EDIT: The original problem statement included only one reference to the Owned entity. But it turns out that the problem I encountered happens with multiple references to the Owned entity AND some funky fluent configuration code. I've rewritten this problem statement to explain the details of the problem I ran into.
I started with one EF Core entity, which references an Owned entity:
public class InvoiceItem
{
public SubscriptionPlanDetails SubscriptionPlan { get; set; }
}
[Owned]
public class SubscriptionPlanDetails
{
public string PlanName { get; set; } // Plan name
public decimal Price { get; set; } // Price (USD)
}
When I enter the command "add-migration" in the VS Package Manager Console, scaffolder complains:
No type was specified for the decimal column 'Price' on entity type 'SubscriptionPlanDetails'.
So I added some fluent API configuration:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<SubscriptionPlanDetails>()
.Property(p => p.Price)
.HasColumnType("money");
}
Problem solved... or so I thought. Then I added another entity with a reference to the same Owned entity:
public class Account
{
public int Id { get; set; }
public SubscriptionPlanDetails SubscriptionPlan { get; set; }
// Navigation properties
public virtual ICollection<InvoiceItem> InvoiceItems { get; set; }
}
So, each account has one subscription plan (Account.SubscriptionPlan), and each account has multiple InvoiceItems, each of which contains all of the details of the subscription plan that was in effect at the time the invoice item was created (Account.InvoiceItems.SubscriptionPlan).
Now, when I try to add a migration, it complains
No type was specified for the decimal column 'Price' on entity type 'InvoiceItem.SubscriptionPlan#SubscriptionPlanDetails'.
So I added fluent API code to configure the Owned property. But I neglected to remove the previous code. So, my configuration code looked like this:
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
// This should have been removed!
builder.Entity<SubscriptionPlanDetails>()
.Property(p => p.Price)
.HasColumnType("money");
builder.Entity<Account>().OwnsOne(m => m.SubscriptionPlan)
.Property(p => p.Price)
.HasColumnType("money");
builder.Entity<InvoiceItem>().OwnsOne(m => m.SubscriptionPlan)
.Property(p => p.Price)
.HasColumnType("money");
}
Attempting to add a migration gets me a NullReferenceException.
If I comment out the offending call to builder.Entity<SubscriptionPlanDetails>() then it works as expected!
I think the best way to override this decimal warning is to annotate the price with the following:
[Column(TypeName = "decimal(18,2)")]
public decimal Price { get; set; }
You can also use the type "money" instead of "decimal(18,2)"
Related
I have this model:
public class Book
{
public int Id { get; set; }
public string Name { get; set; }
public Uri Link { get; set; }
}
I added it to fluent-api using the following code:
builder.Entity<Book>(entity => {
entity.HasKey(b => b.Id);
});
when I run this:
add-migration InitialMigration -context MyAppContext
then I get:
No suitable constructor found for entity type 'Uri'. The following parameters could not be bound to properties of the entity: 'uriString', 'uriString', 'dontEscape', 'baseUri', 'relativeUri', 'dontEscape', 'uriString', 'uriKind', 'baseUri', 'relativeUri', 'serializationInfo', 'streamingContext', 'baseUri', 'relativeUri', 'flags', 'uriParser', 'uri'.
You can't persist a Uri directly to the database, as there's no associated SQL type for that. You need to use a string instead. If you're using a view model (as you should be), your view model can have the Uri, and then you simply need to get the string representation during your mapping to your actual entity type.
You can also simply utilize EF Core's value conversion (available in 2.1+). See the docs for more detail. Essentially, in your fluent config:
.HasConversion(
v => v.ToString(),
v => new Uri(v));
A value conversion can be added to your DbContext to convert the type used when reading from or writing to the database. This is done by overriding the OnModelCreating method.
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder
.Entity<Book>()
.Property(e => e.Link)
.HasConversion(v => v.ToString(), v => new Uri(v));
}
I have a simple POCO type, say something like
public class OwnedEntity {
public string stringProperty { get; set; }
public decimal decimalProperty { get; set; }
public bool boolProperty { get; set; }
public int intProperty { get; set; }
}
and an actual entity with an OwnedEntity reference
public class SomeEntity {
public string Id { get; set; }
public OwnedEntity OwnedEntity { get; set; }
}
I set up the relationship like described in the documentation using EF Core's Fluent API:
protected override void OnModelCreating (ModelBuilder builder) {
base.OnModelCreating (builder);
builder.Entity<SomeEntity> ().OwnsOne (e => e.OwnedEntity);
}
I can't find anything on how to define default-values for all the properties of OwnedEntity. I tried to initialize the properties like this:
public class OwnedEntity {
public string stringProperty { get; set; } = "initial"
public decimal decimalProperty { get; set; } = -1M;
public bool boolProperty { get; set; } = false;
public int intProperty { get; set; } = -1;
}
but with no effect. Same goes with the [DefaultValueAttribute] (but that was to expect since it's explicitly mentioned).
There's a bit of information on how to handle initial values for regular entities:
modelBuilder.Entity<SomeOtherEntity>()
.Property(e => e.SomeIntProperty)
.HasDefaultValue(3);
But since I'm facing an Owned Entity Type, I can't access the type via Entity<T>.
Is there a way of doing what I'm looking for?
Some things worth mentioning:
I have a solid amount of specific entities where most of them are using the OwnsOne relation
Declaring all OwnedEntity-properties in a base class is not an option since not all the entities have those properties
I`m using EF Core 2.0.3 and ASP.NET Core MVC 2.0.4
Edit:
Originally, I wanted to have newly created SomeEntity instances to come with preset properties for all of the 'embedded' SomeEntity.OwnedEntity properties.
But looking at how my associated controller works, it all makes sense... I have the following methods for the 'Create' operation:
[HttpGet]
public IActionResult Create () {
return View (nameof (Create));
}
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create (SomeEntity model) {
context.Add (model);
await context.SaveChangesAsync ();
// redirect etc.
}
Which means that no object is created for the [HttGet] overload of Create and all the HTML inputs linked to properties (via asp-for) are initially empty. Okay. So I guess the proper way of doing this is to manually create a new instance of SomeEntity and pass it to the Create view like this:
[HttpGet]
public IActionResult Create () {
return View (nameof (Create), new SomeEntity());
}
Is this the right approach then or are there some more things to keep in mind?
Assuming you understand what EF Core Default Values are for, and just looking for equivalent of Entity<T>().Property(...) equivalent.
The owned entities are always configured for each owner type by using the ReferenceOwnershipBuilder<TEntity,TRelatedEntity> class methods. To access this class you either use the result of OwnsOne method, or use the OwnsOne overload taking second argument of type Action<ReferenceOwnershipBuilder<TEntity,TRelatedEntity>>.
For instance, using the second approach:
builder.Entity<SomeEntity>().OwnsOne(e => e.OwnedEntity, ob =>
{
ob.Property(e => e.stringProperty)
.HasDefaultValue("initial");
ob.Property(e => e.decimalProperty)
.HasDefaultValue(-1M);
// etc.
});
In my ASP.NET Core Web API application, I am having trouble relating entities in Entity Framework Core. When I send a GET request to the Controller through Postman all of the Model's records are returned, but the navigation properties for their related entities come back null. Unfortunately, there are no errors or exceptions thrown either. The (simplified) code is as follows:
//DBContext
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Location>();
modelBuilder.Entity<Person>(entity =>
{
entity.HasOne(p => p.Location)
.WithMany(l => l.People)
.HasForeignKey(p => p.Location_ID);
});
}
//Person Model
public partial class Person
{
[Key]
public int People_ID { get; set; }
public int? Location_ID { get; set; }
public Location Location { get; set; }
}
//Location Model
public partial class Location
{
public Location()
{
People = new HashSet<Person>();
}
[Key]
public int Location_ID { get; set; }
public ICollection<Person> People { get; set; }
}
As far as I understand it, because I dictated the two Models are related using the Fluent API in the OnModelCreating method, the properties should be 'Eagerly Loaded'. Why is this not happening?
As far as I understand it, because I dictated the two Models are related using the Fluent API in the OnModelCreating method, the properties should be 'Eagerly Loaded'
You understand it wrong. The Eager Loading behavior is not implicit (like lazy loading), you have to explicitly request it using Include / ThenInclude methods.
For instance, the following will return the Person entities with Location property populated:
return db.Set<Person>().Include(p => p.Location);
I would like to set up a many to many relationship in ASP.NET MVC4.
The goal is to extend the default UserProfile class with a list of Timeline objects, which belong to the user.
A Timeline could be shared by multiple users, so the Timeline class should have an list of UserProfile objects aswell.
Timeline class:
namespace MvcApplication1.Models
{
public class Timeline
{
public int Id { get; set; }
public string Name { get; set; }
public string Color { get; set; }
public List<UserProfile> Users { get; set; }
}
public class TimelineContext : DbContext
{
public DbSet<Timeline> Timelines { get; set; }
public DbSet<UserProfile> UserProfiles { get; set; }
// Added the following because I saw it on:
// http://www.codeproject.com/Tips/548945/Generating-Many-to-Many-Relation-in-MVC4-using-Ent
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<Timeline>()
.HasMany(c => c.Users)
.WithMany(s => s.Timelines)
.Map(mc =>
{
mc.ToTable("TimelineOwners");
mc.MapLeftKey("TimelineId");
mc.MapRightKey("UserId");
});
}
}
}
UserProfile class (default class with an added property):
public class UsersContext : DbContext
{
public UsersContext()
: base("DefaultConnection")
{
}
public DbSet<UserProfile> UserProfiles { get; set; }
public DbSet<Timeline> Timelines { get; set; }
// Added the following because I saw it on:
// http://www.codeproject.com/Tips/548945/Generating-Many-to-Many-Relation-in-MVC4-using-Ent
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.Entity<UserProfile>()
.HasMany(c => c.Timelines)
.WithMany(s => s.Users)
.Map (mc =>
{
mc.ToTable("TimelineOwners");
mc.MapLeftKey("UserId");
mc.MapRightKey("TimelineId");
});
}
}
[Table("UserProfile")]
public class UserProfile
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int UserId { get; set; }
public string UserName { get; set; }
public List<Timeline> Timelines { get; set; }
}
I have a connection table with foreign keys:
When creating an instance of Timeline, the Users list is null:
Timeline timeline = db.Timelines.Find(id); // timeline.Users = null
Can somebody please enlighten me, how should I set this up working?
I'm totally new to ASP.NET MVC4.
Edit 1: I understand I should not extend UserProfile but create another class to store users. Once the many-to-many relationship works, I will refactor and go into that direction.
But first I would like to know why is it not working.
Edit 2:
The double context also caused problems, two databases were created for the two contexts and the pure join table was empty in one of them.
I suggest that you work through this article about the options how you can load navigation properties with Entity Framework. This is very basic knowledge which is important for every kind of relationship, not only many-to-many relationships.
Looking at that article you will find then that this line...
Timeline timeline = db.Timelines.Find(id);
...does not load any related entities. So, it's expected that timeline.Users is null, even if the entities are related in the database.
If you want to load the Users you can use eager loading:
Timeline timeline = db.Timelines.Include(t => t.Users)
.SingleOrDefault(t => t.Id == id);
This is a single database query. Or to enable lazy loading you have to mark your navigation properties as virtual:
public virtual List<UserProfile> Users { get; set; }
//...
public virtual List<Timeline> Timelines { get; set; }
You can then use your original code:
Timeline timeline = db.Timelines.Find(id); // first query
var users = timeline.Users; // second query
This will run two separate queries. The second is performed as soon as you access the navigation property for the first time.
BTW: Is there a reason why you have two context classes - TimelineContext and UsersContext? "Normally" you need only one context.
I'm not a fan of messing with the working of the internal userprofile. I would suggest creating your own user class, linking it to the simplemembershipprovider and adding functionality there. At max you'll extend the accountclasses a little to add more fields to register with, but that's about it.
Follow this extremely handy guide to get things working and let me know if you encounter an error.
I've just installed the new Entity Framework 4.1 NuGet package, thus replacing the EFCodeFirst package as per NuGet intructions and this article of Scott Hanselman.
Now, imagine the following model:
public class User
{
[Key]
public string UserName { get; set; }
// whatever
}
public class UserThing
{
public int ID { get; set; }
public virtual User User { get; set; }
// whatever
}
The last EFCodeFirst release generated a foreign key in the UserThing table called UserUserName.
After installing the new release and running I get the following error:
Invalid column name 'User_UserName'
Which of course means that the new release has a different FK naming strategy. This is consistent among all other tables and columns: whatever FK EFCodeFirst named AnyOldForeignKeyID EF 4.1 wants to call AnyOldForeignKey_ID (note the underscore).
I don't mind naming the FK's with an underscore, but in this case it means having to either unnecessarily throw away the database and recreate it or unnecessarily renaming al FK's.
Does any one know why the FK naming convention has changed and whether it can be configured without using the Fluent API?
Unfortunately, one of the things that didn't make it to this release is the ability to add custom conventions in Code First:
http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-release-candidate-available.aspx
If you don't want to use the fluent API to configure the column name (which I don't blame you), then most straight forward way to do it is probably using sp_rename.
Why don't you do the following?
public class User
{
[Key]
public string UserName { get; set; }
// whatever
}
public class UserThing
{
public int ID { get; set; }
public string UserUserName { get; set; }
[ForeignKey("UserUserName")]
public virtual User User { get; set; }
// whatever
}
Or, if you don't want to add the UserUserName property to UserThing, then use the fluent API, like so:
// class User same as in question
// class UserThing same as in question
public class MyContext : DbContext
{
public MyContext()
: base("MyCeDb") { }
public DbSet<User> Users { get; set; }
public DbSet<UserThing> UserThings { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<UserThing>()
.HasOptional(ut => ut.User) // See if HasRequired fits your model better
.WithMany().Map(u => u.MapKey("UserUserName"));
}
}