I'm trying to add some info to the data result whether the user has read or write access to the entity.
Lets assume I have this entity:
public class Foo
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Access> AccessRights { get; set; }
}
Where AccessRights holds the user id and if they have read/write access.
Currently I just $expand AccessRights and calculate if the user has read/write access in the frontend. However I'd like this calculated property to be added to the result.
Example json result:
{
id: 1,
name: "foo",
hasReadAccess: true,
hasWriteAccess: true
}
Is it possible to do this? Keep in mind that HasRead/WriteAccess doesn't exist on the model nor should it.
You need to split your model in two: a data access model (what you get from the data access layer) and a data transfer model (what you send as a response).
Assuming your current Foo class as the data access model, you simply need to define another class FooResponse (or whatever name suits you) as follows.
public class FooResponse
{
public int Id { get; set; }
public string Name { get; set; }
public bool HasReadAccess { get; set; }
public bool HasWriteAccess { get; set; }
}
Then define a transformation function that maps from Foo instances to FooResponse instances. AutoMapper is a good tool for the job.
Related
I have a class which is exposed by an ASP.NET OData V4 API:
public class Person
{
public int TitleId { get; set; }
//Other properties like First Name, Last Name, DoB and so on...
}
The TitleId property is an Id that maps to a persons Title (Mr, Miss, Mrs so on) which is located at a different OData endpoint address.
Is there any way of providing metadata to let the consumer of the API know where the lookup values are for this property or should I approach this in a different way?
Edit: I am looking for a way to provide metadata to inform the consumer of the location of the lookup values. There is no database involved, this is a mapping layer over a much more complicated API.
if you have the Class of Title and have that in the Database this is working:
public class Title
{
public int Id { get; set; }
public string TitleName { get; set; }
}
then use this that as Virtual in your current model.
[ForeignKey("TitleId")]
public virtual Title { get; set; }
public int TitleId{ get; set; }
I'm sure it does the mapping.
then just address them to Title.TitleName.
I have added computed fields(Active and CreditsLeft) directly into my CodeFirst entity class. Is it good idea to add computed field logic inside CF Entity class?
public class User : Entity
{
public User()
{
Id = Helper.GetRandomInt(9);
DateStamp = DateTime.UtcNow;
TimeZone = TimeZoneInfo.Utc.Id;
}
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int Id { get; set; }
[Required]
[MaxLength(50)]
public string Email { get; set; }
[Required]
[MaxLength(50)]
public string Password { get; set; }
[MaxLength(50)]
public string FirstName { get; set; }
[MaxLength(50)]
public string LastName { get; set; }
[Required]
public DateTime DateStamp { get; set; }
public virtual ICollection<Order> Orders { get; set; }
public virtual ICollection<Statistic> Statistics { get; set; }
public virtual ICollection<Notification> Notifications { get; set; }
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public bool Active
{
get
{
return Orders.Any(c => c.Active && (c.TransactionType == TransactionType.Order || c.TransactionType == TransactionType.Subscription));
}
}
[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public int CreditsLeft
{
get
{
return Orders.Sum(p => p.Credits != null ? p.Credits.Value : 0);
}
}
}
Is it good idea to add computed field logic inside CF Entity class?
Sure, you can do this, but there are a few things you must take care of.
First, the attribute for a property that is computed by business logic is not [DatabaseGenerated(DatabaseGeneratedOption.Computed)], because this indicates that the value is computed in the database (as in a computed column). You should mark the property by the [NotMapped] attribute. This tells Entity Framework to ignore the property in database mapping.
Second, since both properties use Orders, you must make sure that the orders are loaded or can be lazy loaded when either property is accessed. So you may want to load Users with an Include statement (Include(user => user.Orders)). Or else you must ensure that the context is still alive when Active or CreditsLeft is accessed.
Third, you can't address the properties directly in an EF LINQ query, as in
db.Users.Select(u => u.Active);
because EF will throw an exception that it doesn't know Active. You can address the properties only on materialized user objects in memory.
Note: Technoligies in use are ASP.Net MVC 3, Entity, SQL Server Management Studio
Problem?
It seems that when I run, the context as: public class DatabaseInit : DropCreateDatabaseAlways<LocationAppContext>
That it creates the database, but my service assignments table has an extra foreign key called
ServiceAssignment_Service when it shouldn't.
My service assignment model is as such:
namespace LocationApp.Models
{
public class ServiceAssignment
{
public int id { get; set; }
public int locationID { get; set; }
public int ServiceID { get; set; }
public virtual Location Location { get; set; }
public virtual ServiceAssignment Service { get; set;}
}
}
and the service model is as such:
namespace LocationApp.Models
{
public class Service
{
public Service()
{
this.ServiceAssignments = new HashSet<ServiceAssignment>();
}
public int id { get; set; }
public string name { get; set; }
public string description { get; set; }
public bool active { get; set; }
public string icon { get; set; }
public virtual ICollection<ServiceAssignment> ServiceAssignments { get; set; }
}
}
with that said, the relation ship is simple:
service assignments have many location id's and service id's.
why is this extra foriegn key being generated? the curent keys, that should e there is:
PK: Main PK for the table
FK 1: Location_ServiceAssignment
FK 2: Service_ServiceAssignment
Those are their, how ever this third one is baffling....
The second part is: If a location of id 2 has a service id of 2,3,6,7 How do I get all service id's returned, such that I can pass the object to a service query to get all information on the service based on the ID?
Update:
Context Class:
namespace LocationApp.DAL
{
public class LocationAppContext : DbContext
{
public DbSet<Content> Contents { get; set; }
public DbSet<Location> Locations { get; set; }
public DbSet<ServiceAssignment> ServiceAssignments { get; set; }
public DbSet<Service> Services { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
modelBuilder.Entity<Location>().HasMany(sa => sa.ServiceAssignments);
modelBuilder.Entity<Service>().HasMany(sa => sa.ServiceAssignments);
}
}
}
I think you have to tell EF that Service.ServiceAssignments is the inverse navigation property of ServiceAssignment.Service and that Location.ServiceAssignments is the inverse of ServiceAssignment.Location. Right now with your mapping you only specify that Location or Service has many ServiceAssignments. EF will consider the navigation properties in ServiceAssignment as the ends of separate relationships.
Try instead the mapping:
modelBuilder.Entity<Location>()
.HasMany(l => l.ServiceAssignments)
.WithRequired(sa => sa.Location)
.HasForeignKey(sa => sa.LocationID);
modelBuilder.Entity<Service>()
.HasMany(s => s.ServiceAssignments)
.WithRequired(sa => sa.Service)
.HasForeignKey(sa => sa.ServiceID);
You can probably remove this mapping altogether as an alternative because EF should detect the right relationships by convention.
So, use either no mapping (=mapping by convention) or the full mapping (=specifying both ends of the relationships). Just the 50%-mapping you have used is likely the problem.
Sorry about the title; couldn't think of a better one.
Any way, I'm accessing an associated property in my view like so:
#Model.Company.CompanyName // No problems here...
The model is a viewmodel mapped to an EF POCO. The Model has several properties associated to the Company table. Only one of the properties in the model share the same name as the PK in the Company table. All the other properties reference the same table:
public class MyModelClass
{
public int Id { get; set; }
public int CompanyId { get; set; }
public int AnotherCompanyId { get; set; } // References CompanyId
public int AndAnotherCompanyId { get; set; } // References CompanyId
public Company Company { get; set; }
}
public class Company
{
public int CompanyId { get; set; }
public string CompanyName { get; set; }
public string Address { get; set; }
}
I'm obviously missing something here.
How can I get the names of the other companies in my Model?
Any help is greatly appreciated.
The model is a viewmodel mapped to an EF POCO
I think you are confusing the notion of a view model. A view model is a class that is specifically designed to meet the requirements of your view. So if in your view you need to display the company name and not the company id then your view model should directly contain a CompanyName property. Or a reference to another view model (CompanyViewModel) which contains the name directly. It is then the responsibility of your controller action to query your domain models (EF entities) and aggregate them into a single view model tat will contain all the necessary information that the view requires.
Here's how a typical view model might look like:
public class MyViewModel
{
public CompanyViewModel Company { get; set; }
public CompanyViewModel AnotherCompany { get; set; }
public CompanyViewModel AndAnotherCompany { get; set; }
}
public class CompanyViewModel
{
public string Name { get; set; }
}
Where the data comes from in this view model is not important. You could have the Company property populated from your EF stuff, the AnotherCompany property populated from a XML file and AndAnotherCompany from WCF.
Setup
Using MVC 3 + Code First
Here are my classes
public class Member
{
[Key]
public Guid ID { get; set; }
[Required]
public String Email { get; set; }
[Required]
public String FirstName { get; set; }
[Required]
public String LastName { get; set; }
public String Sex { get; set; }
public String Password { get; set; }
public String PasswordSalt { get; set; }
public DateTime RegisterDate { get; set; }
public DateTime LastOnline { get; set; }
public String SecurityQuestion { get; set; }
public String SecurityAnswer { get; set; }
public virtual ICollection<FamilyMember> Families { get; set; }
public virtual ICollection<Relationship> Relationships { get; set; }
}
public class Relationship
{
[Key]
public Guid ID { get; set; }
[ForeignKey("Member1")]
public Guid Member1ID { get; set; }
[ForeignKey("Member2")]
public Guid Member2ID { get; set; }
public Guid RelationshipTypeID { get; set; }
public virtual RelationshipType RelationshipType { get; set; }
public virtual Member Member1 { get; set; }
public virtual Member Member2 { get; set; }
}
Here is the problem
The database table "Relationship" is being created with the following columns:
ID, Member1ID, Member2ID, RelationshipTypeID, Member_ID
Why is it creating the Member_ID column?
I've seen this post in which the user has the same type of setup, but I am unsure of how to define the InverseProperty correctly. I tried using fluent API calls but from what I can tell they will not work here since I have two foreign keys referring to the same table.
Any help would be appreciated!
Member_ID is the foreign key column which EF created for the navigation property Member.Relationships. It belongs to a third association from Member.Relationships refering to an end endpoint which is not exposed in your Relationship entity. This relationship has nothing to do with the other two relationships from Relationship.Member1 and Relationship.Member2 which also both have an endpoint not exposed in Member.
I guess, this is not what you want. You need always pairs of endpoints in two entities to create an association. One endpoint is always a navigation property. The second endpoint can also be a navigation property but it is not required, you can omit the second navigation property.
Now, what is not possible, is to associate two navigation properties (Member1 and Member2) in one entity with one navigation property (Relationships) in the other entity. That is what you are trying to do apparently.
I assume that your Member.Relationships property is supposed to express that the member is either Member1 or Member2 in the relationship, or that it participates in the relationship, no matter if as Member1 or Member2.
Unfortunately you cannot express this in the model appropriately. You have to introduce something like RelationsshipsAsMember1 and RelationsshipsAsMember2 and for these two collection you can use the InverseProperty attribute as shown in the other question. In addition you can add a helper property which concats the two collections. But this is not a mapped property but readonly:
public class Member
{
// ...
[InverseProperty("Member1")]
public virtual ICollection<Relationship> RelationshipsAsMember1 { get; set; }
[InverseProperty("Member2")]
public virtual ICollection<Relationship> RelationshipsAsMember2 { get; set; }
public IEnumerable<Relationship> AllRelationships
{
get { return RelationshipsAsMember1.Concat(RelationshipsAsMember2); }
}
}
Accessing AllRelationships will cause two queries and roundtrips to the database (with lazy loading) to load both collections first before they get concatenated in memory.
With this mapping the Member_ID column will disappear and you will only get the two expected foreign key columns Member1ID, Member2ID because now you have only two associations and not three anymore.
You could also think about if you need the Relationships collection in the Member entity at all. As said, navigation properties on both sides are not required. If you rarely need to navigate from a member to its relationships you could fetch the relationships also with queries on the Relationship set, like so:
var relationships = context.Relationships
.Where(r => r.Member1ID == givenMemberID || r.Member2ID == givenMemberID)
.ToList();
...or...
var relationships = context.Relationships
.Where(r => r.Member1ID == givenMemberID)
.Concat(context.Relationships
.Where(r => r.Member2ID == givenMemberID)
.ToList();
This would give you all relationships the member with ID = givenMemberID participates in without the need of a navigation collection on the Member entity.