How to retrieve absolute physical/ virtual path inside vb class

recently my friends ask me how to write a code to retrieve absolute path from vb class for his asp.net application. the problem is server.mappath function cannot be used inside vb class so he ask for alternative.

so here's the solution that i think is good for sharing with everyone:

' import declarative
imports system.web

private strPath as string = Web.Hosting.HostingEnvironment.MapPath("~/App_Data/Dashboard.mdb")
Private sqlconn As New OleDbConnection("Provider=Microsoft.jet.oledb.4.0; data source=" & strPath & ";Jet OLEDB:Database Password=Dashboard; ")

the function HostingEnvironment.MapPath used to retrieve the physical / virtual path in the server. for more info about the HostingEnvironment classes you can go here:
Hosting Environment Class

that's it, hope it useful for everyone..

Enabling file download with asp.net

here's the code for downloading file from web server to client:

// create temporary file
dim strTemp as string = System.IO.Path.GetTempFileName

// here your process for example generating excel file

// here's the code for file download
Response.ContentType = "application/octet-stream"
Response.AddHeader("Content-Disposition", _
"attachment;filename=" & strFileName & ".xls")
Response.Flush()
Response.WriteFile(strTemp)
Response.End

* if your are using asp.net ajax update panel with this code, it will cause problem to the update panel.

the solution can be found here:
Ajax file download and iframe

Problem with parameterized Query in asp.net and Microsoft Access

today i face a problem with my asp.net application. the update query i write doesn't update value inside database and there is no error state while running the application. i also try to test run the query inside microsoft access query builder, it works just fine. so after trying and error for a few minute i find a simple solution or simply rules(maybe)

Here the sample code:

dim strQuery as string
dim olecmd as oledbcommand
dim oleparam as oledbparameter

strQuery = "update dsb_mthinp set dsb_mthinp_value=@value where dsb_inpfield_code=@inpcode and dsb_mthinp_month=@month and dsb_mthinp_year=@year"

olecmd = new oledbcommand(strQuery, dbconn)

oleparam = new oledbparameter
oleparam.parametername = "@inpcode"
oleparam.value=getInputcode
olecmd.parameter.add(oleparam)

oleparam = new oledbparameter
oleparam.parametername = "@month"
oleparam.value=getInputcode
olecmd.parameter.add(oleparam)

oleparam = new oledbparameter
oleparam.parametername = "@year"
oleparam.value=getInputcode
olecmd.parameter.add(oleparam)

oleparam = new oledbparameter
oleparam.parametername = "@value"
oleparam.value=getInputcode
olecmd.parameter.add(oleparam)

dbconn.open()
olecmd.executeNonQuery
dbconn.close()

if you can see in the sample code that i marked as bold and italic, i'm writting the parameter value in the wrong order, means i start "@inpcode" as the first parameter rather than "@value". this lead to wrong parameter value during executing the sql statement. means value for:

"@value" = getInpcode
"@inpcode" = getmonth
"@month" = getYear
"@Year" = getValue

basically i really don't understand why this problem happen, it is because i already provide the parameter name, means the value should follow the parameter name. but perhaps it just a rule that i missed read somewhere in .net documentation.

so the solution is simple, put the first parameter "@value" before the "@inpcode" parameter, or in other words follow the order of parameter you write in your sql statement, then your query will run as you wish...

this solution applied to :
asp.net 2.0 and microsoft access 2000 database

that's all... and happy coding