityType. 如果你非要定义StdId作为主键,那你必须使用DataAnnotations或者Fluent API去配置它成为主键,我们将在后面的章节学习到。 关系(Relationshi...
Last MarchAlex Jamesposted to our design blog aboutour plans for adding foreign keys to the entity framework. Since then we’ve pushed forward with implementing FK associations and properties and have included them inVisual Studio 2010 Beta 2. This article offers a walkthrough of foreign key ...
Foreign Key Association - 外部索引鍵關聯實體間的關聯,透過外部索引鍵屬性加以管理。 Identifying Relationship - 識別關聯性一種關聯性,其中主要實體的主索引鍵也是相依實體之主索引鍵的一部分。 在這種關聯性中,如果沒有主要實體,相依實體就無法存在。
Foreign Key Association - 外部索引鍵關聯 實體間的關聯,透過外部索引鍵屬性加以管理。 如需詳細資訊,請參閱定義及管理關聯性。 Identifying Relationship - 識別關聯性 一種關聯性,其中主要實體的主索引鍵也是相依實體之主索引鍵的一部分。 在這種關聯性中,如果沒有主要實體,相依實體就無法存在。 如需詳細資訊,請...
在Entity Framework 中 SaveChanges 时,出现下面的错误,请问如何解决? The operation failed: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. When a change is made to a relationship, the related foreign-key property is set to a null value....
Currently, I've been trying to figure out how to have the current entity framework completely ignore foreign key associations. Anybody know if this is possible? Thanks, Paul Anonymous June 19, 2009 What are Stub Entities? A stub entity is a partially populated entity that stands in for the ...
Framework 預設會實作開放式並行存取 (Optimistic Concurrency) 模型。如需詳細資訊，請參閱儲存變更及管理並行存取 (Entity Framework)12。參考某些關聯的非對稱性質。方向在結構描述內是與 NavigationProperty 或 页码，1/7 2011-02-17 http://msdn.microsoft.com/zh-tw/library/bb387161(d=printer).aspx ...
Entity Framework Core3.0, 3.1 HasForeignKey(IReadOnlyList<String>, Boolean) 将属性配置为用作此关系的外键。 C# publicMicrosoft.EntityFrameworkCore.Metadata.Builders.IConventionRelationshipBuilderHasForeignKey(System.Collections.Generic.IReadOnlyList<string> propertyNames,boolfromDataAnno...