how to check if user is in database already ?

Tangara G

10y1.2k.NET

I have a form which requires new user to register. If they are already in the database, then they will be re-direct to the login page. If not, they can proceed with the user registration.

However, I am not sure what is wrong with my code cos even if the username is not found, it still direct them to the login page.

protected void Submit_Button_Click(object sender, EventArgs e)
{
using (Team6_PhoneOnlineShopEntities2 cntx = new Team6_PhoneOnlineShopEntities2())
{
//try
{
// var checkuser = from u in cntx.Users where u.userName == txtUserName.Text select u;
// var checkuser = from u in cntx.Users where txtUserName.Text == u.userName select u;
var checkuser = cntx.Users.FirstOrDefault(u => txtUserName.Text == u.userName);
//int a = Convert.ToInt32(txtUserId.Text);
// var User = cntx.Users.FirstOrDefault(m => m.userID == a);
// customer.userName = txtUserName.Text;
// String checkUser = "select Count(*) from User where userName = '" + customer.userName + "'";
if (checkuser == null)
{
User customer = new User();
customer.userName = txtUserName.Text;
customer.lastName = txtLastName.Text;
customer.userPassword = txtUserPassword.Text;
customer.userPassword = txtConfirmedPassword.Text;
customer.moblieNumber = txtMobileNo.Text;
customer.userAddress = txtAddress.Text;
customer.userEmail = txtEmail.Text;
customer.roleID = 1;
customer.paymentMethod = DropDownList1.SelectedValue;
cntx.Users.Add(customer);
cntx.SaveChanges();
lblMessageSuccess.Text = "successful registration";
}
else
{
lblMessageUser.Text = "You have registered before. Pls proceed to login";
Response.Redirect("/Login.aspx");
}
}
// Response.Redirect("SuperPhoneOnLineShop_Team6/ShoppingPage");// enter the right url here
}
}
}
}

I hope someone can point out what is the way to do my code so that it will turn out the way I want. Many thanks.

10 Replies

Know the answer? Post it — somebody with the same question will find it here.

Tangara G10y ago
Re Manas,
I am a beginner and that is where I am stuck ..
How do I validate if the user is already in the database before I use the LINQ ?
And without using javascript. How do you write that method ?
assuming I have a web service and DAO layer ?
If you can give me a quick illustration I will be most appreciative.
0
Imran Bashir10y ago
use this store procedure
CREATEprocsp_wuser_register
@user_namevarchar(50),
@passwordvarchar(50),
@first_namevarchar(50),
@last_namevarchar(50),
@addressvarchar(100),
@contactvarchar(50)
as
begin
declare@countint
declare@ReturnCodeint
Select@count=COUNT(user_name)fromuser_regwhereuser_name=@user_name
if@count>0
begin
set@ReturnCode=-1
end
else
begin
set@ReturnCode=1
insertintouser_regvalues(@user_name,@password,@first_name,@last_name,@address,@contact)
End
select@ReturnCodeasReturnValue
End

in project u call this like

protected void btnSubmit_Click(object sender, EventArgs e)
{
if (Page.IsValid)
{
using (db.con)
{
db.com = new SqlCommand("sp_user_register", db.con);
db.com.CommandType = CommandType.StoredProcedure;
//string khan = DateTime.Now.ToString();
db.com.Parameters.AddWithValue("@user_name",txtUserName.Text.Trim());
db.com.Parameters.AddWithValue("@password",txtPassword.Text.Trim());
db.com.Parameters.AddWithValue("@first_name ",txtFirstName.Text.Trim());
db.com.Parameters.AddWithValue("@last_name",txtLastName.Text.Trim());
db.com.Parameters.AddWithValue("@address",txtAddress.Text.Trim());
db.com.Parameters.AddWithValue("@contact",txtPhone.Text.Trim());
try
{
db.con.Open();
int ReturnCode = (int)db.com.ExecuteScalar();
if (ReturnCode == -1)
{
lblResult.Text = "user name is already in use";

}
else
{
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "alertMessage", "alert('Record Inserted Successfully')", true);
Response.AddHeader("REFRESH", "2;URL=regSalesman.aspx");
}
}
catch (Exception ex)
{
lblResult.Text = ex.Message;
}
}
}
else
lblResult.Text = "some Fields are missing";
}
}
0
Manas Mohapatra10y ago
You must have to validate the textbox value before you use LINQ.
0
Tangara G10y ago
Hi Manas,
Can I know why you are comparing with txtUserName.Text when the user has not even enter the text into the Textbox ?
int noOfUsers = cntx.Users.Count(u => u.userName == txtUserName.Text);
0
ali tuncer10y ago
Hi Karen,
Best way is to put a breakpoint and debug your code. If username does not exist, checkuser has to be null, so it shouldn't go to else part...you need to check the value of checkuser variable..
0
Tangara G10y ago
Hi Ali,
Form based there is a built in validator control to check plus regular express so the empty part is already taken care of.
Where as your linq statement it is the same as what I have been using.
var checkuser = cntx.Users.Where(u => u.userName == txtUserName.Text).FirstOrDefault();
Seems like here has nobody who knows the answer.....
Actually, I think I may have to write some validation method at in separate class and call it. If the result is negative..meaning the user is not exist, then I will let the user continue with the registration form....
0
Manas Mohapatra10y ago
Try with below code:
int noOfUsers = cntx.Users.Count(u => u.userName == txtUserName.Text);

if(noOfUsers == 0)
{
    // Add User to DB
}
0
ali tuncer10y ago
what if txtUserName.Text is empty? since you don't validate before you save, you might be saving empty values(blanks) to database..check the records in your database..
try this code to check is username exists :
var checkuser = cntx.Users.Where(u => u.userName == txtUserName.Text).FirstOrDefault();
0
Tangara G10y ago
Bikesh,
Your answer is incorrect cos it is not what I was asking for.
I need to check if the user is in the database and then if it is, I will need to direct the user to the login page, otherwise, the user will continue to fill up all the textbox form and able to submit the details to the database.
Assumption I already create the connectively layer ....so i just need that server validation portion....
0
Bikesh Srivastava10y ago
Hi karen.
use code like this to exist user.
protectedvoidbtn_check_Click(objectsender,EventArgse)
{
SqlConnectioncon=newSqlConnection(connStr);
con.Open();
str="selectcount(*)fromemployeewhereename='"+txtUserName.Text+"'";
com=newSqlCommand(str,con);
intcount=Convert.ToInt32(com.ExecuteScalar());
if(count>0)
{
lblMessage.Text="usernameexist";
}
else
{
lblMessage.Text="usernamedoesnotexist";
}
}
If its resolve your query mark as answer.
0