Sample class structure
class Order
{
public int Id { get; set; }
public DateTime Date { get; set; }
public List<OrderDetail> Details { get; set; }
}
class OrderDetail
{
public int Id { get; set; }
public int Qty { get; set; }
public Item Item { get; set; }
}
class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
class ElectronicItem : Item
{
public MoreDetail Detail { get; set; }
}
class MoreDetail
{
public int Id { get; set; }
public string SomeData { get; set; }
}
In order to populate order object with all navigational properties, I wrote
context.Orders.Include("Details").Include("Details.Item")
I also want to load MoreDetail object, hence I tried
context.Orders.Include("Details").Include("Details.Item.Detail")
It didn't work. How to load complete Order object?
It is currently not possible but it is feature requested by community on User DataVoice as you already found. There is also related bug on MS Connect.
You simply cannot eager load navigation properties of derived types but you can load them with separate query:
var moreDetails = context.MoreDetails;
EF should automatically fix your navigation properties. If you use filtering on orders in your original query you must apply that filter in more details query as well:
var moreDetails = cotnext.MoreDetials.Where(m => m.Item.Order ....);
Related
LazyLoading is disabled on my project. I want to get Product which is Id = 1 with Category navigation property of it. But I need just Id and Name properties of Category. That's why I want Category navigation property to has only these two fields.Is it possible to create such a query ?
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public dobule Price{ get; set; }
public string Description { get; set; }
public bool IsDeleted { get; set; }
public DateTime CreatedDate { get; set; }
public DateTime ModifiedDate { get; set; }
public int CategoryId{ get; set; }
public Category Category{ get; set; }
}
public class Category
{
public int Id { get; set; }
public string Name { get; set; }
public dobule Description{ get; set; }
public Category IsDeleted { get; set; }
public DateTime CreatedDate { get; set; }
public DateTime ModifiedDate { get; set; }
}
If you only want a few specific fields you will need to select them explicitly. Something like this would work:
dbContext.Products
.Select(p => new Product
{
Id = p.Id,
Name = p.Name,
// etc... The fields you need from product go here
Category = new Category
{
Id = p.Category.Id,
Name = p.Category.Name
}
}
It might be better to have a Product and Category model class that only has the two fields. Now your method would return a Category object that lacks values for most fields which the caller might not expect. Depends on what exactly you're doing.
Depends if you know what do you want before calling the DB.
If you know what do you know, then you can use some 'Include' logic or the awnser from #Sangman or check docu here.
If you already have the entity in the memory and then you decide to load additional navigation property.
context.Entry(yourEntity).Reference(a => a.Category).Load();
More examples here.
I'm working on a cinema application which allows users to surf through movies, cinema places and allows them to buy or reserve tickets. If a user reserved a ticket online, then the ticket must be activated in 12 hours by sellerperson who also uses the same program. I need to show the ticket informations on grid and need to make editable. Here's my database classes that must be included in query and have relationship with Sale class. (I want to select objects from Sale class which includes ti's related classes: Ticket, customer, movie, status and saloon infos.
Sale Class:
public class Sale
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
[ForeignKey("CustomerId")]
public virtual Customer Customer { get; set; }
public int CustomerId { get; set; }
[ForeignKey("StatusId")]
public virtual Status Status { get; set; }
public int StatusId { get; set; }
public virtual Seller Seller { get; set; }
public DateTime SellDate { get; set; }
public double Price { get; set; }
[ForeignKey("TicketID")]
public virtual Ticket Ticket { get; set; }
public int TicketID { get; set; }
}
Ticket Class:
public class Ticket
{
public Ticket()
{
Seats = new List<Seat>();
}
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
[ForeignKey("MovieId")]
public virtual Movie Movie { get; set; }
public int MovieId { get; set; }
public virtual List<Seat> Seats { get; set; }
public virtual TimeSpan SeanceTime { get; set; }
public bool IsActive { get; set; }
public DateTime BuyDate { get; set; }
[ForeignKey("SaloonId")]
public virtual Saloon Saloon { get; set; }
public int? SaloonId { get; set; }
public string TicketNumber { get; set; }
}
Customer Class:
public class Customer
{
public Customer()
{
Sales = new List<Sale>();
CreditCards = new List<CreditCard>();
}
[Key]
public int UserID { get; set; }
public virtual List<Sale> Sales { get; set; }
public virtual User User { get; set; }
[DataType(DataType.CreditCard)]
public virtual List<CreditCard> CreditCards { get; set; }
}
User Class:
public class User
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public string Name { get; set; }
public string Surname { get; set; }
}
Status Class(Holds info of tickets. Bought or reserved.)
public class Status
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public bool IsRez { get; set; }
public bool IsBuy { get; set; }
public bool IsCancel { get; set; }
public bool IsPaid { get; set; }
}
Saloon Class:
public class Saloon
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public string Name { get; set; }
public double salePrices { get; set; }
}
Movie Class:
public class Movie
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }
public string Name { get; set; }
}
I can't edit because in my select query I'm using anonymous type for selection. My query code:
var Source = entities.Sales.Where(w => w.Ticket.Saloon.CinemaPlace.ID == seller.CinemaPlace.ID).Select(s => new
{
CustomerName = s.Customer.User.Name,
CustomerSurname = s.Customer.User.Surname,
SalePrice = s.Price,
s.Status.IsBuy,
s.Status.IsCancel,
s.Status.IsPaid,
s.Status.IsRez,
MovieName = s.Ticket.BuyDate,
s.Ticket.Movie.Name,
SaloonName = s.Ticket.Saloon.Name,
s.Ticket.SeanceTime,
s.Ticket.TicketNumber
}).ToList();
RezervationsGrid.DataSource = Source3;
But in the grid, the datas couldn't be edited. Then I tried to join every single table using Linq to Entities queries but it didn't help either. Is there a way make a datasource from my related objects that allows edit option in grid? Thanks.
Anonymous types (those that you can declare via the new operator in the Select method) cannot have writable properties in .NET. That's why the grid is not editable. To take advantage of in-place editing, you need to instantiate objects of a real CLR type.
For this, you can declare a special ViewModel class with public properties that you should populate with values in the Select method using object initializer.
.Select(s => new SaleViewModel() {
CustomerName = s.Customer.User.Name,
SalePrice = Price
})
Note that you should not move the property initialisation logic to the ViewModel constructor to use it this way:
.Select(s => new SaleViewModel(s))
The object initialiser is the expression tree, which Entity Framework can translate into an SQL query. The constructor is just a method reference, so Entity Framework will reject such an expression. If you would like to use this approach, you will need to call the ToList method before the Select.
SaleViewModel can have the method accepting the DbContext class to save changes.
You also can select the Sale instances and use complex property paths in columns' field names (such as "Customer.User.Name"). This can probably help you to simplify the saving logic, as you will not need to find a model specific to a certain view model and copy modified property values.
I recently used the following code
var errorCount =
split.Profiles.SelectMany(p => p.Logs)
.Count(l => l.LogTypeId == (int)LogType.Error);
errorCount returned zero because I forgot to include my logs table when I built the split entity.
How can I detect whether the split.Profiles.Logs collection has been eager loaded?
I am using Model First.
the class for Profile is
public partial class Profile
{
public Profile()
{
this.Log = new HashSet<Log>();
}
public int ProfileId { get; set; }
public int SplitId { get; set; }
public string Filename { get; set; }
public System.DateTime StartTime { get; set; }
public System.DateTime EndTime { get; set; }
public virtual ICollection<Log> Log { get; set; }
public virtual SplitUpload SplitUpload { get; set; }
}
#Hopeless you pointed me in the right direct. First I had to check the first collection was loaded. Then I needed to check that if it had any members then their child collection was also loaded
I have these two Models the logic is here One Post can have multiple Categories.
public class Post
{
public Post()
{
this.Categories = new HashSet<Category>();
}
public int Id { get; set; }
public string Title { get; set; }
public string Description { get; set; }
public string ShortDescription { get; set; }
public string PostImage { get; set; }
public string Thumbnail { get; set; }
public DateTime CreatedDate { get; set; }
public DateTime? PublishedDate { get; set; }
public string CreatedBy { get; set; }
public virtual ICollection<Category> Categories { get; set; }
}
public class Category
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Post> Posts { get; set; }
}
I have three static categories.
When I am trying to add new post its multiplexing CategoryTable creating new categories with same name ,And Mapping Them in to CategoryPostsTable.
The problem is here i want to map that data with existing categories. I dont want to add new category with same name.
I am using Repository Pattern how should i control that ? Is EF has some solution for that ?
I assume you have code like:
var post = new Post();
post.Categories.Add(cat);
context.Posts.Add(post);
...where cat is a Category object representing an existing category.
The latter Add method (DbSet.Add) doesn't only mark the received entity as Added but all entities in its object graph that are not attached to the context. So cat will also be marked as Added if it wasn't attached yet.
What you can do is
context.Entry(cat).State = System.Data.Entity.EntityState.Unchanged;
Now EF will only create the association to the category, but not insert a new category.
Been stuck on this for a while so i thought i would ask. I am sure there is something simple i am missing here. Trying to learn Asp.net mvc 4 on my own by building a simple app.
Here is the model:
public class Category
{
public int Id { get; set; }
[Required]
[StringLength(32)]
public string Name { get; set; }
//public virtual ICollection<Note> Notes { get; set; }
private ICollection<Note> notes;
public ICollection<Note> Notes
{
get
{
return this.notes ?? (this.notes = new List<Note>());
}
}
}
public class Note
{
public int Id { get; set; }
[Required]
public string Content { get; set; }
[Required]
[StringLength(128)]
public string Topic { get; set; }
public int CategoryId { get; set; }
public virtual Category Category { get; set; }
public virtual IEnumerable<Comment> Comments { get; set; }
public virtual ICollection<Tag> Tags {get; set;}
public Note()
{
Tags = new HashSet<Tag>();
}
}
public class Tag
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Note> Notes { get; set; }
public Tag()
{
Notes = new HashSet<Note>();
}
}
I call this method in a repository from the controller:
public IQueryable<Note> GetAll()
{
var query = _db.Notes.Include(x => x.Category).Include(y => y.Tags);
return query;
}
On the home controller i am trying to return a list of all the notes and wanted to include the category name that it belongs to as well as the tags that go with the note. At first the did not show up so i read some tutorials about eager loading and figured out how to get them to show.
However, my method is not that efficient. The mini-profiler is barking at me for duplicate queries because the navigation properties for category and tags are sending queries for the notes again. IS there any way to just return the properties i need for the category and tag objects?
I have tried several methods with no luck. I was hoping i could do something like this:
var query = _db.Notes.Include(x => x.Category.Name).Include(y => y.Tags.Name);
But i get an error: Cannot convert lambda expression to type 'string' because it is not a delegate type
I have seen that error before that was caused by some missing using statements so i already double checked that.
Any suggestions? Thanks for the help