Develop Reference

Entity Framework 6 specific column mapping

In SQL, I would tell the database what the foreign key constraint is.
But fluent EF6 apparently does not have a way for me to specify what column to use when binding collections.
Is it not possible to tell DbModelBuilder exactly what column to bind relationships on? Or does it demand to be the primary key at all times?
Table_Person
id int // pkey. Multiple people records
UniqueID int // the unique person
sometext varchar(256) // database therefore tracks changes to this, since unique person can have many records (pkeys).
Table_Address
id int //pkey
fk_unique int // should map to UniqueID of person, NOT the pkey.
line1 varchar(512)
state varchar(64)
etc
One unique person has many records, and their uniqueID (not pkey) has many associated addresses. Actual structure is far more complex than that. But am looking for a way to do this fundamentally...
Would very much so like to have an ICollection<Address> Addresses within the Persons model. But to enable such a thing for code-first migrations... seems impossible?
Yes I could Add-Migration and then modify the generated code/sql manually. But doesn't that defeat the point? Or is that common practice?

If you're able to modify the DB schema you could put UniqueIDs for people into their own table named "Person" and rename the existing table to "PersonVersion". Then have FKs to the new "Person" table on "PersonVersion" and "Address". And finally, create the Person, PersonVersion, and Address models in your app code and EF should bind without problem.

EF6 Table Splitting with foreign keys (Database first)

I'm currently investigating the possibility to use table splitting with EF to stop pulling too many columns for nothing. As for now, I'm able to create a new entity, cut/paste the fields into the sub-entity and map it without much problems.
However, if one of those fields is a FK in the master table, it gives me the following error
"Running transformation: There is no property with name 'IdDocumentImportSource' defined in type referred by Role 'DocumentImports'."
I do understand that the both tables have a NavigationProperties that cannot be resolved anymore by the association FK because the field has been moved to the child table.
Here's my question; Is there a way to automaticaly move the association FK to the child table? I could only make it work by manually deleting the association, both navigation properties, creation the association FK of the child. It involves quite a lot of work on my part if I have to do all this manually for every association FK I got...!
DocumentImports is the ParentTable that I splitted into a new child table DocumentImports_StatusDetail and DocumentImportSources is the table being referenced by the FK.
Thanks!

Code first of EF, how to define navigation property relationship without setting foreign key between table in database

I use code first of Entity framework. There are two classes "Question" and "User". I defined a relationship as below:
this.HasRequired(v => v.Creator).WithMany(v => v.Questiones)
.HasForeignKey(v => v.CreatorId).WillCascadeOnDelete(false);
After gernerating the database I found that it always create foreign key between Id of User and CreatorId of Question. Because of lower performance of FK(and other reason),I want to define navigation property relationship without setting foreign key in database? Delete FK after EF created it?
If cannot do this using fluent api, could you tell me why EF designed in this way please?
About the lower performance of FK. I have a User table with 5 Million records in it. when I insert a Question into db, since the db check the question.CreatorId validation from User table, it always slower than without FK.
And there are many other reasons that I need to remove FK.
I think I am somewhat obsession because I think that deleting FK after created it is strangely and ugly. What i want is implementing this by using something like WithoutForeignKey in fluent api:
this.HasRequired(v => v.Creator).WithMany(v => v.Questiones)
.WithoutForeignKey(v => v.CreatorId).WillCascadeOnDelete(false);

Without questioning why are you trying to do this strange thing and going just to the answer: you could delete fk constraint after generated, or you could use migrations and remove FK generation from the migration code.
SQL code generated when traversing nav properties will work even if fk constraint doesn't exist, except for cascade deleting

If you want a relationship between two tables, you need to define a foreign key. No way around it. Even if you use Map() in fluent api, you can only hide the foreign key in your model, in the background EF will still use it and it will exist in the database.
Also I don't get what you mean by "performance" of foreign key? One extra (likely small) column won't make a difference. If you mean the navigation properties for the performance part, you can do 3 things:
Don't include them in your model
Make them non-virtual to disable lazy loading
Disable lazy loading all together with ctx.Configuration.LazyLoadingEnabled = false;

If you don't want to tell db about relation and treat both entities as not related (I wonder why), then just ignore these navigation properties and FK field. Note that you will be responsible for managing related entities: saving and loading them from db, updating ids etc
this.Ignore(q => q.Creator);
this.Ignore(q => q.CreatorId);
And you also need to ignore other side of relation, otherwise EF will generate FK column with default name Creator_CreatorId. So in Creator entity configuration:
this.Ignore(c => c.Questiones);

Entity Framework 5 Enum Naming

I am using EF 5 with migrations and code first. It all works rather nicely, but there are some issues/questions I would like to resolve.
Let's start with a simple example. Lets say I have a User table and a user type table. The user type table is an enum/lookup table in my app. So the user table has a UserTypeId column and a foreign key ref etc to UserType. In my poco, I have a property called UserType which has the enum type.
To add the initial values to the UserType table (or add/change values later) and to create the table in the initial migrator etc. I need a UserType table poco to represent the actual table in the database and to use in the map files. I mapped the UserType property in the User poco to UserTypeId in the UserType poco. So now I have a poco for code first/migrations/context mapping etc and I have an enum. Can't have the same name for both, so do I have a poco called UserType and something else for the enum or have the poco for UserType be UserTypeTable or something?
More importantly however, am I missing some key element in how code first works? I tried the example above, ran Add-Migration and it does not add the lookup table for the enum.

If I understood properly your questions and what you're confused about,
Enums support has nothing to do with lookup tables on the Db side.
Enums are simply allowing you to have properties in your classes that are Enum-s and that is translated into 'int'-s basically - so there is nothing much else in there.
For more info you might wanna look at this video from Julie Lerman on Enum-s support
hope this helps

In my experience the enum is more important to your code than the lookup class so give it the proper name. I would also keep the look up class isolated without any relationship to the User in my Model. If it trully is only for lookup, then you don't need it hanging off of your User. Your enum with a DescriptionAttribute can fulfill the lookup in your code.
UserTypeLookup might be a good name since that sounds like what you will be using it for. Then you can use that class to maintain the table.
Assuming you don't map the relationship between UserTypeLookup and User in ef code first, the only thing you should need to create in the DB manually is the foriegn key relationship between the UserType column in your User table and the PK from the UserTypeLookup table. UserTypeLookup can still be an entity and EF should still generate the DB table for it even if you don't setup any relationships for it.

Problems with automatic property creation when manually mapping relationships between tables with no foreign keys in L2S

Pardon the massive headline.
I'm in the situation of having to build an application on top of a database, that I cannot make any changes to. The database does not have any primary- or foreignkeys set.
I'm using linq-2-sql, and I'm interested in having some properties exposed on the entities generated from my dbml. For instance, in the hypothetical example of a one-to-many relationship between table education and student - where each student record has a reference to an education id, I'd like to be able to go:
var student = GetAStudentFromContextOrWhatever();
var studentsEducation = student.Education;
It is my experience, that this kind of property is automatically generated when I drag'n'drop tables with foreignkey relationships from the server explorer.
However as previously mentioned, in this case I do not have these foreign key relationships - rather I am adding the relationships manually in the dbml file, specifying parent and child class.
When I add these relationships, I expect the involved entities in the designer.cs of my context to get populated with properties of a kind like those described above.
This, however, does not happen.
What must I do for my dbml to create these properties for me - based on these manually mapped associations between entities/tables that, on a database level, do not have foreign key associations?
Cheers!

L2S is just that Linq-to-SQL. If it isn't in SQL it won't be generated. The expression trees behind L2S just can't understand what you are doing. The place for your association is in a partial class file which you will have create manually. Also it probably won't update or insert through the association.

I know this is a very old question, but I just ran into the same problem. In order for the relationship in the DBML designer to automatically create the association properties for you, you need to have primary keys on your objects. If you click the column name in the designer, you'll see that your PK field has PrimaryKey = false. Switch that to True and build; all should be well.
Patrick