I am trying to refactor my asp.net mvc + entity framework project to use repository pattern, and a unit of work. In the newest versions of asp.net mvc DbContext is creating automatically using a parameterized constructor, it looks like this:
public class SchoolContext : DbContext
{
public SchoolContext(DbContextOptions<SchoolContext> options)
: base(options)
{
}
public DbSet<Student> Students { get; set; }
public DbSet<Group> Groups { get; set; }
public DbSet<Course> Courses { get; set; }
}
How can I create an instance of this DbContext in unitOfWork class, what options should I write it the brackets?
P.S: I can't remove the parameters, cause they are used in program.cs in the next way
builder.Services.AddDbContext<SchoolContext>(options =>
options.UseSqlServer(builder.Configuration.GetConnectionString("SchoolContext") ?? throw new InvalidOperationException("Connection string 'SchoolContext' not found.")));
And I also can't add an emty constuctor, cause it will cause an error due to the above statement. (you can't have both constructors)
Thanks to the comments I figured it out, here what I was looking for:
In the class create an instance of context
private SchoolContext _context;
And then initialize it using a constructor like this
public UnitOfWork()
{
var contextOptions = new DbContextOptionsBuilder<SchoolContext>()
.UseSqlServer("Server=(localdb)\\mssqllocaldb;Database=Mentoring.Data;Trusted_Connection=True;MultipleActiveResultSets=true")
.Options;
_context = new SchoolContext(contextOptions);
}
I am Using Entity Framework 6.1.1
I have a class in one project, which include FBuyShopContext, another for models, and one Asp project with MVC 5
In my first project I have following
public class FBuyShopContext : DbContext
{
public FBuyShopContext()
: base("name=FBuyShopContext")
{
}
public virtual DbSet<Product> Admins { get; set; }
}
}
And a Product Model in a other Library project
public class Product
{
public Product()
{}
public int Id { get; set; }
[Required]
public string Name { get; set; }
}
my connection string is following
<connectionStrings>
<add name="FBuyShopContext" connectionString="data source=tschikovani\SQLEXPRESS;initial catalog=OnlineShop;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>
and when I want to add a new product into database in my controller
FBuyShopContext db = new FBuyShopContext();
Product new = new Product ();
new.Name = "Iphone";
db.Products.Add(new);
db.SaveChanges();
I have a following exception
An exception of type 'System.ArgumentException' occurred in EntityFramework.dll
keyword not supported: 'data source'.
Why this happened? connection string is fully right
I can see three things going on here:
1) DbContext's contructor should take the name of the connection string, therefore change it to just FBuyShopContext and not name=FBuyShopContext.
public class FBuyShopContext : DbContext
{
public FbuyShopContext() : base("FBuyShopContext") {}
}
2) Your connection string ends with a ", which is an invalid character. You should remove it.
3) You should specify your primary key on the model, either using the fluent API, or by data annotations:
public class Product {
[Key]
public int Id { get; set; }
[Required]
public string Name { get; set; }
}
I'm pretty sure the error you are getting is caused by 2), but 1) and 3) would have caused you problems later.
I have the following Entity class definition:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
Notice that table name is different than the class name. I also have a ClientUsers table which is a many-to-many mapping for clients and users. Problem is, when I try to access the webUser.Clients property I get the following exception:
"Invalid object name 'dbo.ClientWebUsers'."
Looks like Entity Framework is trying to guess the name of the third table, but it apparently was not smart enough to take into account the table attribute that I have there. How can I tell EF that it is ClientUsers and not ClientWebUsers? Also what rule does it follow to know which table name comes first and which one comes second in the new table name? I think it's not alphabetical order.
I'm using EF 5.0. Thanks!
From the looks of things you're using Code First, so I'll answer accordingly. If this is incorrect, please let me know.
I believe the convention being used to determine the name of the many-to-many table is determined by the order in which they occur as DbSet properties in your SomeContext : DbContext class.
As for forcing EntityFramework to name your table whatever you like, you can use the Fluent API in the OnModelCreating method of your SomeContext : DbContext class as follows:
public class DatabaseContext : DbContext
{
public DatabaseContext()
: base("SomeDB")
{
}
public DbSet<WebUser> Users { get; set; }
public DbSet<Client> Clients { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<WebUser>().HasMany(c => c.Clients)
.WithMany(p => p.WebUsers).Map(
m =>
{
m.MapLeftKey("ClientId");
m.MapRightKey("UserId");
m.ToTable("ClientUsers");
});
}
}
This assumes your classes are something like the following:
[Table("Users")]
public class WebUser
{
public virtual int Id { get; set; }
public virtual ICollection<Client> Clients { get; set; }
// more properties...
}
public class Client
{
public int Id { get; set; }
public ICollection<WebUser> WebUsers { get; set; }
// more properties
}
Finally, here's an integration test (NUnit) demonstrating the functionality working. You may need to drop your database before running it as Code First should want to update/migrate/recreate it.
[TestFixture]
public class Test
{
[Test]
public void UseDB()
{
var db = new DatabaseContext();
db.Users.Add(new WebUser { Clients = new List<Client> { new Client() } });
db.SaveChanges();
var webUser = db.Users.First();
var client = webUser.Clients.FirstOrDefault();
Assert.NotNull(client);
}
}
Edit: Link to relevant documentation for the Fluent API
Rowan's answer (adding here for reference):
Here is the information on how to configure a many-to-many table (including specifying the table name). The code you are after is something like:
modelBuilder.Entity<WebUser>()
.HasMany(u => u.Clients)
.WithMany(c => c.WebUsers)
.Map(m => m.ToTable("ClientUsers");
~Rowan
I use EF 5 with the code first approach. Now I try to define a "code" table in which I want to have several different codes (like address code, medium code, etc.). In this table I just have the following properties: ID (Guid), Name (String), Description (String) and a discriminator (in this case something like the type of the code: address code, medium code, etc.).
So I defined the following base class:
public abstract class Code : EntityBase
{
public string Name { get; set; }
public string Beschreibung { get; set; }
}
Then I derived two classes from code
public class AddressCode : Code {}
public class MediumCode : Code {}
The class EntityBase is abstract and just defines the Id property, we use it for every POCO class...
The goal is that I can use AddressCode as a property on my address POCO class:
public class Adresse : EntityBase
{
#region Properties
public string Name1 { get; set; }
public virtual AddressCode AddressCode { get; set; }
#endregion
}
The question now is, how can I explain EF how to do that? Anyone can help?
Thanks
Marco
Thanks for your answer!
I tried to do it like you said. Unfortunately I get an error because of my EntityBase class:
public abstract class EntityBase
{
#region Properties
public virtual Guid Id { get; set; }
public virtual bool IsValid
{
get
{
{
return Validate();
}
}
}
[NotMappedAttribute]
public virtual IList<ValidationFailure> ValidationFailures { get; set; }
#endregion
#region Methods
private bool Validate()
{
var validatorFactory = new AttributedValidatorFactory();
IValidator validator = validatorFactory.GetValidator(GetType());
if (validator == null)
{
return true;
}
ValidationResult validationResult = validator.Validate(this);
ValidationFailures = validationResult.Errors;
return validationResult.IsValid;
}
#endregion
}
The error message is:
You cannot use Ignore method on the property 'ValidationFailures' on type 'Entities.AdresseCode' because this type inherits from the type 'Entities.EntityBase' where this property is mapped. To exclude this property from your model, use NotMappedAttribute or Ignore method on the base type.
As you can see I already defined the property ValidationFailures as NotMapped but still I get this error.. Do you have an idea?
Thanks
Marco
Just create a context (derived from DbContext)
public class AddressesDb : DbContext
{
public DbSet<Code> Codes { get; set; }
public DbSet<Adresse> Adressen { get; set; }
}
And (when used in code) EF will create a database with default table and column names. It will create a discriminator column of type text (nvarchar) which will contain the names of the classes that derive from Code.
If you want different names and/or types you should either use data annotations or fluent API to configure these.
Finally I got it work!
In the DBContext be aware to define DbSets for the code derived classes before all the other POCO's and then it works!
I have a table in my database called SEntries (see below the CREATE TABLE statement). It has a primary key, a couple of foreign keys and nothing special about it. I have many tables in my database similar to that one, but for some reason, this table ended up with a "Discriminator" column on the EF Proxy Class.
This is how the class is declared in C#:
public class SEntry
{
public long SEntryId { get; set; }
public long OriginatorId { get; set; }
public DateTime DatePosted { get; set; }
public string Message { get; set; }
public byte DataEntrySource { get; set; }
public string SourceLink { get; set; }
public int SourceAppId { get; set; }
public int? LocationId { get; set; }
public long? ActivityId { get; set; }
public short OriginatorObjectTypeId { get; set; }
}
public class EMData : DbContext
{
public DbSet<SEntry> SEntries { get; set; }
...
}
When I try to add a new row to that table, I get the error:
System.Data.SqlClient.SqlException: Invalid column name 'Discriminator'.
This problem only occurs if you are inheriting your C# class from another class, but SEntry is not inheriting from anything (as you can see above).
In addition to that, once I get the tool-tip on the debugger when I mouse over the EMData instance for the SEntries property, it displays:
base {System.Data.Entity.Infrastructure.DbQuery<EM.SEntry>} = {SELECT
[Extent1].[Discriminator] AS [Discriminator],
[Extent1].[SEntryId] AS [SEntryId],
[Extent1].[OriginatorId] AS [OriginatorId],
[Extent1].[DatePosted] AS [DatePosted],
[Extent1].[Message] AS [Message],
[Extent1].[DataEntrySource] AS [DataE...
Any suggestions or ideas where to get to the bottom of this issue? I tried renaming the table, the primary key and a few other things, but nothing works.
SQL-Table:
CREATE TABLE [dbo].[SEntries](
[SEntryId] [bigint] IDENTITY(1125899906842624,1) NOT NULL,
[OriginatorId] [bigint] NOT NULL,
[DatePosted] [datetime] NOT NULL,
[Message] [nvarchar](500) NOT NULL,
[DataEntrySource] [tinyint] NOT NULL,
[SourceLink] [nvarchar](100) NULL,
[SourceAppId] [int] NOT NULL,
[LocationId] [int] NULL,
[ActivityId] [bigint] NULL,
[OriginatorObjectTypeId] [smallint] NOT NULL,
CONSTRAINT [PK_SEntries] PRIMARY KEY CLUSTERED
(
[SEntryId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [dbo].[SEntries] WITH CHECK ADD CONSTRAINT [FK_SEntries_ObjectTypes] FOREIGN KEY([OriginatorObjectTypeId])
REFERENCES [dbo].[ObjectTypes] ([ObjectTypeId])
GO
ALTER TABLE [dbo].[SEntries] CHECK CONSTRAINT [FK_SEntries_ObjectTypes]
GO
ALTER TABLE [dbo].[SEntries] WITH CHECK ADD CONSTRAINT [FK_SEntries_SourceApps] FOREIGN KEY([SourceAppId])
REFERENCES [dbo].[SourceApps] ([SourceAppId])
GO
ALTER TABLE [dbo].[SEntries] CHECK CONSTRAINT [FK_SEntries_SourceApps]
GO
Turns out that Entity Framework will assume that any class that inherits from a POCO class that is mapped to a table on the database requires a Discriminator column, even if the derived class will not be saved to the DB.
The solution is quite simple and you just need to add [NotMapped] as an attribute of the derived class.
Example:
class Person
{
public string Name { get; set; }
}
[NotMapped]
class PersonViewModel : Person
{
public bool UpdateProfile { get; set; }
}
Now, even if you map the Person class to the Person table on the database, a "Discriminator" column will not be created because the derived class has [NotMapped].
As an additional tip, you can use [NotMapped] to properties you don't want to map to a field on the DB.
Here is the Fluent API syntax.
http://blogs.msdn.com/b/adonet/archive/2010/12/06/ef-feature-ctp5-fluent-api-samples.aspx
class Person
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string FullName {
get {
return this.FirstName + " " + this.LastName;
}
}
}
class PersonViewModel : Person
{
public bool UpdateProfile { get; set; }
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// ignore a type that is not mapped to a database table
modelBuilder.Ignore<PersonViewModel>();
// ignore a property that is not mapped to a database column
modelBuilder.Entity<Person>()
.Ignore(p => p.FullName);
}
I just encountered this and my problem was caused by having two entities both with the System.ComponentModel.DataAnnotations.Schema.TableAttribute referring to the same table.
for example:
[Table("foo")]
public class foo
{
// some stuff here
}
[Table("foo")]
public class fooExtended
{
// more stuff here
}
changing the second one from foo to foo_extended fixed this for me and I'm now using Table Per Type (TPT)
I had a similar problem, not exactly the same conditions and then i saw this post. Hope it helps someone. Apparently i was using one of my EF entity models a base class for a type that was not specified as a db set in my dbcontext. To fix this issue i had to create a base class that had all the properties common to the two types and inherit from the new base class among the two types.
Example:
//Bad Flow
//class defined in dbcontext as a dbset
public class Customer{
public int Id {get; set;}
public string Name {get; set;}
}
//class not defined in dbcontext as a dbset
public class DuplicateCustomer:Customer{
public object DuplicateId {get; set;}
}
//Good/Correct flow*
//Common base class
public class CustomerBase{
public int Id {get; set;}
public string Name {get; set;}
}
//entity model referenced in dbcontext as a dbset
public class Customer: CustomerBase{
}
//entity model not referenced in dbcontext as a dbset
public class DuplicateCustomer:CustomerBase{
public object DuplicateId {get; set;}
}
Another scenario where this occurs is when you have a base class and one or more subclasses, where at least one of the subclasses introduce extra properties:
class Folder {
[key]
public string Id { get; set; }
public string Name { get; set; }
}
// Adds no props, but comes from a different view in the db to Folder:
class SomeKindOfFolder: Folder {
}
// Adds some props, but comes from a different view in the db to Folder:
class AnotherKindOfFolder: Folder {
public string FolderAttributes { get; set; }
}
If these are mapped in the DbContext like below, the "'Invalid column name 'Discriminator'" error occurs when any type based on Folder base type is accessed:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Folder>().ToTable("All_Folders");
modelBuilder.Entity<SomeKindOfFolder>().ToTable("Some_Kind_Of_Folders");
modelBuilder.Entity<AnotherKindOfFolder>().ToTable("Another_Kind_Of_Folders");
}
I found that to fix the issue, we extract the props of Folder to a base class (which is not mapped in OnModelCreating()) like so - OnModelCreating should be unchanged:
class FolderBase {
[key]
public string Id { get; set; }
public string Name { get; set; }
}
class Folder: FolderBase {
}
class SomeKindOfFolder: FolderBase {
}
class AnotherKindOfFolder: FolderBase {
public string FolderAttributes { get; set; }
}
This eliminates the issue, but I don't know why!
I get the error in another situation, and here are the problem and the solution:
I have 2 classes derived from a same base class named LevledItem:
public partial class Team : LeveledItem
{
//Everything is ok here!
}
public partial class Story : LeveledItem
{
//Everything is ok here!
}
But in their DbContext, I copied some code but forget to change one of the class name:
public class MFCTeamDbContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//Other codes here
modelBuilder.Entity<LeveledItem>()
.Map<Team>(m => m.Requires("Type").HasValue(ItemType.Team));
}
public class ProductBacklogDbContext : DbContext
{
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//Other codes here
modelBuilder.Entity<LeveledItem>()
.Map<Team>(m => m.Requires("Type").HasValue(ItemType.Story));
}
Yes, the second Map< Team> should be Map< Story>.
And it cost me half a day to figure it out!
Old Q, but for posterity...it also also happens (.NET Core 2.1) if you have a self-referencing navigation property ("Parent" or "Children" of the same type) but the Id property name isn't what EF expects. That is, I had an "Id" property on my class called WorkflowBase, and it had an array of related child steps, which were also of type WorkflowBase, and it kept trying to associate them with a non-existent "WorkflowBaseId" (the name i suppose it prefers as a natural/conventional default). I had to explicitly configure it using HasMany(), WithOne(), and HasConstraintName() to tell it how to traverse. But I spent a few hours thinking the problem was in 'locally' mapping the object's primary key, which i attempted to fix a bunch of different ways but which was probably always working.
this error happen with me because I did the following
I changed Column name of table in database
(I did not used Update Model from database in Edmx) I Renamed manually Property name to match the change in database schema
I did some refactoring to change name of the property in the class to be the same as database schema and models in Edmx
Although all of this, I got this error
so what to do
I Deleted the model from Edmx
Right Click and Update Model from database
this will regenerate the model, and entity framework will not give you this error
hope this help you