Reading and writing an INI file from ASP.NET 2.0

Introduction

I needed a way to quickly & easily store settings in an INI file. There are tons of classes out there, but most seemed to be overkill for what I was trying to do. So I put this class together. It works well for me. I hope someone else will find it valuable.

Here's my example INI, note the [eof] required at the end:

; web application settings

[email]

emailAdminFrom = "user@domain.com"
someOtherSetting = "some value"

[eof]

Here's the class:

Imports Microsoft.VisualBasic
Imports System.IO

Public Class ini
    Public Shared Function read(ByVal iniFile As String, ByVal searchKey As String)

        Dim lenSS As Integer = Len(searchKey)
        Dim locQ As Integer
        Dim newStr As String

        Using sr As StreamReader = _
          New StreamReader(HttpContext.Current.Server.MapPath(iniFile))
            Dim line As String
            ' loop until end of file
            Do
                line = sr.ReadLine()
                ' check each line for a key match
                If Left(line, lenSS) = searchKey Then
                    ' match found, now parse out value
                    ' find the first quote mark
                    locQ = InStr(line, """")
                    ' now create the value
                    newStr = Mid(line, (locQ + 1), ((Len(line) - locQ) - 1))
                    ' return the value
                    Return newStr
                    line = Nothing
                End If
            Loop Until line Is Nothing
            sr.Close()
        End Using
        Return "error"
    End Function

    Public Shared Function write(ByVal iniFile As String, _
           ByVal writeKey As String, ByVal writeValue As String)

        ' temp file #1
        Dim iniTempFile As String = "/tempsettings_del.ini"
        ' temp file #2
        Dim iniTempOrigFile As String = "/tempsettingsorig_del.ini"
        ' length of search string
        Dim lenSS As Integer = Len(writeKey)
        ' eof? t/f
        Dim boolEof As Boolean
        ' string to search for at eof
        Dim strEof As String = "[eof]"
        ' server.mappath to all files used
        Dim iniMappedFile As String = _
           HttpContext.Current.Server.MapPath(iniFile)
        Dim iniMappedTempFile As String = _
           HttpContext.Current.Server.MapPath(iniTempFile)
        Dim iniMappedTempOrigFile As String = _
           HttpContext.Current.Server.MapPath(iniTempOrigFile)

        ' setup file to output to
        Dim sw As StreamWriter = New StreamWriter(iniMappedTempFile)

        ' process overview:
        ' 1. read each line of orig ini file
        ' 2. check for match, if no match, write to temp file
        ' 3. if match, write new value
        ' 4. write rest of orig ini file

        ' new value to write
        Dim strNewValue = writeKey & " = """ & writeValue & """"

        Using sr As StreamReader = New StreamReader(iniMappedFile)
            Dim line As String
            ' loop until end of file
            Do
                line = sr.ReadLine()
                ' first check for eof so we don't write extra blank lines
                If Left(line, 5) = strEof Then boolEof = True

                ' check each line for a key match
                If Left(line, lenSS) = writeKey Then
                    ' match found, write new value to temp file
                    sw.WriteLine(strNewValue)
                Else
                    ' are we at the enf of the file?
                    If boolEof = True Then
                        sw.WriteLine(strEof)
                        ' break out of loop
                        Exit Do
                    End If
                    ' match not found, write line to temp file
                    sw.WriteLine(line)
                End If
            Loop Until line Is Nothing
            sr.Close()
        End Using
        sw.Close()

        ' 1 / 3. move orig file to temp file in case 2nd move fails
        File.Move(iniMappedFile, iniMappedTempOrigFile)

        ' 2 / 3. move temp file to orig file
        File.Move(iniMappedTempFile, iniMappedFile)

        ' 3 / 3. delete renamed, now temp orig file
        File.Delete(iniMappedTempOrigFile)

        ' done
        Return ""
    End Function
End Class

Here's an example usage to retrieve a value:

' path to ini
Dim iniSettings as string = "/settings.ini"

' key to read from
Dim strKey as string = "emailAdminFrom"

' read email address
Dim strEmail = ini.read(iniSettings, strKey)

Here's an example usage to write a value:

' path to ini
Dim iniSettings as string = "/settings.ini"

' key to write to
Dim strKey as string = "emailAdminFrom"

' new value to write
Dim strNewValue as string = "newuseremail@domain.com"

' write email address
ini.write(iniSettings, strKey, strNewValue)