Visual Web Developer 2008
using VB

D:\ . . . \WebsiteX\AppCode\WebRecordVb

** code snippet begin **
Imports Microsoft.VisualBasic

Public Class WebDbRecord
  Private RestaurantId As Int32
  Private FromWebOrRestaurant As Byte
  Private SpeedOfService As Byte
  '. . etc . .

Public Function IsValid() As Boolean
  If  isnull(RestaurantId) Then

  End If
End Function
End Class

** code snippet end **

Why please is isnull creating a build error - name isnull is not declared ?
and what to do about it!

Jim Bunton

IsNull doesn't exists in VB.NET. Also in this context I'm not sure what you are trying to do (RestaurantId is an integer and will never be null, AFAIK it was previoulsy usefull only with the variant datatype in VB6).


Try http://msdn.microsoft.com/en-us/library/tckcces5(VS.80).aspx (IsDbNull function) or http://msdn.microsoft.com/en-us/library/ms235245.aspx (Nullable value types) or explain what you are trying to do...

As a side note Linq To SQL or Entity Framework or any other tool able to map database tables to .NET classes might be usefull for you...

  Visual Web Developer 2008
  using VB

  D:\ . . . \WebsiteX\AppCode\WebRecordVb

  ** code snippet begin **
  Imports Microsoft.VisualBasic

  Public Class WebDbRecord
    Private RestaurantId As Int32
    Private FromWebOrRestaurant As Byte
    Private SpeedOfService As Byte
    '. . etc . .

  Public Function IsValid() As Boolean
    If  isnull(RestaurantId) Then

    End If
  End Function
  End Class

  ** code snippet end **

  Why please is isnull creating a build error - name isnull is not declared ?
  and what to do about it!

  Jim Bunton

Thanks for your response to my posting Patrice:

Generally what I'm trying to do is I guess is
1. To map some responses on a web page into vb.net structures which I can then manipulate
    First dissapointment was that I couldn't create a structure datatype!
    had't found that vb.net is so unlike VB vin ordinaire!
    So - my first attempt to create a class - to hold the transformed/derived data values in
2. Validate data or whatever (I take your point about an integer never being null - I also found that IsEmpty wasn't available!
3. Design the 'Class' so it would have a method to write/edit/read to and from a database
4. Now hoping that I can figure out how to do the latter using Linq or Entity

As you can see - I'm struggling rather with concepts I've never used before with olde world asp & vb

Thanks again

Jijm
  IsNull doesn't exists in VB.NET. Also in this context I'm not sure what you are trying to do (RestaurantId is an integer and will never be null, AFAIK it was previoulsy usefull only with the variant datatype in VB6).


  Try http://msdn.microsoft.com/en-us/library/tckcces5(VS.80).aspx (IsDbNull function) or http://msdn.microsoft.com/en-us/library/ms235245.aspx (Nullable value types) or explain what you are trying to do...

  As a side note Linq To SQL or Entity Framework or any other tool able to map database tables to .NET classes might be usefull for you...

  --
  Patrice
    Visual Web Developer 2008
    using VB

    D:\ . . . \WebsiteX\AppCode\WebRecordVb

    ** code snippet begin **
    Imports Microsoft.VisualBasic

    Public Class WebDbRecord
      Private RestaurantId As Int32
      Private FromWebOrRestaurant As Byte
      Private SpeedOfService As Byte
      '. . etc . .

    Public Function IsValid() As Boolean
      If  isnull(RestaurantId) Then

      End If
    End Function
    End Class

    ** code snippet end **

    Why please is isnull creating a build error - name isnull is not declared ?
    and what to do about it!

    Jim Bunton

Both IsEmpty/IsNull were used with the variant datatype that is gone so those functions are gone...

The Type keyword is now Structure. I would suggest reading at least once the language specification you'll find at msdn.microsoft.com. It will discuss structures, classes and other language constructs...

  Thanks for your response to my posting Patrice:

  Generally what I'm trying to do is I guess is
  1. To map some responses on a web page into vb.net structures which I can then manipulate
      First dissapointment was that I couldn't create a structure datatype!
      had't found that vb.net is so unlike VB vin ordinaire!
      So - my first attempt to create a class - to hold the transformed/derived data values in
  2. Validate data or whatever (I take your point about an integer never being null - I also found that IsEmpty wasn't available!
  3. Design the 'Class' so it would have a method to write/edit/read to and from a database
  4. Now hoping that I can figure out how to do the latter using Linq or Entity

  As you can see - I'm struggling rather with concepts I've never used before with olde world asp & vb

  Thanks again

  Jijm
    IsNull doesn't exists in VB.NET. Also in this context I'm not sure what you are trying to do (RestaurantId is an integer and will never be null, AFAIK it was previoulsy usefull only with the variant datatype in VB6).


    Try http://msdn.microsoft.com/en-us/library/tckcces5(VS.80).aspx (IsDbNull function) or http://msdn.microsoft.com/en-us/library/ms235245.aspx (Nullable value types) or explain what you are trying to do...

    As a side note Linq To SQL or Entity Framework or any other tool able to map database tables to .NET classes might be usefull for you...

    --
    Patrice
      Visual Web Developer 2008
      using VB

      D:\ . . . \WebsiteX\AppCode\WebRecordVb

      ** code snippet begin **
      Imports Microsoft.VisualBasic

      Public Class WebDbRecord
        Private RestaurantId As Int32
        Private FromWebOrRestaurant As Byte
        Private SpeedOfService As Byte
        '. . etc . .

      Public Function IsValid() As Boolean
        If  isnull(RestaurantId) Then

        End If
      End Function
      End Class

      ** code snippet end **

      Why please is isnull creating a build error - name isnull is not declared ?
      and what to do about it!

      Jim Bunton

Thanks again Patrice.

I guess reading the language spec, 374 pages! is going to keep me busy for a while.

Your pointers as to where to go are much appreciated.

Jim
  Both IsEmpty/IsNull were used with the variant datatype that is gone so those functions are gone...

  The Type keyword is now Structure. I would suggest reading at least once the language specification you'll find at msdn.microsoft.com. It will discuss structures, classes and other language constructs...

  --
  Patrice


    Thanks for your response to my posting Patrice:

    Generally what I'm trying to do is I guess is
    1. To map some responses on a web page into vb.net structures which I can then manipulate
        First dissapointment was that I couldn't create a structure datatype!
        had't found that vb.net is so unlike VB vin ordinaire!
        So - my first attempt to create a class - to hold the transformed/derived data values in
    2. Validate data or whatever (I take your point about an integer never being null - I also found that IsEmpty wasn't available!
    3. Design the 'Class' so it would have a method to write/edit/read to and from a database
    4. Now hoping that I can figure out how to do the latter using Linq or Entity

    As you can see - I'm struggling rather with concepts I've never used before with olde world asp & vb

    Thanks again

    Jijm
      IsNull doesn't exists in VB.NET. Also in this context I'm not sure what you are trying to do (RestaurantId is an integer and will never be null, AFAIK it was previoulsy usefull only with the variant datatype in VB6).


      Try http://msdn.microsoft.com/en-us/library/tckcces5(VS.80).aspx (IsDbNull function) or http://msdn.microsoft.com/en-us/library/ms235245.aspx (Nullable value types) or explain what you are trying to do...

      As a side note Linq To SQL or Entity Framework or any other tool able to map database tables to .NET classes might be usefull for you...

      --
      Patrice
        Visual Web Developer 2008
        using VB

        D:\ . . . \WebsiteX\AppCode\WebRecordVb

        ** code snippet begin **
        Imports Microsoft.VisualBasic

        Public Class WebDbRecord
          Private RestaurantId As Int32
          Private FromWebOrRestaurant As Byte
          Private SpeedOfService As Byte
          '. . etc . .

        Public Function IsValid() As Boolean
          If  isnull(RestaurantId) Then

          End If
        End Function
        End Class

        ** code snippet end **

        Why please is isnull creating a build error - name isnull is not declared ?
        and what to do about it!

        Jim Bunton

AS a VB6 developer try perhaps :
http://msdn.microsoft.com/en-us/library/ms172618.aspx (from a whole section for BV6 developer in the VS 2008 help).

For the spec, I would say chapter 7 so that you know about handling data. Then perhaps chapter 4 for OOP programming concepts... Then see the chapter titles so that you can pick possible references you would need and try to have a closer look at least once not to be proficient but at least to know what exists so that you can dig deeper as needed...

I allow you not to read the grammar summary

  Thanks again Patrice.

  I guess reading the language spec, 374 pages! is going to keep me busy for a while.

  Your pointers as to where to go are much appreciated.

  Jim
    Both IsEmpty/IsNull were used with the variant datatype that is gone so those functions are gone...

    The Type keyword is now Structure. I would suggest reading at least once the language specification you'll find at msdn.microsoft.com. It will discuss structures, classes and other language constructs...

    --
    Patrice


      Thanks for your response to my posting Patrice:

      Generally what I'm trying to do is I guess is
      1. To map some responses on a web page into vb.net structures which I can then manipulate
          First dissapointment was that I couldn't create a structure datatype!
          had't found that vb.net is so unlike VB vin ordinaire!
          So - my first attempt to create a class - to hold the transformed/derived data values in
      2. Validate data or whatever (I take your point about an integer never being null - I also found that IsEmpty wasn't available!
      3. Design the 'Class' so it would have a method to write/edit/read to and from a database
      4. Now hoping that I can figure out how to do the latter using Linq or Entity

      As you can see - I'm struggling rather with concepts I've never used before with olde world asp & vb

      Thanks again

      Jijm
        IsNull doesn't exists in VB.NET. Also in this context I'm not sure what you are trying to do (RestaurantId is an integer and will never be null, AFAIK it was previoulsy usefull only with the variant datatype in VB6).


        Try http://msdn.microsoft.com/en-us/library/tckcces5(VS.80).aspx (IsDbNull function) or http://msdn.microsoft.com/en-us/library/ms235245.aspx (Nullable value types) or explain what you are trying to do...

        As a side note Linq To SQL or Entity Framework or any other tool able to map database tables to .NET classes might be usefull for you...

        --
        Patrice
          Visual Web Developer 2008
          using VB

          D:\ . . . \WebsiteX\AppCode\WebRecordVb

          ** code snippet begin **
          Imports Microsoft.VisualBasic

          Public Class WebDbRecord
            Private RestaurantId As Int32
            Private FromWebOrRestaurant As Byte
            Private SpeedOfService As Byte
            '. . etc . .

          Public Function IsValid() As Boolean
            If  isnull(RestaurantId) Then

            End If
          End Function
          End Class

          ** code snippet end **

          Why please is isnull creating a build error - name isnull is not declared ?
          and what to do about it!

          Jim Bunton

Show quote Hide quote IsNull() is not native in VB.NET. Perhaps in the compatibility namespace
but not straight up.

Also, an int cannot have a null value. It is set to 0 when declared. you
can use a nullable int, but the test is:

If Not (RestaurantId.HasValue) Then

if you are using nullable int.


Show quoteHide quote

Thanks for your response to my posting Gregory.
I take your point about isnull(integervar) being inappropriate
I also found isEmpty() wasn't available

If Not (RestaurantId.HasValue) Then

Looks like there's a whole world there that I don't know about
Can't seem to find a list of  HasValue and similar 'Natives' to Vb.Net in the help files
[In fact notNull and isEmpty are (confusingly) covered with examples in Help!]

OR intellisense so, if I type
If Not(RestaurantId.
HaveValue doesn't appear in the(all)  list of possibilities


What I'm trying to do is Transform responses on a web page into a vb.net structure (trying to use a 'class' to do this)
Then have  methods in the class which will write/read/edit the database
My first attempt at using classes! as you migh have guessed.

Patrice above has suggested using Linq or Entity Framework tools. I'll have a looksee.

Thanks again

Jim

Show quoteHide quote

Jim Bunton wrote:
ICBW, but, tools->options->text editor->Basic->Auto list members/Hide
advanced members check box.

Andrew

Show quote Hide quote This is only valid with nullable types, which are declared, in VB, like
so:


Dim RestaurantId as Nullable(Of Integer)

You can then use the HasValue test on it.If you use a standard Integer,
it will fetter out like this:


Dim RestaurantId as Integer

Console.WriteLine(RestaurantId)

This will print 0, not Nothing or Null, as Integers are automatically
initialiazed. Strings will stay null however.


Only with nullable types.

Something like this:

Dim RestaurantIdString as String = Request("RestaurantId")

If Not(RestaurantId Is Nothing) Then
        'Run code for restaurant
Else
        'Run code indicating there is no restaurant with this id
End If

You can then turn the Restaurant Id into an integer, like so:

If Not (RestaurantId Is Nothing) Then
        Dim RestaurantId as Integer

        If(Int32.TryParse(RestaurantIdString, RestaurantId) Then
                'Process ID
        End If
End If


I think LINQ can solve a lot of problems, but if getting the Id off the
query string is the biggest issue, you still have to solve that.
Hopefully, I have given you some good pointers.


Show quoteHide quote

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