Dot-Net Programming Tips: August 2010

Monday, August 23, 2010

hiii

Saturday, August 21, 2010

Tuesday, August 17, 2010

HTTPException was unhandled by User Code?

HTTPException was unhandled by User Code?

Error executing child request for ~/page.aspx.

Ans: if page.aspx not exists in your current directory or renamed, so check the name.

Microsoft JScript runtime error?

Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.

Details: Error parsing near '

<!DOCTYPE html P'.

Ans: Server.Transfer or Response.write wont work in Ajax enabled pages.

Thursday, August 12, 2010

Sample LINQ Queries

DBDataContext objeDC =new DBDataContext();

1. How to check whether the UserID exist in the table using LINQ?

UserMst objUserMst =null;
objUserMst= objeDC.UserMsts.SingleOrDefault(Rec => Rec.UserMstID == "sample");
if(objUserMst !=null)
//exists
else
// Not exists

PwdHistory objHistory = new PwdHistory();
objHistory.UserName = "Sample";
objHistory.UserPwd = FormsAuthentication.HashPasswordForStoringInConfigFile("password", "MD5");
objeDC.PwdHistories.InsertOnSubmit(objHistory);
objeDC.SubmitChanges();

FormsAuthentication.HashPasswordForStoringInConfigFile("password", "MD5");

4. use Transaction in LINQ (Roll and Commit)

DBTransaction objDBTrans=null;
objDBTrans = objeDC.Connection.BeginTransaction();
objeDC.Transaction = objDBTrans ;
try
{
       PwdHistory objHistory = new PwdHistory();
       objHistory.UserName = "Sample";
       objHistory.UserPwd = FormsAuthentication.HashPasswordForStoringInConfigFile("password", "MD5");
       objeDC.PwdHistories.InsertOnSubmit(objHistory);
       objeDC.SubmitChanges();
       objDBTrans.Commit();
}
catch(Exception ex)
{
       objDBTrans.RollBack();
}

5. Simple where condition using LINQ

var Result = from objLogin in objeDC.LoginLogs
where objLogin.UserMstID == strLoginId && objLogin.LoginEventID == "02"
select objLogin;

objUserMst = objeDC.UserMsts.SingleOrDefault(Rec => Rec.UserMstID == "sample");
if (objUserMst != null)
{
objUserMst.eInsInd = true;
objeDC.SubmitChanges();
}

var Result = from objUserGroup in objeDC.UserGroups
select objUserGroup;
DropdownList1.DataTextField = "Dsc";
DropdownList1.DataValueField = "UserGroupID";
DropdownList1.DataSource = Result;
DropdownList1.DataBind();

var Result = from objNewsMast in objeDC.NewsMasts
orderby objNewsMast.TimeStamp
select objNewsMast;
gvNewsImage.DataSource = Result;
gvNewsImage.DataBind();

var Result = from objMenu in objeDC.Menus
select new
{
          MenuID = objMenu.MenuID.ToString().Contains(".aspx") == true?objMenu.MenuID :
           string.Empty ,
           Dsc = objMenu.Dsc,
};

UserGroups objUserGrp = null;
objUserGrp = objeDC.UserGroups.SingleOrDefault(Rec => Rec.UserGroupID == "stringval");
if (objUserGrp != null)
{
objeDC.UserGroups.DeleteOnSubmit(objUserGrp);
objeDC.SubmitChanges();
}

11. Delete multiple records based on condition using LINQ?

objeDC.MenuAccesses.DeleteAllOnSubmit(objeDC.MenuAccesses.Where(Tmpr => Tmpr.MenuID == strMenuID));
objeDC.SubmitChanges();

ex.. Convert Datetime column (MM/dd/YYYY) to dd/MM/yyyy

var objResult = from objTemp in
( from objNewsMast in objeDC.NewsMasts
   select new
   {
       Date = objNewsMast.TimeStamp,
      Title = objNewsMast.Title,
    }).ToList()
select new
{
    Date = objTemp.Date.ToString("dd/MM/yyyy"),
   Title = objTemp.Title,
});

13. convert LINQ Results to DataTable

var ResultProgram = from objProgram in objeDC.Programs
select objProgram;
DataTable dtProgram = LINQToDataTable(ResultProgram);

14. LINQ to DataTable

public DataTable LINQToDataTable<T>(IEnumerable<T> varlist)
{
      DataTable dtReturn = new DataTable();
       PropertyInfo[] oProps = null;
       if (varlist == null) return dtReturn;
          foreach (T rec in varlist)
         {
          if (oProps == null)
         {
            oProps = ((Type)rec.GetType()).GetProperties();
             foreach (PropertyInfo pi in oProps)
             {
                  Type colType = pi.PropertyType;
                   if ((colType.IsGenericType) && (colType.GetGenericTypeDefinition() == typeof(Nullable<>)))
                 colType = colType.GetGenericArguments()[0];
                        dtReturn.Columns.Add(new DataColumn(pi.Name, colType));
             }
         }
       DataRow dr = dtReturn.NewRow();
         foreach (PropertyInfo pi in oProps)
           {
            dr[pi.Name] = pi.GetValue(rec, null) == null ? DBNull.Value : pi.GetValue
            (rec, null);
           }
         dtReturn.Rows.Add(dr);
}
return dtReturn;
}

12. Format the retrieve column using LINQ) 10. Delete a record using LINQ?9. Check the column value having specified characters using LINQ?8. Bind into gridview using LINQ?7. Bind into DropdownList using LINQ?6. Update Single value to particular record using LINQ 3. Encrpted Password2. insert Values into table using LINQ?

'Button1_Click' and no extension method 'Button1_Click' accepting a first argument of type 'ASP.feedback_aspx'

'ASP.feedback_aspx' does not contain a definition for 'Button1_Click' and no extension method 'Button1_Click' accepting a first argument of type 'ASP.feedback_aspx' could be found (are you missing a using directive or an assembly reference?)

Ans: After Delete the button and buttonl_Click event , it will thrown the above error while building because you didn't properly saved the file.

Save that file and rebuild the solution.

Wednesday, August 11, 2010

Partitioning Operators

Partitioning Operators are

1. Take
2. Skip
3. TakeWhile
4. SkipWhile

Example SQL Table is UserMsts

Fields : UserMstID, Name, EMail, CreateBy, CreateDate , Address

1. Take Simple Query

var Result = from objUserMst in UserMsts

select objUserMst;
foreach (var n in Result.Take(8))
Console.WriteLine (n.UserMstID + n.Name );

This Query uses Take to get only the first 8 records.

2. Skip

var Result = from objUserMst in UserMsts

select objUserMst;

foreach (var n in Result.Skip(3))

Console.WriteLine ("UserId="+n.UserMstID + "; Name = "+ n.Name );

This Query uses to SKIP first three record and retrieve rest of the records.

3. Retrieve records from 10 - 20 for the following results

Records

UserId=
UserId=admin
UserId=AZIZUL
UserId=D00281-000
UserId=D00304-000
UserId=D00611-000
UserId=D01619-000
UserId=D01745-000
UserId=D02669-000
UserId=D02670-0001
UserId=D02673-000
UserId=D02684-000
UserId=D02940-000
UserId=D03002-000
UserId=D03252-000
UserId=D06124-000
UserId=D09533-000
UserId=D09999-001
UserId=D10051-001
UserId=D10059-000
UserId=D11719-000
UserId=D12345-000
UserId=D99999-000
UserId=d99999-999
UserId=DAVID
UserId=Jason
UserId=mradmin
UserId=SOW
UserId=tech_it
UserId=TEST
UserId=test1
UserId=testing
UserId=Testing1

Query:
var Result = from objUserMst in UserMsts

select objUserMst;
foreach (var n in Result.Skip(10).Take(10))
Console.WriteLine ("UserId="+n.UserMstID );

Results:

UserId=D02673-000

UserId=D02684-000
UserId=D02940-000
UserId=D03002-000
UserId=D03252-000
UserId=D06124-000
UserId=D09533-000
UserId=D09999-001
UserId=D10051-001
UserId=D10059-000

4. TakeWhile

int[] numArray = { 1235, 4456, 1234, 3232, 1900, 80000, 6234, 7123, 2343,0 };

var FindNumbers = numArray.TakeWhile(n => n < 3232);
foreach (var objFindNumbers in FindNumbers)
{
Console.WriteLine(objFindNumbers);
}

The above query TakeWhile to return elements starting from the beginning of the array whether the given(3232) number is hit and retrieved less than 3232 numbers from the array

Output:

1235

Generate Password using C#

public string GeneratePassword()

{

Random rndNumber = null;

char[] chars = null;

try

{

int passwordLength = 8;

string allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ123456789";
chars = new char[passwordLength];

rndNumber = new Random();

for (int i = 0; i < passwordLength; i++)

{

chars[i] = allowedChars[rndNumber.Next(0, allowedChars.Length)];

}

}

catch

{

throw;

}

return new string(chars);

}