entity-framework-4.1

问题 Given the following connection string: <add name="PrimaryDBConnectionString" connectionString="metadata=res://*/;provider=System.Data.SqlClient;provider connection string="Data Source=10.1.1.101;Initial Catalog=primary;Persist Security Info=True;User ID=myuserid;Password=mypassword;MultipleActiveResultSets=True;Application Name=EntityFramework"" /> I attempt to open a connection in my DAL with the following: using (PrimaryDBContext ctx = new PrimaryDBContext(ConfigurationManager

问题 I have a class that inherits a base class to which another class has relationships. Example: Base class: Animal Subclass 1: Dog Subclass 2: Cat Related one-to-many table: Vaccinations A dog can have multiple vaccinations. This is implemented as a List<Vaccination>. A cat can have multiple vaccinations. A vaccination record can only have one animal associated with it. A vaccination doesn't know if it's associated with a dog or a cat. (Dogs and cats use non-colliding GUIDs.) There is no Animal

问题 I have a class that inherits a base class to which another class has relationships. Example: Base class: Animal Subclass 1: Dog Subclass 2: Cat Related one-to-many table: Vaccinations A dog can have multiple vaccinations. This is implemented as a List<Vaccination>. A cat can have multiple vaccinations. A vaccination record can only have one animal associated with it. A vaccination doesn't know if it's associated with a dog or a cat. (Dogs and cats use non-colliding GUIDs.) There is no Animal

问题 I was watching some videos and tutorials for EF 4.1, and I do not understand any benefit of CodeFirst (except some if DB is very small 3-4 tables and I am lazy for creating DB first). Mostly, the best approach so far is to create Database in some sort of Database editor, which is sure faster then editing in the Entity Model and EF picks up every relationships and creates associations correctly. I know there are challenges in naming convention etc, but I feel its very confusing to manage Code

问题 I've just been talking with a colleague about Entity Framework change tracking. We eventually figured out that my context interface should have IDBSet<MyPoco> MyThings { get; } rather than IQueryable<MyPoco> MyThings { get; } and that my POCO should also have all it's properties as virtual . Using the debugger we could then see the tracking objects and also that the results contained proxies to my actual POCOs. If I don't have my POCO properties as virtual and have my context interface using

问题 I've just been talking with a colleague about Entity Framework change tracking. We eventually figured out that my context interface should have IDBSet<MyPoco> MyThings { get; } rather than IQueryable<MyPoco> MyThings { get; } and that my POCO should also have all it's properties as virtual . Using the debugger we could then see the tracking objects and also that the results contained proxies to my actual POCOs. If I don't have my POCO properties as virtual and have my context interface using

问题 I've just been talking with a colleague about Entity Framework change tracking. We eventually figured out that my context interface should have IDBSet<MyPoco> MyThings { get; } rather than IQueryable<MyPoco> MyThings { get; } and that my POCO should also have all it's properties as virtual . Using the debugger we could then see the tracking objects and also that the results contained proxies to my actual POCOs. If I don't have my POCO properties as virtual and have my context interface using

问题 Following this case, i'm trying to map a table column IsActive to two different entity property. is there any way to do this? 回答1: It is not possible. Each column must be mapped only once because otherwise it would lead to inconsistencies. For example if you would set different value to each property which one should be saved? Also having two properties exposing same field doesn't make sense. 回答2: You can't have two properties in the same Entity mapped to the same column. But there are

问题 Following this case, i'm trying to map a table column IsActive to two different entity property. is there any way to do this? 回答1: It is not possible. Each column must be mapped only once because otherwise it would lead to inconsistencies. For example if you would set different value to each property which one should be saved? Also having two properties exposing same field doesn't make sense. 回答2: You can't have two properties in the same Entity mapped to the same column. But there are

来源： https://stackoverflow.com/questions/11040926/sort-linq-query-by-child-collections-child-property