I am trying to learn a new framework (i think) and i have got to a stage where im not sure whats going on.
So i created a class and a Metadata class. My assumption was that i would have had access to the properties but of course i havent.
I read this link http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.metadatatypeattribute.aspx and followed the example. All seems correct but how do i get access to the properties in the class? I was going to add them to the Partial class but since the example on MSDN doesnt do this, i think i may have missed the point and where does the metadata come into play?
<MetadataType(GetType(CustomerMetadata))> _
Partial Public Class Customer
End Class
Public Class CustomerMetadata
Public Property Cid As Integer = 0
Public Property Name As String = String.Empty
End Class
Thanks
Related
I created a simple solution with an EDMX file that possess one table Sport with 2 field IdSport and Label. I would like to insert a record in DB with an object inherited of the Sport object created by EF.
Public Class Index
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim aSport As New TestSport()
Using ctx As New FormationEntities
ctx.AddObject("Sport", aSport)
ctx.SaveChanges()
End Using
End Sub
End Class
Public Class TestSport
Inherits Sport
End Class
With an Sport object it work but not with TestSport. I need the inherited class for adding some properties and others functionnalities, but when I save it, I would like to save only the property possessed by the parent object Sport.
Error message:
Mapping and metadata information could not be found for EntityType
I know that the usual way is to use partial class but on my project, the EDMX file is in another project, so the only solution I see is to use an inherited class.
What am I doing wrong? How to fix my problem? Is it exist a better way to do it?
Thanks.
On searching through gooogle I found the following link, where a very similar scenario is discussed:
Deriving from classes generated by Entity Framework in C#
Although there is one post marked as answer, but the second answer is equally relevant.
Hope this helps.
Entity Framework appears to use a kind of reflection during the saving of your entities, and is probably why your inheritances do not work. One way you could still add functionality to your enties(albeit only functions) is using Extension methods: http://msdn.microsoft.com/en-us//library/bb383977.aspx
But if it is more than just some functions you need to add, consider a more structural solution. Having part of your object in a data layer and part of that same object in an upper layer is not a good separation of responsibilities.
Instead of having part of the class in your data project(I assume), and part of it in another project, consider creating one 'Logics class' in your project which wraps around your entity and adds functionality that way. You could for example do this by exposing the entity directly:
public class SportLogic
{
private Sport _sport;
public Sport Sport { get { return _sport; } }
public string SomeNewProperty { get; set; }
public void DoStuff() {};
}
Or the way I use where the logics object is acting as an actual logical wrapper around the entity. It is cleaner because it obfuscates the entity entirely: any calling code wil not need knowledge of your entity(Sport) object.
public class SportLogic
{
private Sport _sport;
public string SportProperty { get { return _sport.SportProperty; } set { _sport.SportProperty = value; } }
public string SomeNewProperty { get; set; }
public void DoStuff() {};
}
I need to bind request parameters to an instance of the following Java class (getters and setters omitted):
public class ShippingHouse {
private String name;
private String description;
private List<ShippingRule> shippingRules = new ArrayList<ShippingRule>();
}
public class ShippingRule {
private ShippingHouse shippingHouse;
private String name
}
Notice that there is a 1:N relationship between ShippingHouse and ShippingRule, but each ShippingRule also has a reference to the ShippingHouse thaat owns it.
If these were Grails command/domain classes, I would bind them with request parameters
name=foo&description=bar&shippingRules[0].name=sr0&shippingRules[1].name=sr1
But it doesn't seem like this will set the reference to the owning ShippingHouse within each ShippingRule. Is there a way I can bind this automatically, or must I write the code myself?
Don,
You will need to write code to do it yourself using BindUsing or some other approach. The binder doesn't (and shouldn't) assume anything about back references from a parent to a child. If these were GORM entities and the relationship was explicit, that is different, but in your case the binder should not assume that shippingHouse property in the ShippingRule class has anything to do with the shippingRules property in the ShippingHouse class.
Also note that lucke84 said that your "private" is implicit. Make sure you understand what that means if you are going to remove them. If you remove them the compiler is going to generate public getter and setter methods for those properties, which may or may not be what you want.
If you want to implement a 1:N relationship between the two classes, you should use the right grails approach. Something like this:
class ShippingHouse {
String name
String description
static hasMany = [shippingRules: ShippingRule]
}
class ShippingRule {
String name
static belongsTo = [shippingHouse: ShippingHouse]
}
Please note that semicolons are useless and the "private" declaration on class fields is implicit.
I have been sharing database variables using the following code:
Namespace DataAccessVariables
Public Class Vars
Public Shared s As String
Public Shared con As String = WebConfigurationManager.ConnectionStrings("Dev").ToString()
Public Shared c As New SqlConnection(con)
Public Shared x As New SqlCommand(s, c)
End Class
End Namespace
I then import this to my project like this:
Imports DataAccessVariables.Vars
When I check the site with FXCop, I get this message:
Error, Certainty 90, for StaticHolderTypesShouldNotHaveConstructors
{
Target : DBVars (IntrospectionTargetType)
Resolution : "Remove the public constructors from 'Vars'."
Help : http://msdn2.microsoft.com/library/ms182169(VS.90).aspx (String)
Category : Microsoft.Design (String)
CheckId : CA1053 (String)
RuleFile : Design Rules (String)
Info : "Instances of types that define only static members
do not need to be created. Many compilers will automatically
add a public default constructor if no constructor
is specified. To prevent this, adding an empty private
constructor may be required."
Created : 2010/04/20 01:25:16 PM (DateTime)
LastSeen : 2010/04/21 07:17:46 AM (DateTime)
Status : Active (MessageStatus)
Fix Category : Breaking (FixCategories)
}
If I remove the 'Public Shared' from the declarations, then the variables are not picked up in my pages. Can anyone show me the correct way of sharing them?
Thanks a lot,
Phil.
This error isn't telling you to remove the Public Shared variables. Instead it's letting you know that it is possible to create a new instance of your Vars class, even though it includes only Shared members. To resolve the issue, define a private constructor:
Private Sub New()
End Sub
This will prevent any code creating an instance of the Vars class outside of the class itself.
Is that the only code in your class?
Also, you should not create a global (static) SqlConnection. Simply create the SqlConnection and SqlCommand objects on-demand. Connection pooling will ensure that only one physical database connection is made at a time.
The way you've got it here, it's not thread-safe (if two people make a request at the same time, for example, things are going to get really screwy).
I have an asp.net nTier application. The data access layer is a strongly typed DataSet consisting of multiple DataTables with DataAdapters. When the user logs in, they choose which database to connect to (from a table in the membership database). I need to pass the selected connection string into the DataSet object which will remain the same for that users until they log in again.
I'm thinking that the answer might be to create a partial class of the DataSet object where I can pass the connection string into the constructor. Im not sure how to go about this though.
Cheers
You could do this with a partial class.
Assuming your typed dataset is called HurrDurr:
public partial class HurrDurr
{
public HurrDurr(string connex)
{
this._connection = new global::System.Data.SqlClient.SqlConnection();
this._connection.ConnectionString = connex;
}
}
_connection is only initialized if it is null the first time the Connection internal property is accessed.
Finally got to the bottom of this. In a new module I created a partial class to the table adapter which is where I needed to change the connection string, one mistake I was making originally was not specifying the correct namespace.
Below is the partial class I created which allowed me to dynamically change the connection string of one of my table adapters for a table called tblOptions:
Namespace ds1TableAdapters
Partial Public Class tblOptionsTableAdapter
Sub ChangeConnString(ByVal newConn As String)
Me._connection.ConnectionString = newConn
End Sub
End Class
End Namespace
Thanks for the help Will, it got me going in the right direction.
am trying to implement fluent nhibernate in MVC project...there were no build errors... but when i run the project i get this exception
System.Xml.Schema.XmlSchemaValidationException: The element 'class' in namespace 'urn:nhibernate-mapping-2.2' has incomplete content. List of possible elements expected: 'meta, subselect, cache, synchronize, comment, tuplizer, id, composite-id' in namespace 'urn:nhibernate-mapping-2.2'.
have no idea what am doing wrong here... the following is the code for opening session factory...
Private Function CreateSessionFactory() As ISessionFactory
Dim sessionFactoryObject As ISessionFactory
sessionFactoryObject = Fluently.Configure().Database(FluentNHibernate.Cfg.Db.MsSqlConfiguration.MsSql2005.ConnectionString("Data Source=.\sqlexpress;Initial Catalog=Designs;User ID=sa;Password=root")).Mappings(Function(x) x.FluentMappings.Add(GetType(DesignMap))).BuildSessionFactory()
Return sessionFactoryObject
End Function
this is really driving me nuts....thanks in advance...:)
update-the mappings
the design table map
Public Class DesignMap
Inherits ClassMap(Of Design)
Public Sub DesignMap()
Table("DesignList")
Id(Function(x) x.DesignId)
Map(Function(x) x.DesignType)
References(Function(x) x.Designer, "DesignerId")
End Sub
End Class
the designer table map
Public Class DesignerMap
Inherits ClassMap(Of Designer)
Public Sub DesignerMap()
Table("DesignerList")
Id(Function(x) x.DesignerId)
Map(Function(x) x.DesignerName)
Map(Function(x) x.DesignerCompany)
HasMany(Function(x) x.DesignersDesigns)
End Sub
End Class
new edit-- the entity property looks like this
Public Overridable Property Name() As String
Get
Return _name
End Get
Protected Set(ByVal value As String)
_name = value
End Set
End Property
am i going the right way..?
I'm not quite sure as the mappings seem ok. I can see one error tough, you have only mapped one of your classes:
.Mappings(Function(x) x.FluentMappings.Add(GetType(DesignMap)))
That should not cause this type of error tough. If you add both your mappings and call the method .ExportTo(#"C:\your\export\path") you will get the actual xml mappings. This way it's easier to see the error. You can do that like this:
.Mappings(Function(x) x.FluentMappings.Add(GetType(DesignMap)).Add(GetType(DesignerMap
).ExportTo(#"C:\your\export\path"))
You can also use the method AddFromAssemblyOf (or some other. There is a few choices) if you don't want to add the mappings one by one.
Try exporting the mappings and see if you can find any error. Or you can post the xml mappings and someone else might find something.
There are several things that can cause this. When using automappings, you will get this if you incorrectly specify the assemblies and namespaces to look in. Other things (more likely in your case) that could cause it, are entity properties that aren't marked as public virtual, having an entity constructor with arguments, but neglecting to make a default constructor, or inheriting your entities from a base class.
I would probably first check to make sure all of your entity properties are "public virtual".
found the problem...the constructor for the map was wrong...it should be like this...
Public Class DesignMap
Inherits ClassMap(Of Design)
Public Sub New()
Table("DesignList")
Id(Function(x) x.DesignId)
Map(Function(x) x.DesignType)
References(Function(x) x.Designer, "DesignerId")
End Sub
End Class
problems of working in both C# and vb.net at the same time i guess..!!
and "Matthew Talbert" was correct...making all the properties Overrideable is important..
thanks guys...:)