I have some entities
public class Post
{
public Guid Id { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public Guid[] TagIds { get; set; }
public ICollection<Tag> Tags { get; set; }
}
public class Tag
{
public string Id { get; set; }
public string Name { get; set; }
}
How to build relations if posts.tag_ids is uuid[]?
I want to use
_dbContext.Posts.Include(x => x.Tags)
Expecting SQL
select * from posts p
left join tags t on t.id = any(p.tag_ids)
This
public Guid[] TagIds { get; set; }
is not how relational databases model relationships. If you want to relate the entities, try this instead:
public class Post
{
public Guid Id { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public ICollection<Tag> Tags { get; set; }
}
public class Tag
{
public string Id { get; set; }
public string Name { get; set; }
public ICollection<Post> Posts { get; set; }
}
It will create a linking table behind the scenes.
Related
I have a question. I created a table with many to many relationships as below. What code should I write so that I can enter multiple categories when adding a product to the database?
I would be glad if you explain with an example.
For example, I can enter product.name information with the name information I received from the user, but I do not know how to save data in the relevant tables.
public class Category
{
public int CategoryId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public List<ProductCategory> ProductCategories { get; set; }
}
public class Product
{
public int ProductId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public double? Price { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public bool IsApproved { get; set; }
public bool IsHome { get; set; }
public List<ProductCategory> ProductCategories { get; set; }
}
public class ProductCategory
{
public int CategoryId { get; set; }
public Category Category { get; set; }
public int ProductId { get; set; }
public Product Product { get; set; }
}
You can insert them by the join table like this:
var product = new Product { Name = "AA" };
var categories = new List<Category>
{
new Category{ Name = "a"},
new Category{ Name = "b"},
new Category{ Name = "c"},
};
foreach (var category in categories)
{
_context.ProductCategory.Add(
new ProductCategory
{
Product = product,
Category = category
});
}
_context.SaveChanges();
I am not sure which version you are using. with EF Core 5.o find an example at https://learn.microsoft.com/en-us/ef/core/what-is-new/ef-core-5.0/whatsnew
Models:
public class Category
{
public int CategoryId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public ICollection<Product> Products { get; set; }
}
public class Product
{
public int ProductId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public double? Price { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public bool IsApproved { get; set; }
public bool IsHome { get; set; }
public ICollection<Category> Categories { get; set; }
}
Or If you are using EE 6 or EF Core 3.1 then your models should be like:
public class Category
{
public int CategoryId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public ICollection<Product> Products { get; set; }
public ProductCategory ProductCategorie { get; set; }
}
public class Product
{
public int ProductId { get; set; }
public string Name { get; set; }
public string Url { get; set; }
public double? Price { get; set; }
public string Description { get; set; }
public string ImageUrl { get; set; }
public bool IsApproved { get; set; }
public bool IsHome { get; set; }
public ICollection<Category> Categories { get; set; }
public ProductCategory ProductCategorie { get; set; }
}
public class ProductCategory
{
public int CategoryId { get; set; }
public Category Category { get; set; }
public int ProductId { get; set; }
public Product Product { get; set; }
}
For inserting data to Many-Many tables: https://learn.microsoft.com/en-us/aspnet/core/data/ef-mvc/complex-data-model?view=aspnetcore-5.0
then please look at the section:Seed database with test data
I have problem when I try to migrate my model in EF Core 2.0.
public class Profile
{
[Key]
public Guid Id { get; set; }
public Guid UserId { get; set; }
public ExternalUser User { get; set; }
}
public class OrganizationCustomerProfile : Profile
{
public string CompanyName { get; set; }
public Address LegalAddress { get; set; }
public Address ActualAddress { get; set; }
public BusinessRequisites Requisites { get; set; }
public string President { get; set; }
public IEnumerable<ContactPerson> ContactPerson { get; set; }
}
public class PersonCustomerProfile : Profile
{
public FullName Person { get; set; }
public Address Address { get; set; }
public string PhoneNumber { get; set; }
}
public class ContactPerson
{
[Key]
public Guid Id { get; set; }
public FullName Person { get; set; }
public string Rank { get; set; }
public string Email { get; set; }
public string PhoneNumber { get; set; }
public Guid ProfileId { get; set; }
public Profile Profile { get; set; }
}
Here I want to add complex datatypes Address and BusinessRequisites, which are:
public class BusinessRequisites
{
public string OGRN { get; set; }
public string INN { get; set; }
public string KPPCode { get; set; }
public string SettlementAccount { get; set; }
public string RCBIC { get; set; }
public string CorrespondentAccount { get; set; }
public string BankName { get; set; }
}
public class Address
{
public string FullAddress { get; set; }
public float Latitude { get; set; }
public float Longtitude { get; set; }
}
Code which I use for TPH binding:
public DbSet<Profile> UserProfiles { get; set; }
public DbSet<ContactPerson> ContactPerson { get; set; }
public DbSet<OrganizationCustomerProfile> OrganizationCustomerProfile { get; set; }
...
modelBuilder.Entity<Profile>().HasKey(u => u.Id);
modelBuilder.Entity<OrganizationCustomerProfile>().OwnsOne(e => e.ActualAddress);
modelBuilder.Entity<OrganizationCustomerProfile>().OwnsOne(e => e.LegalAddress);
modelBuilder.Entity<OrganizationCustomerProfile>().OwnsOne(e => e.Requisites);
But when I try to make a migration, I get an error:
"Cannot use table 'UserProfiles' for entity type
'OrganizationCustomerProfile.ActualAddress#Address' since it has a
relationship to a derived entity type 'OrganizationCustomerProfile'.
Either point the relationship to the base type 'Profile' or map
'OrganizationCustomerProfile.ActualAddress#Address' to a different
table."
So, what the reason of this error? Is it not possible to create hierarchy inheritance in EF Core 2.0?
Thank you!
It seems like this isn't supported at the moment:
https://github.com/aspnet/EntityFrameworkCore/issues/9888
I've three entities, say Parent, Child & GrandChild. This GrandChild has got three lists(a,b & c).
How to retrive all these lists using "Include" in Entity Framework?
I can retrive one list like this: Include("Parent.Child.GrandChild.a"),
but when I add another Include like : Include("Parent.Child.GrandChild.b"), it throws an error.
How will i retrive all these lists in a single query?
My code is as follows:
objUserNew = objContaxt.ContextRegistration
.Include("listing.postlist.commentslist")
.Include("listing.postlist.taglist")
.Include("listing.postlist.knocklist")
.FirstOrDefault(x => x.id == objUser.id);
public class registration
{
public int id { get; set; }
public string firstname { get; set; }
public forgtPass forgtPass { get; set; }
public List<listing> listing { get; set; }
}
public class listing
{
public int id { get; set; }
public string address { get; set; }
public List<post> postlist { get; set; }
}
public class post
{
public int id { get; set; }
public string imgUrl { get; set; }
public List<tag> taglist { get; set; }
public List<comments> commentslist { get; set; }
public List<knoqs> knoqs { get; set; }
}
public class tag
{
public string name { get; set; }
}
public class comments
{
public int id { get; set; }
public string comment { get; set; }
public status status { get; set; }
}
public class knoqs
{
public int id { get; set; }
public virtual int registration_id { get; set; }
[ForeignKey("registration_id")] public registration registration { get; set; }
public status status { get; set; }
}
I have two models and for which I will create tables through migration and database update. My first model is named Service, and it consists of these fields:
public class Service
{
public int ServiceID { get; set; }
public string ServiceType { get; set; }
public string Category { get; set; }
public string Subcategory { get; set; }
public int Count { get; set; }
}
My second model is called Business, and it has the following fields:
public class Business
{
public int BusinessID { get; set; }
public string BusinessName { get; set; }
public string BusinessWebsite { get; set; }
public string BusinessAddress { get; set; }
public string BusinessCity { get; set; }
public string BusinessState { get; set; }
public string BusinessZip { get; set; }
public string BusinessDescription { get; set; }
[Range(0.0, 5.0)]
public int Rating { get; set; }
public DateTime LastLogIn { get; set; }
// Need to add more fields
}
The point is that I want to add Category and Subcategory fields into my Business model, but the values of Category and Subcategory fields, should be one of the values inside the Service table's values for Category and Subcategory.
Simply, I want to connect those two fields. How can I achieve it? Should I just put a Service property inside the Business model?
Break out a separate entity for "Category" and then use foreign keys:
public class Category
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
}
public class Service
{
...
public virtual Category Category { get; set; }
public virtual Category Subcategory { get; set; }
}
// Do the same when adding category/subcategory fields to `Business`
If you want to ensure that these categories are only tied to Service (and you potentially have other types of categories or something) you can always just make the entity ServiceCategory or something and only create a relationship to it from Service.
You need to separate your break out your database to store lookup table for category and a lookup table for subcategory.
Then you can create:
public class Category {
public int CategoryId { get; set; }
public string Name { get; set; }
}
public class SubCategory {
public int SubCategoryId { get; set; }
public string Name { get; set; }
}
Then change your service class to:
public class Service
{
public int ServiceID { get; set; }
public string ServiceType { get; set; }
public int CategoryId { get; set; }
public int SubcategoryId { get; set; }
public int Count { get; set; }
}
and change your Business class to:
public class Business
{
public int BusinessID { get; set; }
public string BusinessName { get; set; }
public string BusinessWebsite { get; set; }
public string BusinessAddress { get; set; }
public string BusinessCity { get; set; }
public string BusinessState { get; set; }
public string BusinessZip { get; set; }
public string BusinessDescription { get; set; }
public int CategoryId { get; set; }
public int SubCategoryId { get; set; }
[Range(0.0, 5.0)]
public int Rating { get; set; }
public DateTime LastLogIn { get; set; }
// Need to add more fields
}
I have a database with 3 tables:
Subjects
Members
Topics
Then I added the connection string to web.config and created an EF with the following classes:
namespace MySite.Models
{
public class MySiteDBModel : DbContext
{
public DbSet<Topic> Topics { get; set; }
public DbSet<Subject> Subjects { get; set; }
public DbSet<Member> Members { get; set; }
public DbSet<TopicDataModel> TopicDataModel { get; set; }
protected override void OnModelCreating(DbModelBuilder mb)
{
mb.Conventions.Remove<PluralizingTableNameConvention>();
}
}
public class Topic
{
[Key]
public int TopicID { get; set; }
public int SubID { get; set; }
public int MemberID { get; set; }
public string TDate { get; set; }
public string Title { get; set; }
public string FileName { get; set; }
public int Displays { get; set; }
public string Description { get; set; }
public virtual Subject Subject { get; set; }
public virtual Member Member { get; set; }
public virtual ICollection<TopicView> TopicView { get; set; }
}
public class Subject
{
[Key]
public int SubID { get; set; }
public string SubName { get; set; }
public virtual ICollection<Topic> Topic { get; set; }
}
public class Member
{
[Key]
public int MemberID { get; set; }
public string FLName { get; set; }
public string Email { get; set; }
public string Pwd { get; set; }
public string About { get; set; }
public string Photo { get; set; }
public virtual ICollection<Topic> Topic { get; set; }
}
public class TopicDataModel
{
[Key]
public int TopicID { get; set; }
public string SubName { get; set; }
public string FLName { get; set; }
public string TDate { get; set; }
public string Title { get; set; }
public int Displays { get; set; }
public string Description { get; set; }
}
}
Now when I am trying to query the database with the this code:
public ActionResult Index()
{
var topics = from t in db.Topics
join s in db.Subjects on t.SubID equals s.SubID
join m in db.Members on t.MemberID equals m.MemberID
select new TopicDataModel()
{
TopicID = t.TopicID,
SubName = s.SubName,
FLName = m.FLName,
TDate = t.TDate,
Title = t.Title,
Displays = t.Displays,
Description = t.Description
};
return View(topics.ToList());
}
I got this Error:
The model backing the 'MySiteDBModel' context has changed since the
database was created. Either manually delete/update the database, or
call Database.SetInitializer with an IDatabaseInitializer instance.
For example, the DropCreateDatabaseIfModelChanges strategy will
automatically delete and recreate the database, and optionally seed it
with new data.
Please help me!!!!!!
You need to set some controls on how EF is handling changes to your data model. Julie Lerman has a good blog post on Turning Off Code First Database Initialization Completely.
Also, here is a good overview - Inside Code First Database Initialization