Question LInq To SQL ( map file question)

[duckkiller53]

Linq to SQL using datacontext and a map file.

Could someone help me with the following question. I have been reading "Linq in Action" by Fabrice Marquerie, in particular Linq to SQL and mapping objects via an xml map file. The question is this, is there a way to use the map files without explicitly using a Namespace ( ie: a prebuilt .dll that is referenced within a project ) for the <Type> attribute to see my object class.

for example: I have a small Lia.mdf data base with an 'Authors' table. The project creates a map file and then uses that map to instantiate a datacontext. What I had hoped to do was just add the objects to my project, ie: an Author.vb class etc, and then have everything work. The problem I experience was that the project class was obviously recognized when instantiating the class etc but the reference via the map file could not be established for the type.

ie: <Table Name="Author" Member="Author">
<Type Name="Author">

The only way I could get this to work ( and from what I read on the net ) was to create a class library project (named 'Sample' with the object, build it and then reference the Sample.dll in my Linq project.

ie: <Table Name="Author" Member="Author">
<Type Name="Sample.Author">

The above works but is there a way to do this and just use normal object classes within your project. I really want to understand this because I feel the power of being able to have normal objects within a project and then use both Linq to SQL and possibly a normal datalayer would be extremely powerful.

Note: The author of "Linq in Action" did it the same way I did. He used SQLMetal to create the map but he compiled a .dll and then referenced it in his project.

Any help would be greatly appreciated. ( I have referenced the code I used below )

Thanks You

***********Sample**************

Public Sub XmlMapping()
Dim map As XmlMappingSource = _ XmlMappingSource.FromXml(System.IO.File.ReadAllText("AuthorMap.xml"))

Dim dataContext As New DataContext(connString, map)
Dim authors = dataContext.GetTable(Of Sample.Author)()

'Do something with the collection ...

Sub Main()

XmlMapping)
Console.ReadLine()

End Sub

*************Map File******************

<?xml version="1.0" encoding="utf-8" ?>
<Database Name="Lia" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007">
<Table Name="Author" Member="Author">
<Type Name="Sample.Author">
<Column Name="ID" Member="ID" Storage="_ID" DbType="UniqueIdentifier NOT NULL" IsPrimaryKey="true" UpdateCheck="Never" />
<Column Name="LastName" Member="LastName" Storage="_LastName" DbType="VarChar(50) NOT NULL" CanBeNull="false" UpdateCheck="Never" />
<Column Name="FirstName" Member="FirstName" Storage="_FirstName" DbType="VarChar(30) NOT NULL" CanBeNull="false" UpdateCheck="Never" />
<Column Name="WebSite" Member="WebSite" Storage="_WebSite" DbType="VarChar(200)" UpdateCheck="Never" />
<Column Name="TimeStamp" Member="TimeStamp" Storage="_TimeStamp" DbType="rowversion NOT NULL" CanBeNull="false" IsDbGenerated="true" IsVersion="true" UpdateCheck="Never" AutoSync="Always" />
<Association Name="FK_BookAuthor_Author" Member="BookAuthor" Storage="_BookAuthor" ThisKey="ID" OtherKey="Author" DeleteRule="NO ACTION" />
</Type>
</Table>
</Database>

*************Object Class***************

Public Class Author
Private _Id As Guid
Public Property ID() As System.Guid
Get
Return _Id
End Get
Set(ByVal value As System.Guid)
_Id = value
End Set
End Property

Private _LastName As String
Public Property LastName() As String
Get
Return _LastName
End Get
Set(ByVal value As String)
_LastName = value
End Set
End Property

Private _FirstName As String
Public Property FirstName() As String
Get
Return _FirstName
End Get
Set(ByVal value As String)
_FirstName = value
End Set
End Property

Private _WebSite As String
Public Property WebSite() As String
Get
Return _WebSite
End Get
Set(ByVal value As String)
_WebSite = value
End Set
End Property

Private _TimeStamp As Byte()
Public Property TimeStamp() As Byte()
Get
Return _TimeStamp
End Get
Set(ByVal value As Byte())
_TimeStamp = value
End Set
End Property
End Class

 

[duckkiller53]

One last thing: This is the error message I would get before I created the .dll namespace

"Mapping Problem: Cannot find type 'Author' from mapping."

 

[JohnH]

All assemblies have a namespace, also your client application. Have a look in project properties, Application tab, there you see what "Root namespace" your project has, for example "WindowsApplication1". So if you add a Author class to your project the namespace qualified name will be WindowsApplication1.Author.
I haven't actually tested this map, but common sense indicates it should be this simple.

Are you sure the namespace is needed? I saw a few examples on web that didn't use namespace for type also.

 

[duckkiller53]

The Book I'm reading stated that you don't need the namespace, But when I googled the error I found others stating that you need the namespace. That's how I got the idea for the .dll.


Scooby

 

[JohnH]

Well, assembly is assembly and namespace is namespace, one isn't different from another in that perspective. It is possible though that you nested the class when you were experimenting.

 

[duckkiller53]

Could someone help, I have been testing using linq to sql with map files. So far the only way I have been able to get this to work is to use fully qualify the namespace.object in the <Type> attribute of my map file.

ie:

This does not work!!!!
---------------------
<Table Name="dbo.Categories" Member="Categories">
<Type Name="Categories">

This works
----------
<Table Name="dbo.Categories" Member="Categories">
<Type Name="NorthWindMetal.Categories">

Thanks

Scooby