Using VB2008 to acccess the Betfair API: A tutorial

[willyray1]

Hi Mumbles, thanks for this thread. I`m attempting to write a bet bot. I am storing my marketIds, selectionIds into a dim array. but I am having trouble retriving the event date/time. Can you suggest which API call to make, and when to call it?

Thanks again John Moore

Hi John

Depends on when/how you call your market but you could use the PopulateTreeView routine and bung it in the tag of the node:
Node.Name = Ids(j) 'This is the key
Node.Tag = Format(.eventDate, "HH:mm")
Nodes.Add(Node)

When you call your market just use the tvMarkets.SelectedNode.Tag and bung it in a variable or use it straight away.

[Mumbles0]

Reply to John Moore (re: Event times)

I not exactly sure of your problem, but you should have the date & time info already without having to make an additional call. If you have called getAllMarkets to get your marketId, then the .eventDate parameter countains the scheduled market start time for each returned market. You have probably called getMarket to get your selectionIds. This call returns a parameter called .marketTime which contains the same info. These parameters are of type DateTime which have both date and time parts.

[Mumbles0]

Reply to daylosh (re: Step 6 code)

The code shown in step 6 already includes 'string.split'. This executes as fast as I can get it. No more changes are required (unless, of course, you can think of any improvements).

[Mumbles0]

Reply to Vadim (re: updateBets)

All parameters in the request object should be assigned:

With oUpdateBets
  .betId = 7919011854
  .newBetPersistenceType = BFUK.BetPersistenceTypeEnum.NONE
  .newPrice = 1000
  .newSize = 4.5
  .oldBetPersistenceType = BFUK.BetPersistenceTypeEnum.NONE
  .oldPrice = 1000
  .oldSize = 4
End With

The API Guide says include the old values, so do this.
General rule is don't omit parameters unless you're sure it's OK to do so.

Also, change this line further down in your code:

If .errorCode = BFUK.UpdateBetsErrorEnum.OK Then

This did not cause the problem, but is more correct.

[Vadim]

Multithreading and UI problem

Mumbles0, method that you described in step 11 is good, but if you interact with the user interface is used BeginInvoke.
I try to modify the code using BeginInvoke:

Imports System.Threading
Public Class ThreadForm
    Public Delegate Sub dPrint(ByVal tLog As TextBox, ByVal Message As String) 'Delegate
    Private StopFlag As Boolean
    Public Sub Print(ByVal tLog As TextBox, ByVal Message As String)
        With tLog
            .SelectionStart = .Text.Length
            .SelectedText = vbCrLf & Message
        End With
    End Sub

    Sub DoTheWork()
        Do
            Print("My message")   '??????????????
        Loop Until StopFlag
        Beep()
    End Sub

   Private Sub bStart_Click(ByVal sender As Object, ByVal e As EventArgs) Handles bStart.Click
        StopFlag = False
        bStart.Enabled = False
        Dim Fred As New Thread(AddressOf DoTheWork)
        tLog.BeginInvoke(New dPrint(AddressOf Print), Fred) 'BeginInvoke
        Fred.Start()
    End Sub

    Private Sub bStop_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bStop.Click
        StopFlag = True
        bStart.Enabled = True
    End Sub

End Class

On line Print("My message") errors.

[Mumbles0]

Reply to Vadim (re: Multithreading)

I have no idea what your code is trying to do. When you make the call:

Print("My message")

to a sub declared like this:

Public Sub Print(ByVal tLog As TextBox, ByVal Message As String)

this suggests to me that you have a lot more to learn about programming fundamentals. I suggest you concentrate on this before you tackle the very complex area of multithreading.

Step 11 is a “side topic” and was included to illustrate the basic idea of multithreading. This code is not used to access the API.

Multithreading requires very advanced programming and you will run into problems when you try to access controls on the user interface from separate threads. I don’t know much about this subject myself.

[Vadim]

Sort array

The question is closer to the subject. How to sort array MarketPricesCompressed runnerPrices on bestPricesToBack(0) in descending order.
For example:

Original:
Runners      BestPriseToBack(0)
1                           7.7
2                           1.3
3                           5.6

Result:
Runners      BestPriseToBack(0)
1                           7.7
2                           5.6
3                           1.3

[Vreljanski]

Hey Mumbles!

great tutorial and post man I have been reading it for a week now and slowly been building my custom bet angel looking app.

I sucessfully implemented most of the steps you described and i needed them and so far managed to get all suport when i was stuck just from the forums.

Now i am facing one small problem.

I display full market depth for my horse runners but i want to add matched volume for the each price if there was any matching.

and I havent been able to find a way how. I red the docmentations also and didnt figured it out.

Cheers and thanks

also as soon as i catch some time i will post how to definately filter only horse win markets as i saw that is a problem to some ppl.

[Mumbles0]

Reply to Vreljanski (re: Matched Volume)

I think getMarketTradedVolumeCompressed will give you the data you want. This gives you the values shown in the ‘Price’ and ‘Traded’ columns on the ‘Market Information’ page for each runner shown on the website’s page for your market.

This service can be called 60/min on the free API. It’s best to call getMarketTradedVolumeCompressedAsync because this is more efficient.

This call returns a compressed .tradedVolume string which can be unpacked using these classes:

Class RunnerVolumeType
  Public selectionId As Integer
  Public asianLineId As Integer
  Public actualBSP As Double
  Public totalBspBackMatchedAmount As Double
  Public totalBspLiabilityMatchedAmount As Double
  Public tradedVolume As VolumeType()
End Class

Class VolumeType
  Public odds As Double
  Public totalMatchedAmount As Double
End Class

Class UnpackMarketTradedVolumeCompressed
  Public RunnerVolume As RunnerVolumeType() = {}

  Sub New(ByVal TradedVolume As String)
    Dim Tvolume, Part, Field As String(), m, n As Integer

    Tvolume = TradedVolume.Split(":")       'Split data for each runner
    n = UBound(Tvolume) - 1
    ReDim RunnerVolume(n)
    For i = 0 To n    'For each runner
      Part = Tvolume(i + 1).Split("|")
      Field = Part(0).Split("~")
      RunnerVolume(i) = New RunnerVolumeType
      With RunnerVolume(i)
        .selectionId = Field(0)
        .asianLineId = Field(1)
        .actualBSP = Val(Field(2))
        .totalBspBackMatchedAmount = Val(Field(3))
        .totalBspLiabilityMatchedAmount = Val(Field(4))
        m = UBound(Part) - 1
        ReDim .tradedVolume(m)
        For j = 0 To m
          Field = Part(j + 1).Split("~")
          .tradedVolume(j) = New VolumeType
          .tradedVolume(j).odds = Val(Field(0))
          .tradedVolume(j).totalMatchedAmount = Val(Field(1))
        Next
      End With
    Next

  End Sub
End Class

Unpack the returned data by creating a new UnpackMarketTradedVolumeCompressed object, similar to what we've done in steps 10 and 14. A list of odds & traded amounts is returned for each runner in the .tradedVolume array.

Note that no .sortOrder parameter is returned, so you will have to use .selectionId to identify the runner data.

[Mumbles0]

Reply to Vadim (re: Sorting .runnerPrices according to bestBackPrice)

The sort can be done similar to step 17, but using a different comparison method. You require another class to compare the .bestPricesToBack(0) values:

Class CompareBestBack     'A class to allow sorting according to the highest back price
  Implements IComparer(Of BFUK.RunnerPrices)

  Public Function Compare(ByVal x As BFUK.RunnerPrices, ByVal y As BFUK.RunnerPrices) As Integer Implements System.Collections.Generic.IComparer(Of BFUK.RunnerPrices).Compare
    Return bestBack(y) - bestBack(x)
  End Function

  Private Function bestBack(ByVal w As BFUK.RunnerPrices) As Integer
    Return If(w.bestPricesToBack.Length > 0, w.bestPricesToBack(0).price * 100, 0)
  End Function

End Class

There are two things to watch here. If no back bets have been placed on a runner, then .bestPricesToBack(0) will not exist. Function bestBack checks this and returns zero if the bestPricesToBack array is empty, thereby avoiding an exception. Any runner with no back bets will be sorted to the end of the array.

Also, if we compare two close prices (e.g. 2.70 and 2.80) simply by subtracting them, we get 0.10. This will be rounded to 0 by Function Compare because it returns type Integer. This means that runners having close prices could be treated as being equal for the purpose of the sort which would result in an incorrect sort. To avoid this problem we multiply each price by 100 before the subtraction.

To perform the sort add a new line to Sub BetFairUK_getMarketPricesCompressedCompleted:

[COLOR="Gray"].....
  .....
    With oMarketPrices
      Print(.marketId & " " & .marketStatus.ToString & " " & .runnerPrices.Length & " runners")
      'Process returned market prices here.
      [COLOR="Black"]Array.Sort(.runnerPrices, New CompareBestBack)[/COLOR]
      For i = 0 To .runnerPrices.Length - 1
        With .runnerPrices(i)
      .....
    .....
  .....
.....[/COLOR]

[Vadim]

I tried to do it seems, but I failed. Thank you, Membles0

[Dodgee]

Another question about making objects available to other classes

Another newbie question here...

I'm just trying to rearrange things a bit to make my client look better and work more intuitively. I've created a separate login form which is now the startup form. The class for the form handles the login process, performs error handling and, if there is no error, displays the main window and initiates the population of the events/markets treeview.

So now I have two different classes which both need to be able to work with headers to perform their calls, so I need the Checkheader subs and oHeaderUK function to be available to both classes.

What's the best way to achieve this? I tried a few ways: making the required variables, subs and function public and referencing them from the other class; creating a new module and making everything friend or public (like the Unpack modules). However, I either get an error or an empty header which of course leads to a "no session" error from the api when making subsequent calls.

I'm probably missing something simple...

[Mumbles0]

Reply to Dodgee (re: common access)

I prefer to put common variables and procedures into a separate module. If they are declared Friend or Public they will be accessible from all classes and modules in your project. For example the Betfair tester works fine if we relocate these procedures into a new module as shown here:

Module MiscMod

  [COLOR="Black"]Friend[/COLOR] oHeaderGL As New BFGlobal.APIRequestHeader     '<<< Change access to Friend (or Public)

  Function oHeaderUK() As BFUK.APIRequestHeader
    Dim Header As New BFUK.APIRequestHeader
    Header.sessionToken = oHeaderGL.sessionToken
    Return Header
  End Function

  Sub CheckHeader(ByVal Header As BFGlobal.APIResponseHeader)
    With Header
      Print("HeaderCode = " & .errorCode.ToString)
      oHeaderGL.sessionToken = .sessionToken
    End With
  End Sub

  Sub CheckHeader(ByVal Header As BFUK.APIResponseHeader)
    With Header
      Print("HeaderCode = " & .errorCode.ToString)
      oHeaderGL.sessionToken = .sessionToken
    End With
  End Sub

  Sub Print(ByVal Message As String)
    With [COLOR="Black"]TestForm[/COLOR].tLog                              '<<< Nominate the form containing the TextBox.
      .SelectionStart = .Text.Length
      .SelectedText = vbCrLf & Message
    End With
  End Sub

 ...............
 ...............

End Module

Note that a couple of minor changes are required as shown. In a module the access level for the procedures is Friend by default.

You say you’ve tried this but it didn’t work. I’m only guessing, but perhaps you have another oHeaderGL object declared elsewhere (in one of your form classes?). Ensure that there is only one. Also check that none of these procedures exist elsewhere (in your classes).

Keep trying....

[Dodgee]

Problem solved

I found the issue. I figured I was missing something, like forgetting to comment out some other declaration of the oHeaderGL object elsewhere in the code, as you suggested.

It was actually because of the sub that tries to read the session token from a file. I forgot to move this sub (code below) to the start of the login form class, so the first time I ran the app, the login form would work fine but as soon as the main form was loaded, it would try and read the session token from the file, which of course at this point was empty. Hence any subsequent calls resulted in a no session error.

    Private Sub LoginForm2_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        oHeaderGL.sessionToken = My.Computer.FileSystem.ReadAllText(SessTokFile)
    End Sub

[Vreljanski]

Again thankles Mumbles0 for all the help it has been really great to have it all in one discusion and its really valuable resource.

I have further thing to ask. I have seeked trought discussion and found something similar to what i need but it dont help me.

I place bets and when its all done i want to know how much i made or lost on that market.

How do I do that ?

Thanks