ASP.net with Entity Framework

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Hello,
I am having a problem i.e.,
I have a subject column in database...now i can add subject to the gridview using entity framework
but unable to check whether the subjects are already present in my database...please can anyone help me by suggesting the code.

C#

onlinequizEntities ob = new onlinequizEntities();
protected void Page_Load(object sender, EventArgs e)
{
   show();
}

protected void btn_subjsub_Click(object sender, EventArgs e)
{
   //having problem here...i want to check here whether subjects r already present in the
   //gridview, if present it will stop adding
   Sub ob1 = new Sub();
   ob1.Subject = txt_adminsub.Text;
   ob.Sub.AddObject(ob1);
   ob.SaveChanges();
   show();
}

protected void btn_subres_Click(object sender, EventArgs e)
{
   Response.Redirect("Subject.aspx");
}

public void show()
{
   var res = from abc in ob.Sub select abc;
   gv.DataSource = res;
   gv.DataBind();
}

public void gv_RowCommand(object sender, GridViewCommandEventArgs e)
{
   if (e.CommandName == "Delete")
   {
      int id1 = Convert.ToInt32(e.CommandArgument);
      var res = (from test1 in ob.Sub where test1.Sub_id==id1 select test1).ToList();
      foreach (var row in res)
      {
         ob.Sub.DeleteObject(row);
      }
      ob.SaveChanges();
      Response.Redirect("");
   }
   else if (e.CommandName == "Edit")
   {
      int id1 = Convert.ToInt32(e.CommandArgument);
      var sub = (from test in ob.Sub where test.Sub_id==id1 select test).ToList();
      foreach(var r in sub)
      {
         if (r.Subject == txt_adminsub.Text)
         {
            Response.Redirect("");
         }
         else
         {
            r.Subject = txt_adminsub.Text;
         }
      }
      ob.SaveChanges();
      Response.Redirect("");
   }
}

Posted 26-Dec-13 3:17am

Member 10488678

Updated 26-Dec-13 6:04am

Nelek

v3

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Comments

Sampath Lokuge 26-Dec-13 9:38am

Can you put the code snippet which you have written so far for the EF Query?

Member 10488678 26-Dec-13 10:34am

onlinequizEntities ob = new onlinequizEntities();
protected void Page_Load(object sender, EventArgs e)
{

show();

}
protected void btn_subjsub_Click(object sender, EventArgs e)
{
//having problem here...i want to check here whether subjects r already present in the //gridview, if present it will stop adding
Sub ob1 = new Sub();
ob1.Subject = txt_adminsub.Text;
ob.Sub.AddObject(ob1);
ob.SaveChanges();
show();

}

protected void btn_subres_Click(object sender, EventArgs e)
{
Response.Redirect("Subject.aspx");
}
public void show()
{
var res = from abc in ob.Sub select abc;
gv.DataSource = res;
gv.DataBind();
}

public void gv_RowCommand(object sender, GridViewCommandEventArgs e)
{
if (e.CommandName == "Delete")

{
int id1 = Convert.ToInt32(e.CommandArgument);
var res = (from test1 in ob.Sub where test1.Sub_id==id1 select test1).ToList();
foreach (var row in res)
{
ob.Sub.DeleteObject(row);
}
ob.SaveChanges();
Response.Redirect("");

}

else if (e.CommandName == "Edit")

{
int id1 = Convert.ToInt32(e.CommandArgument);
var sub = (from test in ob.Sub where test.Sub_id==id1 select test).ToList();
foreach(var r in sub)
{
if (r.Subject == txt_adminsub.Text)
{
Response.Redirect("");
}
else
{
r.Subject = txt_adminsub.Text;
}

}
ob.SaveChanges();
Response.Redirect("");
}

ZurdoDev 26-Dec-13 9:50am

Where are you stuck?

Member 10488678 26-Dec-13 10:37am

i have uploaded the code in above comment..please go through

ZurdoDev 26-Dec-13 10:44am

Can you specify where you are stuck instead of just showing a bunch of code?

Member 10488678 26-Dec-13 11:01am

protected void btn_subjsub_Click(object sender, EventArgs e)
{
//having problem here...i want to check here whether subjects r already present in the //gridview, if present it will stop adding
Sub ob1 = new Sub();
ob1.Subject = txt_adminsub.Text;
ob.Sub.AddObject(ob1);
ob.SaveChanges();
show();

}

Sampath Lokuge 26-Dec-13 11:07am

Is subject column primary key on your tbl ?

Member 10488678 26-Dec-13 11:12am

no sub_id is the primary key

Sampath Lokuge 26-Dec-13 11:20am

it seems you can have same subject name for more than once per 2 different sub_ids ? so then you have to send the sub_id for test to check the existence in db.

Member 10488678 26-Dec-13 11:29am

ya thanx got u

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JoCodes · Accepted Answer · 2013-12-26T05:15:00

Try something like

C#

using (onlinequizEntities  ob= new onlinequizEntities ())
        {
Sub ob1 = new Sub();
ob1.Subject = txt_adminsub.Text;
 if(!ob.Sub.Any(subject => subject.Subject == ob1.Subject))
        {
                ob.Sub.AddObject(ob1);
                ob.SaveChanges();
        }
}

Try and revert
PS : The best way is to set which ever Unique column as Unique Constraint in Table since the above
cannot ensure uniqueness in case of concurrent insertion or updations from different users.
Hope this helps...