Question

I have a class that add extra information about a column for linq2sql (see code below)

right now, I have to explicitly tell what column I want that info on, how would you put that code with a loop on every column in every table from a dbml file?

I was doing my test on a very very small DB, now I have to implement it on a much more bigger database and I really don’t want to do it manually for every tables/columns

it will take hours.

how it’s being used:

Partial Class Contact ''contact is a table inside a dbml file.

Private _ContactIDColumn As ExtraColumnInfo
Private _ContactNameColumn As ExtraColumnInfo
Private _ContactEmailColumn As ExtraColumnInfo
Private _ContactTypeIDColumn As ExtraColumnInfo

Private Sub OnCreated()
    initColumnInfo()
End Sub

Private Sub initColumnInfo()
    Dim prop As PropertyInfo

    prop = Me.GetType.GetProperty("ContactID")
    _ContactIDColumn = New ExtraColumnInfo(DirectCast(prop.GetCustomAttributes(GetType(ColumnAttribute), False)(0), ColumnAttribute))

    prop = Me.GetType.GetProperty("ContactName")
    _ContactNameColumn = New ExtraColumnInfo(DirectCast(prop.GetCustomAttributes(GetType(ColumnAttribute), False)(0), ColumnAttribute))

    prop = Me.GetType.GetProperty("ContactEmail")
    _ContactEmailColumn = New ExtraColumnInfo(DirectCast(prop.GetCustomAttributes(GetType(ColumnAttribute), False)(0), ColumnAttribute))

    prop = Me.GetType.GetProperty("ContactTypeID")
    _ContactTypeIDColumn = New ExtraColumnInfo(DirectCast(prop.GetCustomAttributes(GetType(ColumnAttribute), False)(0), ColumnAttribute))

    prop = Nothing
End Sub

Public ReadOnly Property ContactIDColumn() As ExtraColumnInfo
    Get
        Return _ContactIDColumn
    End Get
End Property

Public ReadOnly Property ContactNameColumn() As ExtraColumnInfo
    Get
        Return _ContactNameColumn
    End Get
End Property

Public ReadOnly Property ContactEmailColumn() As ExtraColumnInfo
    Get
        Return _ContactEmailColumn
    End Get
End Property

Public ReadOnly Property ContactTypeIDColumn() As ExtraColumnInfo
    Get
        Return _ContactTypeIDColumn
    End Get
End Property
End Class

what is ExtraColumnInfo:

Public Class ExtraColumnInfo

Private _column As ColumnAttribute
Private _MaxLength As Nullable(Of Integer)
Private _Precision As Nullable(Of Integer)
Private _Scale As Nullable(Of Integer)
Private _IsIdentity As Boolean
Private _IsUniqueIdentifier As Boolean

Sub New(ByVal column As ColumnAttribute)
    Dim match As Match

    _column = column

    Match = Regex.Match(DBType, "^.*\((\d+)\).*$", RegexOptions.Compiled Or RegexOptions.IgnoreCase)
    _MaxLength = If(match.Success, Convert.ToInt32(match.Groups(1).Value), Nothing)

    match = Regex.Match(DBType, "^.*\((\d+),(\d+)\).*$", RegexOptions.Compiled Or RegexOptions.IgnoreCase)
    _Precision = If(Match.Success, Convert.ToInt32(Match.Groups(1).Value), Nothing)

    match = Regex.Match(DBType, "^.*\((\d+),(\d+)\).*$", RegexOptions.Compiled Or RegexOptions.IgnoreCase)
    _Scale = If(match.Success, Convert.ToInt32(match.Groups(2).Value), Nothing)

    match = Regex.Match(DBType, "^.*\bIDENTITY\b.*$", RegexOptions.Compiled Or RegexOptions.IgnoreCase)
    _IsIdentity = match.Success

    match = Regex.Match(DBType, "^.*\bUniqueIdentifier\b.*$", RegexOptions.Compiled Or RegexOptions.IgnoreCase)
    _IsUniqueIdentifier = match.Success
End Sub

'others available information
'AutoSync
'Expression
'IsVersion
'Name
'Storage
'TypeId
'UpdateCheck
'maybe more

Public ReadOnly Property CanBeNull() As Boolean
    Get
        Return _column.CanBeNull
    End Get
End Property

Public ReadOnly Property IsDbGenerated() As Boolean
    Get
        Return _column.IsDbGenerated
    End Get
End Property

Public ReadOnly Property IsPrimaryKey() As Boolean
    Get
        Return _column.IsPrimaryKey
    End Get
End Property

Public ReadOnly Property DBType() As String
    Get
        Return _column.DbType
    End Get
End Property

Public ReadOnly Property MaxLength() As System.Nullable(Of Integer)
    Get
        Return _MaxLength
    End Get
End Property

Public ReadOnly Property Precision() As System.Nullable(Of Integer)
    Get
        Return _Precision
    End Get
End Property

Public ReadOnly Property Scale() As System.Nullable(Of Integer)
    Get
        Return _Scale
    End Get
End Property

Public ReadOnly Property IsIdentity() As Boolean
    Get
        Return _IsIdentity
    End Get
End Property

Public ReadOnly Property IsUniqueIdentifier() As Boolean
    Get
        Return _IsUniqueIdentifier
    End Get
End Property
End Class

Answer 1

I took the T4 template and modified it a little to automatically put inside the generated class the column information,

in the import I added

    Imports System.Reflection
    Imports System.Text.RegularExpressions

at line 228, added these line:

    <# foreach(Column column in class1.Columns) {#>
    Private _<#=column.Member#>Column As ExtraColumnInfo
    Public ReadOnly Property <#=column.Member#>Column() As ExtraColumnInfo
        Get
            Return _<#=column.Member#>Column
        End Get
    End Property

    <#              }#>

at line 298 I added

    Dim prop As PropertyInfo
    <# foreach(Column column in class1.Columns) {#>
    prop = Me.GetType.GetProperty("<#=column.Member#>")
    _<#=column.Member#>Column = New ExtraColumnInfo(DirectCast(prop.GetCustomAttributes(GetType(ColumnAttribute), False)(0), ColumnAttribute))
    <#      }#>

at the end of the file, I added my own class