I receive an exception when trying to replace the owned collection with the one I receive through API (EF Core 6).
System.InvalidOperationException: 'The instance of entity type 'Product' cannot be tracked because another instance with the same key value for {'Id'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.
Here is my model configuration:
public class Order
{
public int Id { get; set; }
public ICollection<OrderItem> OrderItems { get; set; }
}
public class OrderItem
{
public Product Product { get; set; }
public int Quantity { get; set; }
}
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
}
modelBuilder.Entity<Product>(x =>
{
x.HasKey(e => e.Id);
x.Property(e => e.Name);
});
modelBuilder.Entity<Order>(x =>
{
x.HasKey(e => e.Id);
x.OwnsMany(e => e.OrderItems, p =>
{
p.ToTable("OrderItems")
.WithOwner();
p.HasOne(e => e.Product).WithMany();
p.Property(e => e.Quantity);
});
});
Act:
//these are updated items received through API
var newItems = new List<OrderItem>
{
new OrderItem{ Product = new Product { Id = 2}, Quantity = 2},
new OrderItem{ Product = new Product { Id = 3}, Quantity = 3}
};
var existingOrder = _dbContext.Orders
.Include(o => o.OrderItems).ThenInclude(i => i.Product)
.Single(o => o.Id == 1);
// Existing OrderItems are already referencing Product with Id 2
existingOrder.OrderItems = newItems;
// Error occurs because Product with Id = 2 was already tracked
_dbContext.SaveChanges();
I know that the issue might be resolved by replacing Product with ProductId within my OrderItem class but I would rather prefer to keep my domain model as it is.
What is the best practice to perform such update?
it's all about understanding of the modeling. You can create a model response to update also, but just have to update manually by calling it.
you have existingOrder from the query include, then include like this I guess
var existingOrder = ...
existingOrder.OrderItems.Update(yourentity_OrderItem);
await _dbContext.SaveChangesAsync();
So this mean you have to retrieve each Product.id by a for, and update each new items, then savechanges.
Related
In my EF Core solution I have the following model:
public class Deal
{
public string Id { get; set; }
public ResponsiblePerson ResponsiblePerson1 { get; set; }
public ResponsiblePerson ResponsiblePerson2 { get; set; }
public ResponsiblePerson ResponsiblePerson3 { get; set; }
}
public class ResponsiblePerson
{
public string Id { get; set; }
public string Name { get; set; }
}
When I am trying to update Deal navigations properties:
private void UpdateResponsiblePersons(string dealId, string person1Id, string person2Id, string person3Id)
{
var existingdeal = _dbContext.Deals
.Include(d => d.ResponsiblePerson1)
.Include(d => d.ResponsiblePerson2)
.Include(d => d.ResponsiblePerson3)
.Single(d => d.Id == dealId);
existingDeal.ResponsiblePerson1 = new ResponsiblePerson { Id = person1Id };
existingDeal.ResponsiblePerson2 = new ResponsiblePerson { Id = person2Id };
existingDeal.ResponsiblePerson3 = new ResponsiblePerson { Id = person3Id };
_dbContext.Entry(deal.ResponsiblePerson1).State = EntityState.Unchanged;
_dbContext.Entry(deal.ResponsiblePerson3).State = EntityState.Unchanged;
_dbContext.Entry(deal.ResponsiblePerson3).State = EntityState.Unchanged;
_dbContext.SaveChanges();
}
EF often fails with
System.InvalidOperationException: The instance of entity type 'ResponsiblePerson' cannot be tracked because another instance with the key value '{Id: 1}' is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.
That is because sometimes existingdeal already contains the link to ResponsiblePerson with one of provided IDs in either ResponsiblePerson1 of ResponsiblePerson2 or ResponsiblePerson3 Navigation properties.
I know that one of possible solutions will be first to get ResponsiblePersons used for update from dbContext like
existingDeal.ResponsiblePerson1 = _dbContext.ResponsiblePersons.Find(person1Id)
But that means extra DB roundtrips.
Another solution is to expose foreign keys instead of navigation properties but it would make Deal model quite ugly.
Please advice me what is the best way of updating such references?
I have a Category table and it has a Parent Category, I try to iterate over all the categories and get the parents categories with it's Inverse Parent but some of them returns without the inverse parents from unknown reason.
Categories.cs
public partial class Categories
{
public Categories()
{
InverseParent = new HashSet<Categories>();
}
public int Id { get; set; }
public int? ParentId { get; set; }
public DateTime CreateDate { get; set; }
public bool? Status { get; set; }
public virtual Categories Parent { get; set; }
public virtual ICollection<Categories> InverseParent { get; set; }
}
This is how I try to iterate them to create a select list items:
var parentCategories = await _context.Categories.
Include(x => x.Parent).
Where(x => x.Status == true).
Where(x => x.Parent != null).
Select(x => x.Parent).
Distinct().
ToListAsync();
foreach (var parent in parentCategories)
{
SelectListGroup group = new SelectListGroup() { Name = parent.Id.ToString() };
foreach (var category in parent.InverseParent)
{
categories.Add(new SelectListItem { Text = category.Id.ToString(), Value = category.Id.ToString(), Group = group });
}
}
So the problem is that some of my parent categories returns all their children categories and some don't and I don't why.
There are several issues with that code, all having some explaination in the Loading Related Data section of the documentation.
First, you didn't ask EF Core to include InverseParent, so it's more logically to expect it to be always null.
What you get is a result of the following Eager Loading behavior:
Tip
Entity Framework Core will automatically fix-up navigation properties to any other entities that were previously loaded into the context instance. So even if you don't explicitly include the data for a navigation property, the property may still be populated if some or all of the related entities were previously loaded.
Second, since the query is changing it's initial shape (Select, Disctinct), it's falling into Ignored Includes category.
With that being said, you should build the query other way around - starting directly with parent categories and including InverseParent:
var parentCategories = await _context.Categories
.Include(x => x.InverseParent)
.Where(x => x.InverseParent.Any(c => c.Status == true)) // to match your query filter
.ToListAsync();
While you are including Include(x => x.Parent), you don't seem to do the same for InverseParent. This might affect your results exactly the way you describe. Would including it fix it?
parentCategories = await _context.Categories.
Include(x => x.Parent).
Include(x => x.InverseParent).
Where(x => x.Status == true).
Where(x => x.Parent != null).
Select(x => x.Parent).
Distinct().
ToListAsync();
foreach (var parent in parentCategories)
{
SelectListGroup group = new SelectListGroup() { Name = parent.Id.ToString() };
foreach (var category in parent.InverseParent)
{
categories.Add(new SelectListItem { Text = category.Id.ToString(), Value = category.Id.ToString(), Group = group });
}
}
UPD: Since you are selecting x => x.Parent anyway it might be necessary to use ThenInclude() method instead.
I have a base class called Entry:
[BsonDiscriminator(RootClass = true)]
[BsonKnownTypes(typeof(AccountEntry))]
public class Entry
{
public ObjectId Id { get; set; }
public string Register { get; set; }
}
With a derived class called AccountEntry as example
public class AccountEntry : Entry
{
public Account Account { get; set; }
}
When I try to do an Update, a compile time error shows that says, AccountEntry cannot be converted to Entry
var filter = Builders<AccountEntry>.Filter.Where(x => x.Id = id);
await context.Entries.UpdateOneAsync(filter, new AccountEntry()
{
Account = debitAccount,
}, new UpdateOptions() { IsUpsert = true });
Inserting the derived class does not cause the same problem.
Your filter needs to be of type Entry, not AccountEntry.
var filter = Builders<Entry>.Filter.Where(x => x.Id == id);
This is because filter is not covariant (I think that's the right one). So, the compiler can't just use a FilterDefinitionBuilder in place of a FilterDefinitionBuilder.
We have a ticket open to better handle derived types: https://jira.mongodb.org/browse/CSHARP-1194.
I want to retrieve an object plus its filtered/ordered collection property using EF 5. However, my current code throws an exception:
The Include path expression must refer to a navigation property
defined on the type. Use dotted paths for reference navigation
properties and the Select operator for collection navigation
properties
Here is the class of the object I want to retrieve:
public class EntryCollection
{
[Key]
public int Id { get; set; }
public ICollection<Entry> Entries { get; set; }
...
}
And here is the definition of Entry:
public class Entry
{
[Key]
public int Id { get; set; }
public DateTime Added { get; set; }
...
}
I wanted to retrieve the EntryCollection which contains only the most recent entries, so here is the code I tried:
using (var db = new MyContext())
{
return db.EntryCollections
.Include(ec => ec.Entries.OrderByDescending(e => e.Added).Take(5))
.SingleOrDefault(ec => ec.Foo == "bar');
}
Any ideas?
You cant use OrderBy inside an include.
what about the following
using (var db = new MyContext())
{
return db.EntryCollections
.Where(ec => ec.Foo == "bar")
.Select(ec=> new Something{Entries = ec.Entries.OrderByDescending(e => e.Added).Take(5) }, /*some other properties*/)
.SingleOrDefault();
}
or do it in two seperate queries
Changing order of elements in a simple list, doesn't stick in Entity Framework. The reason is pretty simple as the ordering information is never stored in the database.
Has anyone come across a generic implementation of ordered list which would work along with Entity Framework?
The requirement is that the user is allowed to reorder list of selected items, and the ordering of items need to be preserved.
Overview
Although there doesn't seem to be any 'magic' to implement this, there is a pattern that we have used to solve this problem, especially when dealing with hierarchies of objects. It boils down to three key things:
Build an Entity model separate from your Domain model. This has the benefit of providing a good separation of concerns, effectively allowing your domain model to be designed and changed without getting bogged down by persistence details.
Use AutoMapper to overcome the hassle of mapping between the Entity and Domain models.
Implement custom value resolvers to map the list in both directions.
The Magic
Because models often include hierarchical and cyclical references between objects, the following Map<>() method can be used to avoid StackOverflow errors during the custom mapping
private class ResolveToDomain : IValueResolver
{
ResolutionResult Resolve(ResolutionResult rr)
{
//...
((MappingEngine) rr.Context.Engine).Map<Product, ProductEntity>(rr.Context, subProduct)
//...
}
}
The Code
Domain Model. Note that the Subproducts list order is important.
class Product
{
public Product ParentProduct { get; set; }
public string Name { get; set; }
public IList<Product> Subproducts { get; set; }
}
Entity Model
class ProductEntity
{
public int Id { get; set; }
public ProductEntity ParentProduct { get; set; }
public string Name { get; set; }
public IList<ProductSubproductEntity> Subproducts { get; set; }
}
class ProductSubproductEntity
{
public int ProductId { get; set; }
public ProductEntity Product { get; set; }
public int Order { get; set; }
public ProductEntity Subproduct { get; set; }
}
Entity Framework Context
class Context : DbContext
{
public DbSet<ProductEntity> Products { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<ProductEntity>()
.HasOptional(e => e.ParentProduct);
modelBuilder.Entity<ProductSubproductEntity>()
.HasKey(e => new {e.ProductId, e.Order})
.HasRequired(e => e.Product)
.WithMany(e => e.Subproducts)
.HasForeignKey(e => e.ProductId);
base.OnModelCreating(modelBuilder);
}
}
AutoMapper configuration
class Mappings : Profile
{
protected override void Configure()
{
Mapper.CreateMap<Product, ProductEntity>()
.ForMember(m => m.Subproducts, a => a.ResolveUsing<ProductSubproductResolver>());
Mapper.CreateMap<ProductEntity, Product>()
.ForMember(m => m.Subproducts, a => a.ResolveUsing<ProductSubproductEntityResolver>());
base.Configure();
}
}
class ProductSubproductResolver : IValueResolver
{
public ResolutionResult Resolve(ResolutionResult rr)
{
var result = new List<ProductSubproductEntity>();
var subproductsSource = ((Product) rr.Context.SourceValue).Subproducts;
if (subproductsSource == null) return rr.New(null);
for (int i = 0; i < subproductsSource.Count; i++)
{
var subProduct = subproductsSource[i];
result.Add(new ProductSubproductEntity()
{
Product = (ProductEntity)rr.Context.DestinationValue,
Order = i,
Subproduct = ((MappingEngine) rr.Context.Engine).Map<Product, ProductEntity>(rr.Context, subProduct)
});
}
return rr.New(result);
}
}
class ProductSubproductEntityResolver: IValueResolver
{
public ResolutionResult Resolve(ResolutionResult rr)
{
var subproductEntitiesSource = ((ProductEntity) rr.Context.SourceValue).Subproducts;
if (subproductEntitiesSource == null) return rr.New(null);
var result = subproductEntitiesSource.OrderBy(p => p.Order).Select(p =>
((MappingEngine) rr.Context.Engine).Map<ProductEntity, Product>(rr.Context, p.Subproduct))
.ToList();
return rr.New(result);
}
}
Usage
private static IList<Product> CreateDomainProducts()
{
var result = new List<Product>();
var mainProduct1 = new Product()
{
Name = "T-Shirt"
};
var subProduct1 = new Product()
{
ParentProduct = mainProduct1,
Name = "T-Shirt (Medium)",
};
var subProduct2 = new Product()
{
ParentProduct = mainProduct1,
Name = "T-Shirt (Large)",
};
mainProduct1.Subproducts = new []
{
subProduct1,
subProduct2
};
var mainProduct2 = new Product()
{
Name = "Shorts"
};
result.Add(mainProduct1);
result.Add(mainProduct2);
return result;
}
static void Main(string[] args)
{
Mapper.Initialize(a => a.AddProfile<Mappings>());
Database.SetInitializer(new DropCreateDatabaseAlways<Context>());
var products = CreateDomainProducts();
var productEntities = Mapper.Map<IList<ProductEntity>>(products);
using (var ctx = new Context())
{
ctx.Products.AddRange(productEntities);
ctx.SaveChanges();
}
// Simulating a disconnected scenario...
using (var ctx = new Context())
{
var productEntity = ctx.Products
.Include(p => p.Subproducts)
.Include(p => p.Subproducts.Select(p2 => p2.Subproduct))
.OrderBy(p=>p.Name)
.ToList();
var productsResult = Mapper.Map<IList<Product>>(productEntity);
// Should be 'T-Shirt (Medium)'
Console.WriteLine(productsResult[1].Subproducts[0].Name);
// Should be 'T-Shirt (Large)'
Console.WriteLine(productsResult[1].Subproducts[1].Name);
}
}
Voila. Hope that helps!
No magic here. If you want to persist a specific order of items in a list (other than a reproducible order by e.g. name) you must store a sequence number in the database.
There wont be an implementation of this for reordering on the database. The data in the database is physically ordered by default by the clustered index which is in essence ordering by the primary key.
Why do you want to do this? EF encourages all ordering to be done via LINQ queries.
If you are looking to optimize lookups you can create additional non-clustered indexes on the database by modifying the code generated for Migrations :
CreateTable(
"dbo.People",
c => new
{
ID = c.Int(nullable: false, identity: true),
Name = c.String()
})
.PrimaryKey(t => t.ID)
.Index(t => t.Name); // Create an index
Note that this will not impact the physical ordering in the database but will speed lookups, although this need to be balanced by slower writes/updates.
to find a solution for this challenge I faced to an article by the following link:
User-defined Order in SQL
this article analyzed different approaches for generating order index value during changing the order of the list. I found the algorithm mentioned in this article so performant by minimum limitation. this algorithm called True Fractions and it generates order index like the following figure:
I have prepared a code sample that I implement this approach by EF Core and InMemory database.
.NET Fiddle Code Sample