This my main class
public partial class MainAcc
{
public int Id { get; set; }
public string Type1 { get; set; }
public string Type2 { get; set; }
public string Type3 { get; set; }
}
and in EDMX design i make new entity base type MainAcc, i delete some column that i want to move in EDMX design, so it become like this after i save
public partial class MainAcc
{
public int Id { get; set; }
public string Type1 { get; set; }
}
public partial class ChildAcc : MainAcc
{
public string Type2 { get; set; }
public string Type3 { get; set; }
}
In design my ChildAcc entity use table map of MainAcc. and after all i got error like this:
Error 3032: Problem in mapping fragments starting at lines 2877, 2907:EntityTypes MyModel.MainAcc, MyModel.ChildAcc are being mapped to the same rows in table MainAcc. Mapping conditions can be used to distinguish the rows that these types are mapped to.
That error in text editor is in MainAcc.
Looks like you can't do this. I think these should be two different tables, but they can be related by some foreign key.
I tried Database First and Model First and the script I ended up adding showed that this would be two different tables related to each other.
Perhaps you expect to have one-to-one or one-to-many relationships, but that doesn't happen within a single table. If you go the Database First way, changing the model may result in an inconsistency with the current context. If the Model First method is adopted, two tables will be automatically generated after the model relationship is established.
I also tried to use table splitting for table mapping, but there are some limitations for dependent entity types, and derived types cannot be mapped to the same table.
Helpful Links:
Advanced table mapping
Model First
Configure One-to-Many Relationships in EF 6
This is just my opinion, hope this helps you. Please help me correct if my understanding is wrong.
Related
I currently have a problem for a project where I need to create many-to-many relationships on the same class. I have a class named "Company" where I have some attributes. The relationship I want to create is:
One or more than one company can have one or more competitor. Where a competitor is in fact a company.
I already tried many solutions found on Internet but it seems not to be a good idea to represent the entity relationship I want to have and an easy way to use it in my model.
Here is my class:
public class Company
{
public int Id { get; set; }
public string CompanyName { get; set; }
public string CommercialName { get; set; }
...
}
I tried to add in this class the following line:
public ICollection<Company> Concurrents { get; set; }
But EF code first add a new column "company_id" in my "company" table.
What's the best way to add a list of concurrent in this class that is represented by a new table in my DB with 2 column representing the "Id" of company objects?
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 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 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
I have a system where I need to be able to add a Comment field onto Customer and Location models but I cannot touch the schema of the existing tables. However, I can add a Comments table. I have simplified this example. We would like the ability to add this Comment to more models moving forward they all use a Guid as Id.
This existing system is a 3rd party system with its own data access layer.
We are just starting to get into NHibernate. From what I can tell it looks like a Join map.
Example:
public class Customer
{
public Guid Id { get; private set; }
public string FirstName { get; private set; }
public string LastName { get; private set; }
public string Comment { get; set; }
}
public class Location
{
public Guid Id { get; private set; }
public string Name { get; private set; }
public string Address { get; private set; }
public string Comment { get; set; }
}
Note: we are sure we want the Comment as a 1-to-1 relationship and not a 1-to-many.
How do I configure a separate table just capture Id and Comment? I'm looking for the right terminology to use. I'm looking for examples with XML (and if possible Fluent config). I would like to keep the Comments for all objects in one table. Thanks.
If you can add Comment table (and corresponding key columns in the existing tables) than fluent mapping can look like
public class CustomerMap : ClassMap<Customer>{
public CustomerMap(){
//...other columns mappings
References(c=>c.Comment).Column("CommentId");
}
}
And repeat it for other entities as well. You can set desired fetch-mode(join) and other action there as well. I have wrote References there (so many-to-one) but if you need one-to-one mapping it is not a big difference
If you can't change the database schema your options are very limited.
MAYBE, you can do it using the mapping.
Take a look here:
http://ayende.com/blog/3961/nhibernate-mapping-join
Try to use the same column name in mapping for all entities.