I have recently switched to Entity Framework Core with CosmosDB. Created context and tried to pull the data from existing cosmos container.
My context looks like this:
public class CosmosContext : DbContext
{
public string ConnectionString { get; set; }
public string DbName { get; set; }
public DbSet<ActivityLog> ActivityLog { get; set; }
public CosmosContext(
DbContextOptions options,
string connectionString,
string dbName) : base(options)
{
ConnectionString = connectionString;
DbName = dbName;
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseCosmos(ConnectionString, databaseName: DbName);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<ActivityLog>().ToContainer("ActivityLog");
}
}
Activity log like that:
public class ActivityLog
{
public string PartitionKey { get; set; }
public string CreatedDate { get; set; }
public string EntityID { get; set; }
public string ModifiedBy { get; set; }
public string CreatedBy { get; set; }
public string Action { get; set; }
public string Type { get; set; }
public string Object { get; set; }
public string id { get; set; }
}
Data in Azure currently is:
But when I try to query the data it's always null:
var ana = new CosmosContext(new DbContextOptions<CosmosContext>(),
_connectionString,
_databaseName);
var b = await ana.ActivityLog.FirstAsync();
I can create new containers just fine, however I need to work with the existing data. I'm pretty sure it's not recognized by the model binder but I cannot figure out why.
Related
I try to create the following database design with EF Core (code-first)
Entity "Recipe" can have a list of type "Resource"
Entity "Shop" can have a single "Resource"
Entity "InstructionStep" can have a list of type "Resource"
If I delete a resource from the "Recipe", "InstructionStep" (collections) or from the "Shop" (single-property) then the corresponding "Resource" entity should be also deleted. (Cascade Delete)
I already tried several things with and without mapping tables but none of my approach was successful.
Another idea was to have a property "ItemRefId" in the "Resource" entity to save the "RecipeId/ShopId/InstructionStepId" but I don't get it to work...
Example Classes:
public class Recipe
{
public int RecipeId { get; set; }
public string Title { get; set; }
public ICollection<RecipeResource> Resources { get; set; } = new List<RecipeResource>();
}
public class Shop
{
public int ShopId { get; set; }
public string Title { get; set; }
public Resource Logo { get; set; }
}
public class Resource
{
public int ResourceId { get; set; }
public string Path { get; set; }
public int ItemRefId { get; set; }
}
public class InstructionStep
{
public string InstructionStepId { get; set; }
public string Title { get; set; }
public ICollection<RecipeResource> Resources { get; set; } = new List<RecipeResource>();
}
Any suggestions? Many thanks in advance.
That's not cascade delete. Cascade delete would be when a Recipe is deleted, all of the related Resources are deleted as well.
In EF Core 3, you can use Owned Entity Types for this. The generated relational model is different from what you are proposing, in that Recipe_Resource and InstructionStep_Resource will be seperate tables, and Shop.Logo will be stored in columns on the Shop table. But that's the correct relational model. Having one Resource table with some rows referencing a Recipe and some rows referencing an InstructionStep is a bad idea.
This scenario is sometimes called a "Strong Relationship" where the identity of the related entity is dependent on the main entity, and should be implemented in the relational model by having the the Foreign Key columns be Primary Key columns on the dependent entity. That way there's no way remove a Recipe_Resource without deleting it.
eg
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
using System.Linq;
namespace EfCore3Test
{
public class Recipe
{
public int RecipeId { get; set; }
public string Title { get; set; }
public ICollection<Resource> Resources { get; } = new List<Resource>();
}
public class Shop
{
public int ShopId { get; set; }
public string Title { get; set; }
public Resource Logo { get; set; }
}
public class Resource
{
public int ResourceId { get; set; }
public string Path { get; set; }
public int ItemRefId { get; set; }
}
public class InstructionStep
{
public string InstructionStepId { get; set; }
public string Title { get; set; }
public ICollection<Resource> Resources { get; } = new List<Resource>();
}
public class Db : DbContext
{
public DbSet<Recipe> Recipes { get; set; }
public virtual DbSet<Shop> Shops { get; set; }
public virtual DbSet<InstructionStep> InstructionSteps { get; set; }
private static readonly ILoggerFactory loggerFactory = LoggerFactory.Create(builder =>
{
builder.AddFilter((category, level) =>
category == DbLoggerCategory.Database.Command.Name
&& level == LogLevel.Information).AddConsole();
});
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseLoggerFactory(loggerFactory)
.UseSqlServer("Server=.;database=EfCore3Test;Integrated Security=true",
o => o.UseRelationalNulls());
base.OnConfiguring(optionsBuilder);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Shop>().OwnsOne(p => p.Logo);
modelBuilder.Entity<InstructionStep>().OwnsMany(p => p.Resources);
modelBuilder.Entity<Recipe>().OwnsMany(p => p.Resources);
}
}
class Program
{
static void Main(string[] args)
{
using var db = new Db();
db.Database.EnsureDeleted();
db.Database.EnsureCreated();
var r = new Recipe();
r.Resources.Add(new Resource() { ItemRefId = 2, Path = "/" });
db.Recipes.Add(r);
db.SaveChanges();
r.Resources.Remove(r.Resources.First());
db.SaveChanges();
var s = new Shop();
s.Logo = new Resource { ItemRefId = 2, Path = "/" };
db.Shops.Add(s);
db.SaveChanges();
s.Logo = null;
db.SaveChanges();
}
}
}
I have a postgres database and using asp.net core mvc (+ ef). The database is created correctly. I have two tables 'Module' and 'ModuleMenu'. I want to get all the menu's for a given module but I keep on failing to create the linq query.
Situation
Model: Module.cs
namespace project.Model
{
public class Module
{
[Required]
public string ID { get; set; }
[Required]
public string Name { get; set; }
[Required]
public string Description { get; set; }
}
}
Model: ModuleMenu.cs
namespace project.Models
{
public class ModuleMenu
{
[Required]
public string ID { get; set; }
public int ModuleID { get; set; }
[Required]
public string Title { get; set; }
[ForeignKey("ModuleID")]
public virtual Module Module { get; set; }
}
}
ApplicationDbContext.cs
namespace project.Data
{
public class ApplicationDbContext
{
public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
: base(options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
}
public DbSet<Module> Modules { get; set; }
public DbSet<ModuleMenu> ModuleMenus { get; set; }
}
}
Query
public List<ModuleMenu> GetModuleMenus(){
var query = from m in _dbContext.ModuleMenus
join mod in _dbContext.Modules on
m.ModuleID equals mod.ID
select m;
return query.ToList();
}
Error
fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[0]
An exception was thrown attempting to execute the error handler.
System.NullReferenceException: Object reference not set to an instance of an object.
Can anyone help me to correctly create the query?
Is this part correct in your code?
public int ModuleID { get; set; }
It seems that you might have had an error in the type used for the fk.
Below I changed the type to be string rather than int.
public string ModuleID { get; set; }
based on that update, the query could look like this.
public ModuleMenu[] GetModuleMenusForModule(string moduleId)
{
return _dbContext.ModuleMenus.Where(x => x.ModuleID == moduleId).ToArray();
}
I would expect that model to error (ModelID and ID are incompatible types). If that were correct, your code should work. Or simpler:
public List<ModuleMenu> GetModuleMenus()
{
return _dbContext.ModuleMenus.ToList();
}
I created some classes and a table in db for those classes with migration. I tested my code by adding some data to the classes,saved by EF and saw the data saved properly in db.
Later when I created a view in db and maped that view in code the problems started. When I tried to query this way:
using (var db = new TestDBContext())
{
var listMyViews = db.vwCustomer.ToList();
}
I was getting an error message like
Additional information: The model backing the 'TestDBContext' context has changed since the database was created. Consider using Code First Migrations to update the database
So EF is telling me to migrate features to create view in db but view exists already. So why do I need to recreate it by migration?
my full code with view mapping and class
public class CustomerBase
{
public int CustomerID { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Address1 { get; set; }
public string Address2 { get; set; }
public string Phone { get; set; }
public string Fax { get; set; }
}
public class Customer : CustomerBase
{
public virtual List<Addresses> Addresses { get; set; }
}
public class Addresses
{
[Key]
public int AddressID { get; set; }
public string Address1 { get; set; }
public string Address2 { get; set; }
public bool IsDefault { get; set; }
public virtual List<Contacts> Contacts { get; set; }
public int CustomerID { get; set; }
public virtual Customer Customer { get; set; }
}
public class Contacts
{
[Key]
public int ContactID { get; set; }
public string Phone { get; set; }
public string Fax { get; set; }
public bool IsDefault { get; set; }
public int AddressID { get; set; }
public virtual Addresses Customer { get; set; }
}
public class vwCustomer
{
public int CustomerID { get; set; }
public string FirstName { get; set; }
}
public class TestDBContext : DbContext
{
public TestDBContext()
: base("name=TestDBContext")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new vwCustomerConfiguration());
}
public DbSet<Customer> Customer { get; set; }
public DbSet<Addresses> Addresses { get; set; }
public DbSet<Contacts> Contacts { get; set; }
public DbSet<vwCustomer> vwCustomer { get; set; }
}
public class vwCustomerConfiguration : EntityTypeConfiguration<vwCustomer>
{
public vwCustomerConfiguration()
{
this.HasKey(t => t.CustomerID);
this.ToTable("vwCustomer");
}
}
Later I tried to see if any migration is pending issuing Add-Migration "My_vwCustomer". I saw new migration code being added as below. It seems there is no migration pending.
public partial class My_vwCustomer : DbMigration
{
public override void Up()
{
CreateTable(
"dbo.vwCustomers",
c => new
{
CustomerID = c.Int(nullable: false, identity: true),
FirstName = c.String(),
})
.PrimaryKey(t => t.CustomerID);
}
public override void Down()
{
DropTable("dbo.vwCustomers");
}
}
Another way we can do it and it solve my problem. see the code.
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
Database.SetInitializer<YourDbContext>(null);
base.OnModelCreating(modelBuilder);
}
code taken from here https://stackoverflow.com/a/6143116/6188148
we can follow this approach too.
public partial class AddingvwCustomer : DbMigration
{
public override void Up()
{
}
public override void Down()
{
}
}
i guess this will works too but not tested myself.
we can use the Fluent API to configure it using the Ignore method:
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Ignore<MyClass>();
}
thanks
I'm new to Entity Framework. At the moment I'm having a problem - when I try to insert a new User object into the database (using method RegisterNewUser), I keep getting an error:
Violation of PRIMARY KEY constraint 'PK__Users__3214EC07705D23AE'. Cannot insert duplicate key in object 'dbo.Users'. The duplicate key value is (0).
There are some similar questions here, but none of these answers have helped me.
public void RegisterNewUser(String uName, String uPass, String fName, String lName, String email)
{
User user = new User();
user.Username = uName;
user.Password = uPass;
user.FirstName = fName;
user.LastName = lName;
user.Email = email;
Time time = new Time();
time.Time1 = DateTime.Now;
user.Times.Add(time);
ur.AddUser(user);
}
Time and User objects:
public partial class Time
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public int UserId { get; set; }
public System.DateTime Time1 { get; set; }
public virtual User User { get; set; }
}
public partial class User
{
public User()
{
this.Times = new HashSet<Time>();
}
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int Id { get; set; }
public string Username { get; set; }
public string Password { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public string Email { get; set; }
public virtual ICollection<Time> Times { get; set; }
}
Repository file
public class UsersRepository
{
UsersDBContext userDBContext = new UsersDBContext();
public List<User> GetUsers()
{
return userDBContext.Users.Include("Times").ToList();
}
public void AddUser(User user)
{
userDBContext.Users.Add(user);
userDBContext.SaveChanges();
}
}
And context
public partial class UsersDBContext : DbContext
{
public UsersDBContext() : base("name=UsersDBContext")
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
throw new UnintentionalCodeFirstException();
}
public virtual DbSet<Time> Times { get; set; }
public virtual DbSet<User> Users { get; set; }
}
I have no idea how to solve this so any suggestions would be very helpful
set a value of Id field
or
define the Id field as autoincrement
I am getting this error in my .Net MVC 4 web application:
The property 'Username' cannot be configured as a navigation property. The
property must be a valid entity type and the property should have a non-abstract
getter and setter. For collection properties the type must implement
ICollection<T> where T is a valid entity type.
I am very new to Entity Framework and I can't seem to get around this issue. Here is some code:
//DB Context
public class EFDbContext : DbContext
{
public DbSet<User> Users { get; set; }
public DbSet<Role> Roles { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>().HasMany(u => u.Roles).WithMany(r => r.Users).Map(x => x.MapLeftKey("Username").MapRightKey("RoleName").ToTable("Users_Roles"));
}
}
//Entity Classes
public class User
{
[Key]
public string Username { get; set; }
public string Password { get; set; }
public string Email { get; set; }
public string Comment { get; set; }
public int Level { get; set; }
public string PasswordQuestion { get; set; }
public string PasswordAnswer { get; set; }
public bool IsApproved { get; set; }
public DateTime LastActivityDate { get; set; }
public DateTime LastLoginDate { get; set; }
public DateTime LastPasswordChangedDate { get; set; }
public DateTime CreationDate { get; set; }
public bool IsOnLine { get; set; }
public bool IsLockedOut { get; set; }
public DateTime LastLockedOutDate { get; set; }
public int FailedPasswordAttemptCount { get; set; }
public DateTime FailedPasswordAttemptWindowStart { get; set; }
public int FailedPasswordAnswerAttemptCount { get; set; }
public DateTime FailedPasswordAnswerAttemptWindowStart { get; set; }
[InverseProperty("RoleName")]
public virtual ICollection<Role> Roles { get; set; }
public override string ToString()
{
return this.Username;
}
}
public class Role
{
[Key]
public string RoleName { get; set; }
public int Level { get; set; }
[InverseProperty("Username")]
public virtual ICollection<User> Users { get; set; }
public override string ToString()
{
return this.RoleName;
}
}
//Repository
public class EFUsersRepository : IUsersRepository
{
private EFDbContext context = new EFDbContext();
public IQueryable<User> Users
{
get { return context.Users; }
}
public User GetUser(string username)
{
return context.Users.Find(username); //THIS IS WHERE THE CRASH OCCURS
}
}
//DB Setup
Table Users, Role and Users_Role. Users_Role is a simple linking table with [username, role] columns both of type varchar.
The database tables columns & types match the two classes above (User,Role).
I inherited this project which was unfinished but I can't get it to run successfully. Any help understanding what the issue is would be helpful. Thanks!
It might be that Entity Framework is updated. Easiest way will be to recreate the DataModel.
Even if the previous programmer did not use Entity Data Mode, you can at least copy the auto generated code such as EFDbContext, Users and Roles classes.
It turns out, after commenting out enough items all day long, the the following lines are what caused this error for me:
[InverseProperty("RoleName")] //In file User.cs (as shown above)
[InverseProperty("UserName")] //in file Role.cs (as shown above)
I am still learning Entity Framework and I don't know why this was the solution, but it stopped the error which I reported above.
I hope that this helps someone else and if anyone wants to help me understand what the issue was in detail, please feel free. I am eager to learn.