I want to replace the [Required] attribute on the Gig property of the class Notification with the following fluent api expression.
public class NotificationConfiguration : EntityTypeConfiguration<Notification>
{
public NotificationConfiguration()
{
Property(n => n.Gig).IsRequired();
}
}
If I do so, the compiler throws an error CS0453:
The type 'Gig' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'StructuralTypeConfiguration'<Notification>.Property<T>(Expression<Func<Notification, T>>)'
I cannot see the reason, why this isn't working.
Thanks!
My mistake ;-)
Gig is an object with a table representation, so this must be a navigation property to that table instead of a required field. So the code looks like this:
public class NotificationConfiguration : EntityTypeConfiguration<Notification>
{
public NotificationConfiguration()
{
HasRequired(n => n.Gig);
}
}
Related
I am new to dotnetcore so please be patient...
this ASP controller method works if I give back a list of Strings.
[HttpGet]
public List<Contract> Get()
{
return getContracts();
}
meanwhile every thing is public...it's just later where I see the error
If I return a list of very simple objects I get the warning
Inconsistent accessibility: return type 'type' is less accessible than method 'method'
the documentation for that error only shows an example for that. But how to fix it ?
Also thanks for any Link/Hint to understand the issue/rules here !
If your class is defined as:
class Contract
{
}
Then you will get the error because a class is internal by default.
A public method on a public class can't return internal types.
So we make the class public:
public class Contract
{
}
I've an abstract class:
[Configuration]
public abstract class AbstractAddon : IAddon
{
private readonly object configuration;
public AbstractAddon(object configuration)
{
this.configuration = configuration;
}
}
And several implementation of this.
I create a binding by convention as:
public class AddonsModule : Ninject.Modules.NinjectModule
{
public override void Load()
{
this.Bind(b => b.FromAssembliesMatching("*")
.SelectAllClasses()
.InheritedFrom(typeof(UIExtensibility.AbstractAddon))
.BindAllBaseClasses()
.Configure(c => c.InSingletonScope())
);
this.Bind<object>().ToProvider<ConfigurationProvider>().WhenClassHas<UIExtensibility.ConfigurationAttribute>();
}
and ConfigurationProvider is:
private class ConfigurationProvider : IProvider<object>
{
public object Create(IContext context)
{
return "configuration settings";
}
//...
}
Inside the Create method of ConfigurationProvider I thought I might be allowed to access which is the concrete class which is being requested around.
Each concrete class have an attribute PluginInformation I need in order to provide the correct configuration object. However, I don't know how to know which is the concrete class NInject is creating at the moment of the Create method provider is performed. And then, I can't get the PluginInformation attribute I need to link it and provide the correct configuration object.
How could I get access to the concrete class NInject is requesting at the moment of the object provider is performed?
The trouble was that on the first level of the IContext context parameter information, there is only the information according the Type it's providing, in my case: object type.
However IContext comes with the complete parent and plan context. So, at the point of the Create method of the provider is performed, some braches of the resolution are solved, for example: AbstractAddon. Every resolved information is on 'Context' like IContext fields. Moreover, the future steps are on 'Plan' like IContext fields.
So, in order to get the concrete type (inherited classes of AbstractAddon), I need to read the next property: context.Request.ParentContext.Plan.Type.
I have an object in C# that I want to use as a primary key in a database that auto-increments when new objects are added. The object is basically a wrapper of a ulong value that uses some bits of the value for additional hints. I want to store it as a 'pure' ulong value in a database but I would like get an automatic conversion when the value is loaded / unloaded from DB. IE, apply the 'hint' bits to the value based on the table they come from.
I went on a journey of implementing my own IUserType object based on number of examples I found online ( tons of help on this forum ).
I have an ObjectId class that acts is an object ID
class ObjectIdType: IUserType
{
private static readonly NHibernate.SqlTypes.SqlType[] SQL_TYPES = { NHibernateUtil.UInt64.SqlType };
public NHibernate.SqlTypes.SqlType[] SqlTypes
{
get { return SQL_TYPES; }
}
public Type ReturnedType
{
get { return typeof(ObjectId); }
}
...
}
I have a mapping class that looks like this:
public class ObjectTableMap()
{
Id(x => x.Id)
.Column("instance_id")
.CustomType<ObjectIdType>()
.GeneratedBy.Native();
}
At this point I get an exception at config that Id can only be an integer. I guess that makes sense but I was half expecting that having the custom type implemented, the native ulong database type would take over and work.
I've tried to go down the path of creating a custom generator but its still a bit out of my skill level so I am stumbling though it.
My question is, is it possible for me to accomplish what I am trying to do with the mapping?
I think, it is not possible, because your mapping uses the native generator for the Id. This can only be used for integral types (and GUIDs). You can try to use assigned Ids with your custom type, so you are responsible for assigning the values to your Id property.
There is another alternative: Why not set your information bits on class level, instead depending on your table? Your entities represent the tables, so you should have the same information in your entity classes. Example:
class Entity
{
protected virtual ulong InternalId { get; set; } // Mapped as Id
public virtual ulong Id // This property is not mapped
{
get
{
var retVal = InternalId;
// Flip your hint bits here based on class information
return retVal;
}
}
}
You could also turn InternalId into a public property and make the setter protected.
I use ASP.NET WCF to return .NET objects in JSON format through jquery calls.
When I changed my .NET classes to serializable, which I expose through methods in my WCF class, the objects property names suddenly changed from:
Name to _Name.
So all code in my javascript classes where I access json objects is wrong.
Why do the properties have a underscore prefix now?
And how do I change it back without removing the serializable attribute on the classes?
Thanks.
Christian
When you say that you "changed the class to serializable", does it mean you added the [Serializable] attribute on them? If this is the case: classes marked with that attribute have all of their fields serialized (no properties). In the example below, this class doesn't have any attributes, and it does have a parameter-less constructor, so it's considered a "POCO" (plain-old CLR object) type. POCO types have their public members (fields or properties) serialized. If you decorate it with [Serializable], then it will fall into the serializable rule.
Why do you need to mark your type with [Serializable]? If you really need to do that (for some legacy serializer), you can also decorate your type with [DataContract] and [DataMember] attributes, which are honored by the WCF serializer. You'd add [DataContract] on the type, and [DataMember] on the properties which you want serialized.
public class Person
{
private string _Name;
private int _Age;
public string Name {
get { return this._Name; }
set { this._Name = value; }
}
public string Age {
get { return this._Age; }
set { this._Age = value; }
}
}
I have a class which I would like to map as a component onto any table which contains it:
public class Time
{
public int Hours { get; set; }
public int Minutes { get; set; }
public int Seconds { get; set; }
}
I would like to store this class as a bigint in the database - the same as how TimeSpan is stored but my class has completely different behaviour so I decided to create my own.
I'm using FLH's automapper and have this class set as a component (other classes have Time as a property). I've got as far as creating an override but am not sure how to go about mapping it:
I gave it a try this way:
public class TimeMappingOverride : IAutoMappingOverride<Time>
{
public void Override(AutoMapping<Time> mapping)
{
mapping.Map(x => x.ToTimeSpan());
mapping.IgnoreProperty(x => x.Hours);
mapping.IgnoreProperty(x => x.Minutes);
mapping.IgnoreProperty(x => x.Seconds);
}
}
But got this error:
Unable to cast object of type 'System.Linq.Expressions.UnaryExpression' to type 'System.Linq.Expressions.MethodCallExpression'.
How should I go about this?
Details of components can be found here: http://wiki.fluentnhibernate.org/Fluent_mapping#Components
But first of all, you can't map a method.
Assuming you change ToTimeSpan() to a property AsTimeSpan, there are two ways to do it, only the harder of which will work for you because you are using automapping:
Create a ComponentMap<Time> -- once done, your existing mapping will just work. This is not compatible with automapping.
Declare the component mapping inline:
mapping.Component(x => x.AsTimeSpan, component => {
component.Map(Hours);
component.Map(Minutes);
component.Map(Seconds);
});
You'll have to do this every time, though.
Of course, this doesn't address "I would like to store this class as bigint…"
Are you saying you want to persist it as seconds only? If so, scratch everything at the top and again you have two options:
Implement NHibernate IUserType (ugh)
Create a private property or field that stores the value as seconds only, and wire only this up to NHibernate. The getters and setters of the pubic properties will have to convert to/from seconds.
I personally haven't worked with AutoMappings yet, but my suggestion would be to look into NHibernate's IUserType to change how a type is being persisted. I believe that's a cleaner way of defining your custom mapping of Time <-> bigint.
Reading the code above, Map(x => x.ToTimeSpan()) will not work as you cannot embed application-to-database transformation code into your mappings. Even if that would be possible, the declaration misses the transformation from the database to the application. A IUserType, on the other hand, can do custom transformations in the NullSafeGet and NullSafeSet methods.