I created two classes:
public class A {
public int Id { get; set; }
public ICollection<B> Bs { get; set; }
}
public class B {
public ICollection<C> C1s { get; set; }
public ICollection<C> C2s { get; set; }
}
then I tried to fetch them with ThenInclude method:
var result = context.As //public DbSet<A> As { get; set; }
.Include(a => a.Bs)
.ThenInclude(b => b.C1s)
.Include(a => a.Bs)
.ThenInclude(b => b.C2s)
.SingleOrDefaultAsync(a => a.Id.Equals(id)); //id is given
return await result;
But unfortunately both C1s and C2s collections are empty.
How to retrieve C entities which are related to B one?
I replaced .ThenInclude() methods with
.Include("Points.MasterPoints")
.Include("Points.SlavePoints")
That solved my issue.
Related
I have different roles and each user can have multiple roles. Each role is connected to customer record in different way, e.g. a business analyst has many-to-many relation to project and each customer has many projects; whereas a customer record can have only one project manager associated to it.
public class Customer
{
public CustomerProjectManager ProjectManager { get; set; }
public ICollection<Project> Projects{ get; set; }
...
}
public class Project
{
public ICollection<ProjectBusinessAnalyst> BusinessAnalysts { get; set; }
public ICollection<ProjectDeveloper> ProjectDevelopers { get; set; }
...
}
public class ProjectDeveloper
{
public int Id { get; set; }
public Project Project{ get; set; }
public int ProjectId { get; set; }
public string DeveloperId { get; set; }
public string DeveloperEmail { get; set; }
public string DeveloperName { get; set; }
}
public class CustomerProjectManager
{
public int Id { get; set; }
public ICollection<Customer> Customers { get; set; }
public string ProjectManagerId { get; set; }
public string ProjectManagerEmail { get; set; }
public string ProjectManagerName { get; set; }
public CustomerProjectManager()
{
Customers = new List<Customer>();
}
}
I need to fetch customer records on basis of roles. To explain further, I need to combine multiple customer lists fetched on the basis of different roles assigned to a single user. I am unable to form right linq query.
I have a sample query, mentioned below, which sometimes returns the right records but if I have a new user and no customers are assigned to this user, the query returns all existing customers. Its important for me that all the combination and filtration is done in Iqueryable
Please help!
public async Task<List<Customer>> FetchCustomers(string userId, List<string> userRoles, string userEmail)
{
if (userRoles.Contains("Admin"))
{
customer = _context.Customers;
}
else if (userRoles.Contains("Project Manager") ||
userRoles.Contains("Business Analyst") ||
userRoles.Contains("Developer"))
{
if (userRoles.Contains("Project Manager"))
{
customers = customers.Where(c => c.ProjectManager.ProjectManagerId == userId
|| c.Projects.Any(op =>
op.ProjectsCompleted.Any(assignee =>
assignee.UserId == userId)));
}
if (userRoles.Contains("Business Analyst"))
{
var allPossibleCustomers = _context.Customers.Where(c =>
c.Projects.Any(op => op.BusinessAnalysts.Any(ba => ba.BusinessAnalystId == userId)));
customers = customers?.Union(allPossibleCustomers) ?? allPossibleCustomers;
}
if (userRoles.Contains(Roles.Developer.GetDescription()))
{
var allPossibleCustomers = _context.Customers.Where(c =>
c.Projects.Any(op => op.PREDevDevelopersAssigned.Any(ba => ba.DeveloperId == userId)));
customers = customers?.Union(allPossibleCustomers) ?? allPossibleCustomers;
}
}
var listData = await PagingList<Customer>.CreatePageAsync(customers, page, limit);
return listData;
}
Apparently I was trying to return the wrong list. The linq query is correct.
I have the classes below:
public class User
{
public Guid Id { get; set; }
public string Name { get; set; }
}
public class ParentEntity
{
public Guid Id { get; set; }
public string SomeProperty { get; set; }
public ICollection<ChildEntity> ChildEntities { get; set; }
}
public class ChildEntity
{
public Guid Id { get; set; }
public int Vote { get; set; }
public Guid UserId { get; set; }
}
public class ReturnedParentDto
{
public Guid Id { get; set; }
public string SomeProperty { get; set; }
public int Vote { get; set; }
}
I want to be able to return a full list of ParenEntities, but take an Id of the User class (UserClassId), then filter the ParentEntity's ICollection where UserUid = UserClassId, so only 1 ChildEntity is always returned. Then I would want to extract a specific field from that returned ChildEntity and merge it with the ParentEntity fields. The end result should be like the ReturnedParentDto.
I want to do it in the style like
ParentEntities.Include(v => v.ChildEntities).ToList()
That seems to be possible in EF Core 5, but my project is in 3.1.
You can do this as below
Approach 1:
var result = result = parentEntities.Include(x => x.ChildEntities.Where(y => y.UserId == userId))
.Select(x => new ReturnedParentDto {
Id = x.Id,
SomeProperty = x.SomeProperty,
Vote = x.ChildEntities.FirstOrDefault()?.Vote // userId is the variable here
});
Approach 2:
var result = parentEntities.Select(x =>
new ReturnedParentDto {
Id = x.Id,
SomeProperty = x.SomeProperty,
Vote = x.ChildEntities.FirstOrDefault(y => y.UserId == userId)?.Vote // userId is the variable here
});
I using Ef Core 2.2.and I have an Entity It has Self-Relation And Each Entity Might have a List Of Entities
This Is My Entity
public class CourseGroup
{
public int ID { get; set; }
public string Title { get; set; }
public bool IsDeleted { get; set; }
//Foreign key
public int? ParentId { get; set; }
//Navigations Property
public CourseGroup ParentCourseGroup { get; set; }
//Relatons => Self Relation
public ICollection<CourseGroup> Groups { get; set; }
}
And This Is My Configurations
class CourseGroupConfig : IEntityTypeConfiguration<CourseGroup>
{
public void Configure(Microsoft.EntityFrameworkCore.Metadata.Builders.EntityTypeBuilder<CourseGroup> builder)
{
builder.HasKey(c => c.Id);
builder.Property(c => c.Id).ValueGeneratedOnAdd();
builder.Property(c => c.Title).HasMaxLength(60);
//Relations
builder.HasOne(c => c.ParentCourseGroup).WithMany(c => c.Groups).HasForeignKey(c => c.ParentId);
}
}
And I Wanna get All Entities With Sub Entities. How Can I Write This Query With Linq?
Please Do me a favor to Write This Query
I'm having two classes - author and blogpost:
public class Author
{
public Author()
{
Blogposts = new HashSet<Blogpost>();
}
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Blogpost> Blogposts { get; set; }
}
and
public class Blogpost
{
public Blogpost()
{
}
// Properties
public int Id { get; set; }
public string Text { get; set; }
public int AuthorId { get; set; }
public Author Author { get; set; }
}
Using EF7 (beta4), I'm connecting them the following way:
public partial class MyDbContext : DbContext
{
public virtual DbSet<Author> Author { get; set; }
public virtual DbSet<Blogpost> Blogpost { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Author>(entity =>
{
entity.Property(e => e.Id)
.ForSqlServer().UseIdentity();
});
modelBuilder.Entity<Blogpost>(entity =>
{
entity.Property(e => e.Id)
.ForSqlServer().UseIdentity();
});
modelBuilder.Entity<Blogpost>(entity =>
{
entity.Reference<Author>(d => d.Author).InverseCollection(p => p.Blogposts).ForeignKey(d => d.AuthorId);
});
}
}
When I access a blogpost Db.Blogpost.First(x => x.Id == id) I retrieve the Blogpost object - however, the .Author property is null. Also, when retrieving any Author object, it's .Blogposts collection is empty.
I understand the EF7 has neither implemented eager-loading nor lazy-loading yet. But how would I then retrieve/assign any objects referenced via foreign key?
EF 7 has implemented eager loading.
Use .Include
var post = context.Blogpost.First(); // post.Author will be null
var post = context.Blogpost.Include(b => b.Author).First(); // post.Author will be loaded
For more information on working with collections, see the answer to this question: How to work with collections
I'm using Entity Framework 4 CTP5 Code First and I have a model along the lines of:
public class User {
public int UserId { get; set; }
public string Email { get; set; }
public ICollection<Customer> TaggedCustomers { get; set; }
}
public class Customer {
public int CustomerId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public ICollection<User> TaggedBy { get; set; }
}
There is a many to many relationship where a User can 'tag' a Customer and a Customer can be 'tagged' by many users. I have a working DbContext and I can query customers using
var customers = DbContext.Customers.Include(c => c.TaggedBy);
But each customer will have all users that have tagged the customer. How do I restrict the TaggedBy collection to just result with a specifed UserId?
I've tried along the lines of DbContext.Customers.Include(c => c.TaggedBy.Select(x => x.Id == userId)); but that throws an error.
EF Feature CTP5: Fluent API Samples - ADO.NET team blog - Site Home - MSDN Blogs
modelBuilder.Entity<Product>()
.HasMany(p => p.Tags)
.WithMany(t => t.Products)
.Map(m =>
{
m.MapLeftKey(p => p.ProductId, "CustomFkToProductId");
m.MapRightKey(t => t.TagId, "CustomFkToTagId");
});
Code First Mapping Changes in CTP5 - ADO.NET team blog - Site Home - MSDN Blogs
modelBuilder.Entity<Product>()
.HasMany(p => p.SoldAt)
.WithMany(s => s.Products)
.Map(mc => {
mc.ToTable("ProductsAtStores");
mc.MapLeftKey(p => p.Id, "ProductId");
mc.MapRightKey(s => s.Id, "StoreId");
});
Mark your collections as virtual and then you can easily do:
public class User
{
public int UserId { get; set; }
public string Email { get; set; }
public virtual ICollection<Customer> TaggedCustomers { get; set; }
}
public class Customer
{
public int CustomerId { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public virtual ICollection<User> TaggedBy { get; set; }
}
using(var context = new MyDbContext())
{
var user = context.Users.Single(o => o.UserId == 0);
var customers = user.TaggedCustomers;
}
Results in much cleaner code in my opinion.