[RESOLVED] Calling a Sub in a Different aspx.vb File

[jwesleycooper]

I need to call a sub which must be contained within a separate web page, but even though it is declared as public, when I call it like this:

Cart.addMovie(ByVal title As String, ByVal format As String, _
                      ByVal copies As Integer, ByVal price As Double)

I'm getting this error:

Error	1	Reference to a non-shared member requires an object reference.	C:\Documents and Settings\John Wesley Cooper\My Documents\College\cis259\MovieStore\MovieStore\Default.aspx.vb	48	9	MovieStore

...so what must I do to call this procedure as I need to?

[motil]

i don't think your web app should even compile when you try to call like this...

you want to call it not declare it

Cart.addMovie(title,format, _
                      copies, price)

make sure that : title, format, copies, price has values...

[gep13]

Hey,

Where is Cart instantiated?

I would question why you need to use this approach. If the method that is on the other page is common to both, then I would recommend that you extract that method and put in it's own class, and put it in the App_Code folder, or perhaps even it's own class library.

Gary

[mendhak]

Calling a method in another page requires you to instantiate that other page, which is a waste of resources. When you move addMovie to a common class, you can make it static/shared if you like.

Declare a class called CartHelper and put your method in there. If your addMovie method talks to any UI elements then you'll need to separate that logic out as well, make it a standalone function that does something and returns something without touching any controls.

[jwesleycooper]

What I need to do is use values that are selected/specified on the 1st page as input for variables on the second... so what would be the best course of action in this case, and how exactly can I do such?

[mendhak]

Pass it to the second page. A common way to do this is the querystring. On Page1, when the first 'value' is selected,

Response.Redirect("Page2.aspx?category=Books")

On Page2, you read the category using Request.QueryString("category")

[jwesleycooper]

The values need to all be sent at the same time, so would this work from within my cartButton_Click Sub? Additionally, one of the values I need must be taken from my database via the Cart (2nd) Form and placed into a contructor as a parameter there... So what must I do to accomplish all of this?

[brin351]

You can pass many values in a querystring like Page2.aspx?category=Books&var2=aaa&var3=bbb etc

You retreve them by name on the 2nd page Request.QueryString("category") Request.QueryString("var2") etc..

When you get the value from the database is up to you. You could do it on the 2nd page before calling the cart method....

[jwesleycooper]

I just implemented it as you all indicated, but the passed values are not loading as I need them to, though they are placed into the request url... So here's my code so far:

1st page:

Private Sub cartButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cartButton.Click
        Response.Redirect("Cart.aspx?title=" & titleDropDownList.SelectedItem.Text _
                          & "&format=" & formatDropDownList.SelectedItem.Text _
                          & "&copies=" & quantityTextBox.Text)
    End Sub

and the 2nd:

Public Partial Class Cart
    Inherits System.Web.UI.Page
    Private inCart As ArrayList = New ArrayList()

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Request.ToString.Contains("?") Then
            Dim selectedItem As CartItem = New CartItem(Request.QueryString("title"), _
                                                        Request.QueryString("format"), _
                                                        Integer.Parse(Request.QueryString _
                                                                     ("copies")))
            If inCart.Count > 1 Then
                Dim x As Integer = 0
                Dim identical As Boolean = False
                Do
                    If inCart.Item(x).IsIdentical(selectedItem) Then
                        identical = True
                        x = inCart.Count
                    Else
                        x = x + 1
                    End If
                Loop Until x = inCart.Count
                If Not identical Then
                    inCart.Add(selectedItem)
                End If
            Else
                inCart.Add(selectedItem)
            End If
        End If
        For Each i As CartItem In inCart
            cartCheckBoxList.Items.Add(i.Copies & " copies of " & i.Title & " in " _
                                       & i.Format & " format at $" & i.PricePerCopy _
                                       & " each")
        Next
    End Sub

    Private Sub calcTotal()
        Dim numberMovies As Integer = 0
        Dim totalPrice As Double = 0.0
        If inCart.Count > 1 Then
            For c As Integer = 0 To inCart.Count - 1
                numberMovies = numberMovies + inCart.Item(c).Copies()
                totalPrice = totalPrice + inCart.Item(c).Copies() _
                    * inCart.Item(c).PricePerCopy()
            Next
        Else
            numberMovies = inCart.Item(0).Copies()
            totalPrice = numberMovies * inCart.Item(0).PricePerCopy()
        End If
        totalLabel.Text = "Total Movies: " & numberMovies & ControlChars.Tab _
            & "Total Price: $" & totalPrice
    End Sub

    Public Class CartItem
        Private _title As String
        Private _format As String
        Private _copies As Integer
        Private _pricePerCopy As Double

        Public Sub New(ByVal title As String, ByVal format As String, _
                       ByVal copies As Integer)
            _title = title
            _format = format
            _copies = copies
            If format.Equals("VHS") Then
                _pricePerCopy = 9.99
            Else
                _pricePerCopy = 19.99
            End If
        End Sub

        Public ReadOnly Property Title() As String
            Get
                Return _title
            End Get
        End Property

        Public ReadOnly Property Format() As String
            Get
                Return _format
            End Get
        End Property

        Public ReadOnly Property Copies() As Integer
            Get
                Return _copies
            End Get
        End Property

        Public ReadOnly Property PricePerCopy() As Double
            Get
                Return _pricePerCopy
            End Get
        End Property

        Public Function IsIdentical(ByVal movie As CartItem) As Boolean
            If Title = movie.Title AndAlso Format = movie.Format Then
                Return True
            Else
                Return False
            End If
        End Function
    End Class
End Class

So what's wrong here?

[gep13]

Hey,

Have you tried stepping into the code? Have you set any breakpoints?

Out of interest, why did you choose to do this:

If Request.ToString.Contains("?") Then

Did you see that somewhere?

Gary

[jwesleycooper]

...Out of interest, why did you choose to do this:

If Request.ToString.Contains("?") Then

Did you see that somewhere?

Gary

That's where the problem was! It seems that the .ToString method didn't return the actual contents of the Request, thus not adding anything to the cart! I was adding that line in case this page were somehow called without any queriable input, so to prevent any exceptions from being raised via null input... or could that even cause a problem in these circumstances? If so, how can I set this up to not add a null CartItem to my ArrayList whenever the Cart page is called without passed values?

Oh yes, and how can I prevent the previous CartItem(s) from being removed when the user navigates away from the cart page?

[gep13]

Ah, hold on, looking at that again, that would never work. You would need to use another member of the Request Class, i.e. the Url Property if you wanted to use that approach:

http://msdn.microsoft.com/en-us/libr...t_members.aspx

The correct approach to this though would be to check for the QueryString parameters that you need to continue, if there isn't one that you need to continue, throw a new ArgumentException.

Gary

[jwesleycooper]

...but how do I keep my inCart ArrayList variable from being cleared when the user leaves the page?

[selanec]

you can either store its value(s) into database or Session object. In that way your arraylist will keep having the previous items. I suggest database (table shoppingcart) and using cookie to identify the shopcart ID.

[gep13]

selanec is pretty much spot on.

The only other thing that I would mention is the use of the ArrayList. I think you would be better off altering the code to use a generic list, rather than limiting yourself to this.

Gary

[jwesleycooper]

I was considering that at first, but I don't know how to add records to a data table via vb code, no one in the Database Development forum will tell me how on earth to do this, and the textbook I've got doesn't even mention it! So could somebody please tell me how this is done?!?

[gep13]

Hey,

I am not clear on exactly what you are referring to. Can you elaborate? Or perhaps show the code that you are now using?

Gary

[jwesleycooper]

What I need to be able to do is add the data selected/inputted by the user on the first page into a new record in a pre-constructed cart table of my database... but I haven't a clue how to do this.

[gep13]

Hey,

So what you need to learn about is ADO.Net. There are a number of links in my signature that will help you learn up on this, but the basic steps are as follows:

1) Create a connection to your database
2) Create a command object with the necessary query that you need to insert/update/read/delete the information in the database
3) Create any parameters that are needed and add them to the command
4) Execute the command
5) Iterate the results if required.

Gary

[mendhak]

Read an ADO.NET tutorial. You want to pay specific attention to calling a stored proc from code (which can do the insert for you)

[jwesleycooper]

Three dumb questions I need answered ASAP:

1. How can I set-up my CartTable to automatically generate an ID field whenever the rest of a record inserted?
2. How do I implement structured exception handling for Edit and Insert commands automatically generated for a DetailsView Component?
3. How can I utilize ReportViewer controls to create a separate page that displays the entire store inventory?

[selanec]

I will answer just the 1st question.

Usually you generate cartid by yourself. Then when you deal with the table you check the cookie and if it not exists you generate new cartID:

Dim cartId As String = Guid.NewGuid.ToString

The field datatype that you store this value in, is char(36)

[gep13]

Hey,

1) Either the above, or you can configure the database to do this for you. Either with a GUID, as described, or have it as an AutoIncrementing field.

2) Don't. I would strongly urge you to take more control over the commands that are being generated for you. That way you have more flexibility, and know exactly what is going on in your code.

3) http://msdn.microsoft.com/en-us/libr...7(SQL.80).aspx

Gary

[jwesleycooper]

How do I make the field autoincrement?

Additionally, though I understand that I'd be better off defining the commands myself, I really need to get this project done right away; so I need to know how I can modify just the exception handling this time around.

[gep13]

Hey,

What database are you using? SQL Server? MySQL?

Each database is different.

You can do it through a SQL Query as defined here:

http://www.w3schools.com/Sql/sql_autoincrement.asp

But it's easier to do this in a database IDE, such as SQL Server Management Studio.

That's just it though, doing it using wizards, datasources, etc, means that you are limited in what you can actually do. For instance, the only thing you might be able to do is this:

http://www.15seconds.com/issue/030102.htm

However, if you implement it in code, you have far more control over the exception handling.

Gary

[jwesleycooper]

What I need to do is not only prevent the user from entering a null value, or one that cannot be contained by the datatype used, but also prevent passable yet incorrect values from being placed into my SQL Server Database. For instance, the format feild should only contain either a "VHS" or a "DVD" value... but a user could still enter "VH", or "vhs", which would cause problems for processing later on. How can I define and throw an exception for this kind of issue?

[selanec]

I would do this on the client-side using the built-in Validator controls. Of course you can always make an extra checking on the server-side but usually you do it on the client-side.
you just specify which TextBox control to be validated and add some regular expression for the pattern you want it matches and voila. That's pretty simple model to be implemented.

[jwesleycooper]

So how do I incorporate Validator controls into my DetailsView?

[gep13]

Hey,

It is not just on the client side that you need to do this, you need to do this on the server side as well. However, the ASP.Net Validation controls do both for you

You would need to create a TemplateField for each of the values that you want to validate, then add the necessary validation control:

http://www.asp.net/(S(pdfrohu0ajmwt4...ial-19-vb.aspx

Hope that helps!

Gary

[jwesleycooper]

How can I make my validator check that the input for and SKU contains 6 numeric characters, that the Format is either "VHS" or "DVD", that the rating is one of several possible values, and that the runtime is entered as 2 numbers, a colon, and two more numbers? The compare validator only seems to check against a single static value, and I have no idea how to implement a custom validator...

[jwesleycooper]

Figured it out from studying the MSDN Page on CustomValidators!

Actually, I think I've resolved all of my issues now! Thanks a million gep13, you're a life-saver!

[gep13]

Hey,

Ah, yeah, I should have mentioned that the CustomValidator might be the way to go. Did you implement both the client and server side check?

Gary

[mendhak]

Three dumb questions I need answered ASAP:

1. How can I set-up my CartTable to automatically generate an ID field whenever the rest of a record inserted?
2. How do I implement structured exception handling for Edit and Insert commands automatically generated for a DetailsView Component?
3. How can I utilize ReportViewer controls to create a separate page that displays the entire store inventory?

1 - If it's a database table make it autoincrement. If it's a datatable (in code), use a new Guid if you need a unique ID. What you do depends on how you'll be using it.

2 - Try Catch around it?

[mendhak]

What I need to do is not only prevent the user from entering a null value, or one that cannot be contained by the datatype used, but also prevent passable yet incorrect values from being placed into my SQL Server Database. For instance, the format feild should only contain either a "VHS" or a "DVD" value... but a user could still enter "VH", or "vhs", which would cause problems for processing later on. How can I define and throw an exception for this kind of issue?

Then don't give them the choice. Use a dropdownlist so that they can pick from a list of predetermined values, that's the purpose of DDLs - to get the user to pick from a specific list rather than typing it in freely. If you use a textbox and custom validation, there'll always be a way around it unless you validate client side as well, but then it still sucks because

1) It's not intuitive to the user
2) Duplicating effort

[mendhak]

How can I make my validator check that the input for and SKU contains 6 numeric characters, that the Format is either "VHS" or "DVD", that the rating is one of several possible values, and that the runtime is entered as 2 numbers, a colon, and two more numbers? The compare validator only seems to check against a single static value, and I have no idea how to implement a custom validator...

And this would be a Regular Expression Validator.

[gep13]

Ah, good point, never occurred to me to suggest a DDL. Thinking about it, this would make much more sense.

Gary