Logins

Logins

• pfd

  OK hope you didnt see the earlier post , but

  I feel like a dummy now.

  How do you handle 3 connection strings

  Davids Learning

  
  

• Gerhardo

  what is a good example, and where does she go

  I got the login to function like it should, thanks again!

  Is there a way to keep the form from melting away, looks kinda sick just fading out when the login completes.

   

  Ah yea by the way do I have to call that in every form, or once your logged in does it take care of itself

  Davids Learning

  
  

• MuscleHead

  Richard_Wolf wrote:

  If your user is loggin' in that often, Reed, there may be other issues at play

  Agreed.

  In the login scenario we wouldn't expect there to be any large number of exceptions and the extra few milliseconds shouldn't be noticed. I just figured that as long as we were throwing some asides out there, we should cover all the bases.

  
  
  

• Chad Campbell

  One comment on Reed's suggestion of checking the ex.Message for a text string....

  You can check for multiple exception objects within the Try block.  For example:

       Try
           Conn.Open
           'work with connection, etc.
       Catch SqlErr as System.Data.SqlClient.SqlException
           'in here you know an error specific to the SQL client occured
       Catch ex as System.Exception
           msgbox "Unexpected error: " & ex.message
      End Try

  The more information you can give your users, the eaiser your job will be ;)

  
  

• progames25

  OK, you can't hard code "LoginForm2.LoginName" inside of the connection string.

  The connection string should initially end with ".mdf". There should be no username or password in the connection string that is stored in My.Settings.

  After the call to:

  My.Forms.LoginForm2.ShowDialog()

  add the lines:

  Dim NewConStr As String
  NewConStr = String.Format("{0};UID={1};PWD={2}", My.Settings.ConnectionString, LoginForm2.LoginName, LoginForm2.Password)
  Me.COFTableAdapter.Connection.ConnectionString = NewConStr

  then you can make the call to:

  Me.COFTableAdapter.Fill(Me.DataSet1.COF)

  In the code above, "My.Settings.ConnectionString" will be replaced with the name of the stored connection string setting. The String.Format() method is going to replace each of the {} items with the values supplied after the string.

  
  
  

• qrli

  Well, to specify the user account using SQL Authentication, you just set the username and password on the connection in code before calling any methods that would open the connection. That account has to exist in SQL. If the username and password are the same it both SQL and the application then you can pass the same login info from the app to the database.

  You kind of lost me with the "use the login for my app instead of embedding one in my application"... I'm not sure if this means that you already have a login form for you application and don't want to create a seperate form for SQL, but that's how I'm taking it.

  You can certianly do this - you'll just have to keep the accounts synchronized. You might watch for a database login failure error and respond by give the user an opportunity to change the password in the database.

  
  
  

• schveiguy

  As usual, you have several options.

  You could implement a property on the LoginForm to get the values; but this probably isn't necessary as the controls on the form are already accessible (unless you've changed the modifer from Friend). So you could just say: loggeduser = LoginForm.TextBox1.Text

  More likely though, you'll want to cache this info in your app (it can be argued that you shouldn't cache passwords but in this case it should be fine). So you might add two strings to your My.Settings collection called CurrentUser and CurrentPassword. Then after authenticating the user on the login form, you store the credentials in those string settings. Now you can access them whenever you want - to log into the database, or just to have a label display "Welcome Username!".

  
  
  

• Lawrence Parker

  Richard is correct; his example will give you an exception object with more SQL specific detail.

  However, you'll still need to check the SqlException object to determine the type of error (e.g. perhaps the database isn't available). With the SqlException there is a Number property that you could test for 18456, which would be the login failed error number.

  Keep in mind that generating exceptions is expensive, and casting the exception into a derived type increases the expense. In this case, catching the System.Exception will be several milliseconds faster than catching the SqlClient.SqlException.

  
  
  

• Amnesyc

  If your user is loggin' in that often, Reed, there may be other issues at play
  

• ShadowOfTheBeast

  Does your application already have a login mechanisim If not, then do as you say and add one that occurs during the app startup. Handle authenticating the user into your app. Then add the current username and password to the connection string. The connection string should be store in My.Settings. While it's not written in Basic, it is easy to parse. Just modify the value by removing the "User Id= xxxxx;" part. Then, in code, you set the TableAdapter.Connection.ConnectionString = My.Settings.ConnectionString & ";User Id = loggeduser; Password = suppliedpassword" where "loggeduser" and "suppliedpassword" are the username and password from the application login. Now you can call the Fill() method on the TableAdapter, using the current user's credentials.

  Now, whenever you allow the user to change their password in the application, you must also use the System.Data.SqlClient.SqlConnection.ChangePassword() method to update the database password.

  You can catch a login error by performing your TableAdapter.Fill() method within a Try-Catch block. You can test the exception message to see if it is a login error: If ex.Message.StartsWith("Login failed for user") Then.

  HTH

  
  
  

• ron nash

  Remember, everything is a class.  Add a couple of properties to your login form:

  Public Property LoginName() As String
       Get
            LoginName = Textbox1.Text
       End Get
       Set (byval value as string)
            Textbox1.Text = Value
       End Set
  End Property

  Then you can reference the properties from your other form:

      ConnString = ConnString & "User ID = " & LoginForm.LoginName & ";"
      ConnString = ConnString & "Password = " & LoginForm.Password & ";"

  
           
  

  
  

• RobLearningVisualBasic

  User Id = loggeduser; Password = suppliedpassword"

  how do you pass that from the login form

  Davids Learning

  
  

• nub340

  just set the username and password on the connection in code

  do you mean pass the user info from the dialog to your connection string

  if so how would you add it, i have looked at the connection string code and it dont look like vb to me

  so basically what i think your saying is have a dialog that is modal when your main form opens, pass the info from there to SQL.

  How do you catch the fail if what they enter is not right

  Thanks for helping

  Davids Learning

  
  

• OOMama

  Having a little problem

  I made the classes like you said

  made a msgbox to show me the results - there fine - thank you for teaching me that by the way.

  but when I go to my connection string I run into a problem

  what you gave didnt work - it said that & was an illegal operand i think

  and it fused about User ID

  anyhow I tried this

  this is the end of my conn string .mdf;UID=LoginForm2.LoginName;Pwd=LoginForm2.Password "

  It failed, it said login failed for "LoginForm2.LoginName"

  I did make my loginform2.showdialog

  I put this in the mainform's on load event - the last line was already there

  My.Forms.LoginForm2.ShowDialog()

  Me.COFTableAdapter.Fill(Me.DataSet1.COF)

  Can you help with this

  Davids Learning

  
  
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