I think I have an error in my model, but I'm not sure what it is.
First the error
The INSERT statement conflicted with the FOREIGN KEY constraint
"FK_dbo.ProjectDocAccess_dbo.ProjectDoc_ProjectDocAccessID". The conflict
occurred in database "dbname",
table "dbo.ProjectDoc", column 'ProjectDocID'.
The ProjectDocAccess model (trimmed down)
public class ProjectDocAccess
{
public int ProjectDocAccessID { get; set; }
public int ProjectDocID { get; set; }
public virtual ProjectDoc ProjectDoc { get; set; }
}
The ProjectDoc model (trimmed down)
public class ProjectDoc
{
public int ProjectDocID { get; set; }
public int ProjectID { get; set; }
public ProjectDocAccess ProjectDocAccess { get; set; }
public Project Project { get; set; }
}
The fluent API mapping
modelBuilder.Entity<ProjectDocAccess>()
.HasRequired(p => p.ProjectDoc).WithOptional()
.WillCascadeOnDelete(true);
When I attempt to insert a new record in the ProjectDocAccess table, it forces me to insert a value in the ProjectDocAccessID field. In all of my other models, this auto increments. I'm not sure what I am doing wrong. Help?
UPDATE
Based on the answer I selected. This is what I did to fix it.
Removed the fluent API mapping altogether.
Updated the ProjectDocAccess model as follows
public class ProjectDocAccess
{
[Key, ForeignKey("ProjectDoc")]
public int ProjectDocAccessID { get; set; }
public virtual ProjectDoc ProjectDoc { get; set; }
}
First, when issues like this you should take a look at your migration files generated (or if you don't have them just enable it) - it shows in a 'higher level' form of tables/mappings generated for you.
Problem is that you have 'one to one' relationship and your ProjectDocAccess to ProjectDoc is mapped with pk -> pk. Code first automatically does that for you in these cases as that's the only supported way of making the one to one.
So your ProjectDocAccessID is at all times mapped == the same as your ProjectDocID.
The ProjectDocID is auto-generated - but you need to put the access-id to match it yourself. (I'm guessing that could be automated but strictly in db terms it's not).
So, it can't auto-generate things. It has to be copied from the principal
table, where the 'optional' is.
With your current entities it is what it is - but you could rearrange things maybe (though one-to-one are tough to make and could lead to issues if you don't get it right).
There is an option to create one to one using FK-s only (which would then allow you to place an 'independent' primary key on your 'access' table) - but requires manually injecting SQL CONSTRAINT - e.g. see this page - http://weblogs.asp.net/manavi/archive/2011/05/01/associations-in-ef-4-1-code-first-part-5-one-to-one-foreign-key-associations.aspx
If you want the ProjectDocAccessID to be generated by the database (an Identity column) then you should decorate that property with the DatabaseGenerated attribute, like this:
[DatabaseGenerated(DatabaseGenerationOption.Identity)]
public int ProjectDocAccessID { get; set; }
As Andrei pointed out, you may also need to decorate it with the [Key] attribute as well.
Source: http://msdn.microsoft.com/en-US/data/jj591583
Related
I am using EF6 but...
I can not change the database.
So, if I'm not wrong, I need to create a model that suits the database.
I have to models in relationship one to many:
[Table("ReceCli")]
public class ReceCli
{
[Key]
public int Indice { get; set; }
[Required, StringLength(12)]
[Display(Name = "Nº Documento")]
public string NDOC { get; set; }
[Display(Name = "Banco do boleto")]
[Column("CodBancoBoleto")]
public int CodBancoBoleto { get; set; }
public Banco Banco { get; set; }
}
and
[Table("Bancos")]
public class Banco
{
[Key]
public int CodBanco { get; set; }
[Column("Banco")]
[Required, StringLength(50)]
[Display(Name = "Banco")]
public string Nome { get; set; }
}
In the database this relations are expressing like:
ALTER TABLE [dbo].[ReceCli] WITH NOCHECK ADD CONSTRAINT [ReceCli_CodBancoBoleto] FOREIGN KEY([CodBancoBoleto])
REFERENCES [dbo].[Bancos] ([CodBanco])
GO
ALTER TABLE [dbo].[ReceCli] CHECK CONSTRAINT [ReceCli_CodBancoBoleto]
When executing return an error:
Invalid column name 'Banco_CodBanco'.
I can not change the database.
How can I change the model to EF use ReceCli_CodBancoBoleto name of column instead of Banco_CodBanco ?
You can do model an existing db by hand but you can also tell EF to generate the model from an existing database.
As for your example, a couple of things:
The relationship you have modeled is not one to many but one to one.
Public Banco Banco {get; set;}
Change To:
Public ICollection<Banco> Bancos {get;set;}
There are several ways you can model relationships with EF. Here's a sample of Modeling 1 to many relationships in EF.
The Column attribute is used to match to names in the DB. Make sure your EF CF properties that don't match the database have a Column Attribute. For Your RecCli it should look something like:
[Column("CodBanco")]
public int CodBancoBoleto { get; set; }
or
public int CodBanco { get; set; }
However, you are mapping a 1 to many relationship so having the CodBancoBoleto is not needed. Just use the navigation property of Public ICollection<Banco> Bancos {get;set;}. This should suffice except you might have to put a ForeignKey attribute for it telling it to use CodBanco as the key for the navigation.
[ForeignKey("CodBanco")]
Public ICollection<Banco> Bancos {get;set;}
You might have to do this for all your keys as the default code first convention for keys end with Id. I say might as your Banco Class's key is named properly CodBanco and marked with the Key. So you might be fine.
A final note is that you appear to be trying to use the constraints name for the mapping. You don't use the constraint name, rather the actual column names, aka the references part of the constraint.
I need to implement Entity-Attribute-Value functionality on multiple data tables using Entity Framework. Let's say I have an attribute value EF class that looks like this:
public class EntityAttributeValue
{
// Not important to my question.
public virtual Entity ParentEntity { get; set; }
public virtual EntityAttribute ParentEntityAttribute { get; set; }
// Field in question.
public Guid ParentSurrogateKey { get; set; }
public string Value { get; set; }
...
}
Then I have multiple entities that have supplementary EAV values associated with them:
public class Entity1
{
// Key. EntityAttributeBalue.ParentSurrogateKey maps to this.
[Key]
public Guid SurrogateKey { get; set; }
// Standard properties.
public string Property1 { get; set; }
public string Property2 { get; set; }
// Collection of EAV values associated with this entity/table.
[ForeignKey("ParentSurrogateKey")]
public virtual IList<EntityAttributeValue> EntityAttributeValues { get; set; }
}
public class Entity2
{
// Key. EntityAttributeBalue.ParentSurrogateKey maps to this.
[Key]
public Guid SurrogateKey { get; set; }
// Standard properties.
public string OtherProperty1 { get; set; }
public string OtherProperty2 { get; set; }
// Collection of EAV values associated with this entity/table.
[ForeignKey("ParentSurrogateKey")]
public virtual IList<EntityAttributeValue> EntityAttributeValues { get; set; }
}
My problem is that both Entity1 and Entity2 have EntityAttributeValue objects associated with them. Code first migrations tries to create a foreign key from EntityAttributeValue back to Entity1 and another one back to Entity2 on ParentSurrogateKey. The surrogate key for any single given EntityAttributeValue is only associated with either one Entity1 or one Entity2 (or, expanding out, one EntityN...), not both/all.
I have a many to many relationship here, but one side not only maps to multiple rows, but multiple entities/tables over a shared GUID column.
How should I be approaching this? Should I just remove the EntityAttributeValue foreign keys back to Entity1 and Entity2 from the automatic migration (which would be a long term pain)? Should I be manually retrieving the list of EntityAttributeValues for a given EAV entity instead of relying on EF to do it for me?
Well, the answer turned out to be obvious and simple. I needed to define a many-to-many relationship with FluentAPI. In OnModelCreating, I just added:
modelBuilder.Entity<Entity1>()
.HasMany(m => m.EntityAttributeValues)
.WithMany();
modelBuilder.Entity<Entity2>()
.HasMany(m => m.EntityAttributeValues)
.WithMany();
I thought I had tried this, but I guess I hadn't. Because the many-to-many relationship creates an intermediate table for each entity and the foreign keys are on that intermediate table (and there is only a row in the intermediate table when a given EntityAttributeValue applies to a given Entity), no foreign key issues.
Considering the documentation here, you can define foreign key relationships in your pocos like the given example:
public class Customer
{
[References(typeof(CustomerAddress))]
public int PrimaryAddressId { get; set; }
[Reference]
public CustomerAddress PrimaryAddress { get; set; }
}
However, let's say that my CustomerAddress poco class actually has to be defined like this because someone decided to design the table like this a long, long time ago.
public class CustomerAddress
{
[PrimaryKey]
public int Id_1 { get; set; }
[PrimaryKey]
public string Id_2 { get; set; }
}
How can I properly define my [Reference] for the PrimaryAddress property in the Customer class with the composite key defined in CustomerAddress?
You can't using APIs that rely on it (but you can still use SELECT)
Please see OrmLite limitations.
I had same problem with a legacy database I can't modify (because another project cohabit with mine).
So I deleted primary key then created a new Id field (autoincrement) on the database (PK) and finally created a unique constraint (NOT NULLABLE) on both fields.
So now, I can use OrmLite to select properly without breaking compatibility with the other project.
I have an issue with an Entity Framework from DB model.
My issue is down to the fact that one of my models has a multiple references to one table.
public partial class Customer
{
public int Id { get; set; }
public Nullable<int> PrimaryEngId { get; set; }
public Nullable<int> AssignedDevloperId { get; set; }
public virtual Engineer Engineer { get; set; }
public virtual Engineer Engineer1 { get; set; }
}
In my model the columns are mapped respectively, however when a colleague builds the model from the same database the two are reversed.
I believe the issue is that the first mapping to in was the primaryEngId
and the Db constraint is called FK_Customer_Engineer.
And the assigned developer id was added subsequently and the DB constraint is called FK_Customer_Devloper
So alphabetically Developer come before Engineer and Entity Framework now maps them the other way round.
My code references the Engineer in quite a lot of places which now won't work
Is there any way out of this?
Many thanks
Ian
You have to add missing ForeignKey attributes on foreign keys for those two navigation properties:
[ForeignKey("Primary")]
public int? PrimaryEngId { get; set; }
[ForeignKey("Assigned")]
public int? AssignedDevloperId { get; set; }
public virtual Engineer Primary { get; set; }
public virtual Engineer Assigned { get; set; }
NOTE: Also don't use generic names for navigation properties with EF. In the nutshell one of the best things EF gives you is that you can say:
#myCustomer.Assigned.Name
etc in the view, and you are totally screwing it up with names like Engineer and Engineer1.
NOTE2: Keep Nullable<int> to code generation. int? is a lot more readable.
NOTE3: Use VS refactoring to rename properties Engineer and Engineer1 to what they should be ( PrimaryEngineer and AssignedEningeer etc). After that add ForeignKey attributes to your model. That should be enough. However, any future changes that you are doing has to be done in the Code and not in db.
IF on the other hand you are constantly regenerating entities and context code from database, make sure that all your foreign keys has meaningful names, as EF will use them to generate name.(ie it is not named Engineer1 out of blue) Rename those foreign keys to reflect what logical relationship is. Ie you most likely have the following foreign keys in db:
FK_Customer_Engineer
FK_Customer_Engineer1
You need to rename them to
FK_Customer_PrimaryEngineer
FK_Customer_AssignedEngineer
Update: you can have different column name and property name like so:
[Column("PrimaryEngId")]
[ForeignKey("Primary")]
public int? PrimaryID { get; set; }
I have a Page class that is to be associated with similar pages. Each association has additional information about the association. This is the class that has been defined as the representation of a Page.
public class Page {
[Key]
public virtual int Id { get; protected set; }
[Required]
[StringLength(32)]
public virtual string Name { get; set; }
[InverseProperty("Page")]
public virtual ICollection<Association> Associations { get; set; }
}
Each page has can be associated with any number of other pages. This is to be defined as a source and a target page. I do not mind if the association is unidirectional or bidirectional, either will be justified in my particular scenario (I prefer bidirectional associations, tough). This is the association class..
public class Association {
[Key, Column(Order = 0)]
public virtual int PageId { get; protected set; } // SOURCE
[Required]
public virtual Page Page { get; set; } // SOURCE
[Key, Column(Order = 1)]
public virtual int TargetId { get; protected set; } // TARGET
[Required]
public virtual Page Target { get; set; } // TARGET
[Required]
[StringLength(32)]
public virtual string InformationAboutTheAssociation { get; set; }
}
Now I have the following context ...
public class DbCtx : DbContext {
public DbSet<Association> Associations { get; set; }
public DbSet<Page> Pages { get; set; }
}
And the issue is that SQL Express is complaining about possible cyclic references (which is not the case, but it is over-protective). How do I solve the scheme that is generated to accept the described scenario?
Introducing FOREIGN KEY constraint 'FK_dbo.Associations_dbo.Pages_TargetId' on table 'Associations' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
Thanks!
RESPONSE
Do what the error tells you.
Specify ON DELETE NO ACTION or ON UPDATE NO ACTION. Since you have two foreign keys to the same entity, and model first (probably) inserts by default on delete cascade, you must disable this, because when a page is deleted, the association will try to be deleted by the first foreign key but will fail because of the second foreign key.
Modify 3
public class DbCtx : DbContext {
public DbSet<Association> Associations { get; set; }
public DbSet<Page> Pages { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder) {
modelBuilder.Entity<Association>()
.HasRequired(x => x.Page)
.WithMany(x => x.Associations)
.WillCascadeOnDelete(false);
}
}
I think this should work.
Deleting a Page entity
Because you don't have on delete cascade on the Association if you try and delete a Page it will fail if you have Association entities that depend on the Page entity you want to delete.
So when you want to delete a Page you must first delete all the associations referencing the Page. You have a foreign constraint (two of them actually) from the Association to the Page. Use only one of them and be consistent (either Page or Target).
Since you have asked this question I can only conclude you don't really know how SQL works so it is better if you also read a book about designing a database and using SQL.
I haven't used code first in EF but considering an Entity Relation diagram, Page has "1 to many" with Association and Association has two "1 to 1" with Page.
Isn't this cyclic because it seems like and it's a bad design.
Normalize the database.
If you would design the database (database first), you wouldn't need the relation "1 to many" between the Page and Association because you already have the relation "1 to 1" (two of them) from Association to Page.
So if you want to look for a specific association knowing the pagId you can have a select * from association where pageId or targetId = the id you are looking for.
If you would use EF with database first, you would have a back reference from page to association (what you are trying to do here) but not in the actual Entity Relation model of the database itself. They are virtual references.
EDIT:
I reread the question and the problem is the second reference from the Association to the Page. It is strange since the database first works fine with this case.
I will look into it.