In my Silverlight Applcication using RIA Services I have to use [Include] in the metadata file and ObjectContext.Include("WhatEver") in the DomainServiceClass file.
Can someone please explain to me why either one of them by itself is not enough?
Thanks in advance!
Apparently the Association Attribute is missing. With [Include] use [Association] (in the two related Entities, with the same name for the first parameter).
here an example
class Toto
{
public int? Id
{
get;
set;
}
[Include]
[Association("Titi_Toto", "Id", "TotoId")]
public IList<Titi> TitiList
{
get;
set;
}
}
....
class Titi
{
public int? Id
{
get;
set;
}
public int? TotoId
{
get;
set;
}
[Include]
[Association("Titi_Toto", "TotoId", "Id", IsForeighKey=True)]
public Toto TotoRef
{
get;
set;
}
}
Related
In Asp net core (3.1) Identity i want add a many to many relationship between user and TourOperators.
(The concept is that many user can follow many tour operators).
I have the tour operators class:
public class TourOperator
{
public int Id { get; set; }
public ICollection<Follow> Follows { get; set; }
}
I have extended the UserIdentity class:
public class ApplicationUser: IdentityUser
{
public ICollection<Follow> Follow { get; set; }
}
I have the Follow class:
public class Follow
{
public long Id { get; set; }
public string UserId { get; set; }
public ApplicationUser ApplicationUser { get; set; }
public int TourOperatorId { get; set; }
public TourOperator TourOperator{ get; set; }
}
After execute the migration, why in the Follow table i have 4 field instead of 3?
I have the following field:
I think that ApplicationUserId couldn't be present
Entity Framework has no way to link the UserId and ApplicationUser properties. So you either need to follow convention, whereby EF can make an educated guess. The simplest option is to rename your string property:
public string ApplicationUserId { get; set; }
Alternatively, you can configure it, for example using an attribute:
[ForeignKey("ApplicationUser"]
public string UserId { get; set; }
public ApplicationUser ApplicationUser { get; set; }
Or in the OnModelCreating method, for example:
modelBuilder.Entity<Follow>()
.WithOne(f => f.ApplicationUser)
.HasForeignKey("UserId");
I am working on Entity Framework Core Code First approach and ASP.Net Core 2.1 making 3 tables:
Person class
public class Person
{
public string Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public PeopleProfessions PeopleProfessions { get; set; }
}
Professions' class
public class Profession
{
public string Id { get; set; }
public string Name{ get; set; }
public PeopleProfessions PeopleProfessions { get; set; }
}
peopleprofessions' class
public class peopleprofessions
{
[ForeignKey("PersonId ")]
public string PersonId { get; set; }
public ICollection<Person> People { get; set; }
[ForeignKey("ProfessionId")]
public string ProfessionId{ get; set; }
public ICollection<Profession> Professions { get; set; }
}
On my Context:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<peopleprofessions>().HasKey(up => new { up.PersonId, up.ProfessionId });
}
Bearing this in mind:
People can have multiple professions.
The professions table is only for reading stored data like "Accountant".
I have doubts about how I can make table 3 only contain the foreigners and that it can meet the needs that I just mentioned.
I have tried to make the relationship appropriately but I also noticed that in tables 1 and 2 it requests both Id of the table people's professions.
I don't know if I am lost or if I am looking wrong or if there is an alternative to that situation. Thanks for any help you can give me.
You have the use of Collections on the navigation items a bit backwards. For your primary entities (Person and Profession), they should have collections, since it's one-to-many. But for the PeopleProfessions, each record is a single link to a specific entity, so no collection there just a direct object reference.
public class Person
{
public string Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public ICollection<PeopleProfessions> PeopleProfessions { get; set; }
}
public class Profession
{
public string Id { get; set; }
public string Name{ get; set; }
public ICollection<PeopleProfessions> PeopleProfessions { get; set; }
}
public class PeopleProfessions
{
public string PersonId { get; set; }
public Person Person { get; set; }
public string ProfessionId { get; set; }
public Profession Profession { get; set; }
}
You can, but don't need to specify a ForeignKey attribute because you are following EFs naming conventions(it will figure it out for you). Your OnModelCreating looks correct for the composite key.
You may want to consider removing the plural from PeopleProfessions (just call the class PeopleProfession) since one instance represents a single People-Profession relationship. I typically do this and but the navigation name in the entities remains plural, since it can represent more than one, i.e.
public ICollection<PeopleProfession> PeopleProfessions { get; set; }
I'm porting a web application to ASP.NET Core 3, and after a bit of a battle, I'm almost at the finish line. Everything seems to work, but all of a sudden my JSON data returned from the api is missing some levels.
It seems the options.JsonSerializerOptions.MaxDepth is default at 64 levels, so it can be that. Some other places where an option can be playing tricks on me?
This is the code (and a quickview of the value):
And this is the JSON I get in the browser:
So the ParticipantGroups property/collection is completely missing in the generated output.
Any ideas where this happens?
EDIT:
I've added a repo on Github that showcases the issue. Standard ASP.NET Core 3.0 solution, created from the template, with a change to the result returned from the Weatherforecast controller:
https://github.com/steentottrup/systemtextjsonissue
For now I've gone back to using Newtonsoft.Json, with the Microsoft.AspNetCore.Mvc.NewtonsoftJson package. Then when I have some time, I'll try finding out what the solution is, without Newtonsoft.Json.
The problem seems to be an error in the new version 3.0. At least it seems like an error to me.
It seems System.Text.Json will convert the class mentioned in the hierarchy, not the actual class. So if you are using an abstract class in the hierarchy, you're in trouble. The second I removed the base class, and used the actual class I'm returning, the problem goes away it seems.
So this doesn't work:
public class SurveyReportResult {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
public IEnumerable<OrganisationalUnit> OrganisationalUnits { get; set; }
}
public abstract class OrganisationalUnit {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
}
public class OrganisationalUnitWithParticipantGroups : OrganisationalUnit {
public IEnumerable<ParticipantGroup> ParticipantGroups { get; set; }
}
public class ParticipantGroup {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
}
This will only return the properties of the OrganisationalUnit class, not the additional property of the OrganisationalUnitWithParticipantGroups.
This works:
public class SurveyReportResult {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
public IEnumerable<OrganisationalUnitWithParticipantGroups> OrganisationalUnits { get; set; }
}
public class OrganisationalUnitWithParticipantGroups /*: OrganisationalUnit*/ {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
public IEnumerable<ParticipantGroup> ParticipantGroups { get; set; }
}
public class ParticipantGroup {
public Guid Id { get; set; }
public String Name { get; set; }
public Int32 MemberCount { get; set; }
}
I am a newbie in WCF. I was wondering if we can retrive properties from base interface in the REST output.
Please consider following structure. Product includes IVenueView not Venue. Is it possible to only have Venue.Id in Product JSON response?
[DataContract]
public class Product {
[DataMember]
public Guid? Id { get; set; }
[DataMember]
public string Name { get; set; }
[DataMember]
public IVenueView Venue { get; set; }
}
public interface IVenueView {
[DataMember]
Guid? Id { get; set; }
}
[DataContract]
public class Venue : IVenueView
{
[DataMember]
public Guid? Id { get; set; }
[DataMember]
public string Name { get; set; }
}
Data contracts are all about data - interfaces define behaviors, so they don't really mix up well. The data contract that you have likely will not work (because the serializer doesn't "know" about the Venue type (it only knows about IVenueView), it won't be able to serialize / deserialize instances of Product.
No it is not possible because serialization and deserialization works with the implementation (actual data) not with interfaces. Moreover for pure serialization you will have to use something like:
[DataContract]
[KnownType(typeof(Venue))]
public class Product
{
[DataMember]
public Guid? Id { get; set; }
[DataMember]
public string Name { get; set; }
[DataMember]
public IVenueView Venue { get; set; }
}
I searched a lot about how to map multiple inheritance or multiple interface implantation using EntityFramework or NHibernate But I didn't find anything useful.
I Simply want to map this structure using NHibernate:
public interface IA
{
string A { get; set; }
}
public interface IB
{
string B { get; set; }
}
public class C : IA, IB
{
string A { get; set; }
string B { get; set; }
}
As far as i know mapping this structure to a relational database means just to have foreign keys related with the interfaces primary keys, therefore the interfaces should have Keys like these:
public interface IA
{
Guid AId { get; set; }
string A { get; set; }
}
public interface IB
{
Guid BId { get; set; }
string B { get; set; }
}
public class C : IA, IB
{
public virtual Guid AId { get; set; }
public virtual Guid BId { get; set; }
public virtual string A { get; set; }
public virtual string B { get; set; }
}
But how to map this structure using NHibernate Or EntityFramework,and I don't know why multiple interface mapping is not mentioned in their documentation!
In NHibernate, you'll just map C as if the interfaces didn't exist.
You'll still be able to query on the interfaces, thanks to implicit polymorphism.
You will map it as any other class because this is not inheritance mapping. Moreover your code cannot be compiled because you must implement all properties in class C so you will get:
public interface IA
{
Guid AId { get; set; }
string A { get; set; }
}
public interface IB
{
Guid BId { get; set; }
string A { get; set; }
}
public class C : IA, IB
{
public virtual Guid AId { get; set; }
public virtual Guid BId { get; set; }
public virtual string A { get; set; }
}
Now your code can be compiled and you have class as any other. You will map AId and BId as composite key (depending on used ORM) and you are done. This is not inheritance because you have just single entity and no base enity. At least this is how it works with Entity framework.
As what I've founded it's not possible to have multiple inheritance in a relational database due to the concept and what Diego said is true in a "not interfaces get persisted scenario".