Using VB2008 to acccess the Betfair API: A tutorial

[ribogio7]

Thanks a lot Mumbles0.

Right Code is here.

Dim oGBHReq As New BFExchange.GetBetHistoryReq
        Dim oGBHResp As New BFExchange.GetBetHistoryResp

        With oGBHReq
            .header = oHeaderUK
            .placedDateFrom = Now.AddDays(-7)
            .placedDateTo = Now
            .startRecord = 0
            .recordCount = 30
            .betTypesIncluded = BFExchange.BetStatusEnum.S 
            ReDim .eventTypeIds(0) : .eventTypeIds(0) = 1 'For soccer
            ReDim .marketTypesIncluded(0) : .marketTypesIncluded(0) = BFExchange.MarketTypeEnum.O
            .sortBetsBy = BFExchange.BetsOrderByEnum.PLACED_DATE
        End With

What's the difference between BFExchange.MarketTypeEnum.O,L,R,A...?

ps: Keep up the good work Mumbles0.

[Mumbles0]

Market types

O, L, R, A refer to the different type of markets offered by Betfair (Odds, Line, Range & Asian handicap).

Some info is given in the Betfair help here.

[waldjunge]

BFUK.MarketStatusEnum.ACTIVE Error?

I get sometimes a "Null reference exception Error" in the line 'If .marketPrices.marketStatus = BFUK.MarketStatusEnum.ACTIVE Then'
Anybody knows why?

  Sub findBestPrice4Betting(ByVal MpriceResp As BFUK.GetMarketPricesResp, ByVal horse2searchID As Integer, ByVal BackOrLay As String)
        Dim Back As String

        myFoundPrice = 0
        With MpriceResp
            CheckHeader(.header)   'OK
            'print6(TimeString & " Single Horse Price -> " & .errorCode)
            If .marketPrices.marketStatus = BFUK.MarketStatusEnum.ACTIVE Then
                If .errorCode = BFUK.GetMarketPricesErrorEnum.OK Then
                    With .marketPrices
                        For i = 0 To .runnerPrices.Length - 1

[Mumbles0]

Null reference exception

waldjunge,

It look like you are getting an API error. If so, the response object property.marketPrices is not set (i.e. is set to Nothing). This causes the “Null Reference Exception”. You should always ensure that .errorCode = OK before accessing the .marketPrices object.

To fix this, swap the two If statements over in your code:

  If .errorCode = BFUK.GetMarketPricesErrorEnum.OK Then
   If .marketPrices.marketStatus = BFUK.MarketStatusEnum.ACTIVE Then
     With .marketPrices
        .......

If you look at the .errorCode in the response header you will see what's causing the API error.

[glenn1000]

Hi there sorry to bother you but i am new here.
the tuts where great thanks.has anyone got a piece of code to parse the compressed data for vb2008 or a quick breakdown of the info in the compressed code so i can try ?? to parse it myself.

cheers glenn

[waldjunge]

thanks a lot Mumbles0!

[waldjunge]

I get the error message "Index our of Array" in line:

With .bestPricesToLay(i)

How big is the index of the array .bestPricesToLay(i) ? Is this index=number of runners? For example 12 runners -> .bestPricesToLay(12)
Or is index=number of Odds? Means this index can have a maximum of 2 (0,1,2)-> .bestPricesToLay(2) ?

So .bestPricesToLay(number of runners) is wrong?

 Sub findBestPrice4Betting(ByVal MpriceResp As BFUK.GetMarketPricesResp, ByVal horse2searchID As Integer, ByVal BackOrLay As String)
        Dim Back As String
        Dim indexI As Long = 0

        myFoundPrice = 0
        With MpriceResp
            CheckHeader(.header)   'OK
            'print6(TimeString & " Single Horse Price -> " & .errorCode)
            '  
            If .errorCode = BFUK.GetMarketPricesErrorEnum.OK Then
                If .marketPrices.marketStatus = BFUK.MarketStatusEnum.ACTIVE Then
                    With .marketPrices
                        For i = 0 To .runnerPrices.Length - 1
                            With .runnerPrices(i)
                                horse2Find = .selectionId
                                'print6(TimeString & " Find -> " & horse2searchID & " = " & .selectionId & "   ->" & .bestPricesToBack(0).price) '& " " & .bestPricesToBack(1).price)
                                Back = ""
                                '   For j = 0 To .bestPricesToBack.Length - 1
                                If BackOrLay = "B" Then
                                    With .bestPricesToBack(i)
                                        If horse2Find = horse2searchID Then
                                            einzelhorse(i)
                                            If horseName2Bet = "ERROR" Then einzelhorse(i)
                                            If horseName2Bet = "ERROR" Then einzelhorse(i)
                                            myFoundPrice = .price
                                            amountAvailableOnHorse = .amountAvailable
                                        End If

                                    End With
                                End If
                            End With
                        Next i
                    End With

                    With .marketPrices
                        For i = 0 To .runnerPrices.Length - 1
                            With .runnerPrices(i)
                                horse2Find = .selectionId
                                If BackOrLay = "L" Then
                                    With .bestPricesToLay(i)
                                        If horse2Find = horse2searchID Then
                                            einzelhorse(i)
                                            If horseName2Bet = "ERROR" Then einzelhorse(i)
                                            If horseName2Bet = "ERROR" Then einzelhorse(i)
                                            myFoundPrice = .price
                                            amountAvailableOnHorse = .amountAvailable
                                        End If
                                    End With
                                End If
                            End With
                        Next i
                    End With
                End If
            End If
        End With
    End Sub

[Mumbles0]

bestPrices arrays

Yes, bestPricesToLay(number of runners) is wrong.

The maximum length of the .bestPricesToBack and .bestPricesToLay arrays is 3, with the best price in element 0. These arrays hold the 3 best available prices for each runner. These prices are the same as those shown on the web page for the market.

[Mumbles0]

Reply to glen1000 (Re: Compressed responses)

The tutorial has covered parsing (unpacking) the compressed data responses for these calls:

Step 6 - getAllMarkets
Step 10 - getCompleteMarketPricesCompressed
Step 14 - getMarketPricesCompressed
Step 24 - getMarketTradedVolumeCompressed

The Sports API Guide provides details of the compressed data returned by each call.

[Monairda]

Processing data from more than 2 async calls.

Hi Mumbles

I'll follow this steps and works perfect!! Thanks

Monairda,

Perhaps your problem is when to process the data from the 2 responses. This is what I do:
Define a call counter to count the responses, clear it, the send the 2 async requests:

[COLOR="Gray"]Private oMarketPrices As UnpackMarketPricesCompressed
Private oTradedVolume As UnpackMarketTradedVolumeCompressed
[COLOR="Black"]Private CallCount As Integer[/COLOR]

Private Sub GetMarketData()    'Sub to send the requests
  [COLOR="Black"]CallCount = 0  'Clear the call count
  [I]Call getMarketPricesCompressedAsync (as per step 14)[/I]
  [I]Call getMarketTradedVolumeCompressedAsync (as per step 24)[/I][/COLOR] 
End Sub[/COLOR]

The API now sends back the 2 responses. Problem is we don’t know which one comes back first, so we count them in the event handlers. When both responses have been received CallCount = 2, so now we call a sub to process the 2 unpacked data objects.

[COLOR="Gray"]Private Sub BetfairUK_getMarketPricesCompressedCompleted(ByVal sender As Object, ByVal e As BFUK.getMarketPricesCompressedCompletedEventArgs) Handles BetfairUK.getMarketPricesCompressedCompleted
  .........
  [I](Code similar to Step 14)[/I]
  .........
  If .errorCode = BFUK.GetMarketPricesErrorEnum.OK Then
    oMarketPrices = New UnpackMarketPricesCompressed(.marketPrices)   'Unpack the market prices data
    [COLOR="Black"]CallCount += 1    'Count this response
    If CallCount = 2 Then BuildDataTable()   'Process responses when both received[/COLOR]
  End If
  .........
  .........
End Sub

Private Sub BetfairUK_getMarketTradedVolumeCompressedCompleted(ByVal sender As Object, ByVal e As BFUK.getMarketTradedVolumeCompressedCompletedEventArgs) Handles BetfairUK.getMarketTradedVolumeCompressedCompleted
  ........
  [I](Code similar to Step 24)[/I]
  ........
  If .errorCode = BFUK.GetMarketTradedVolumeCompressedErrorEnum.OK Then
    oTradedVolume = New UnpackMarketTradedVolumeCompressed(.tradedVolume)  'Unpack the traded volume data
    [COLOR="Black"]CallCount += 1  'Count this response
    If CallCount = Ncalls Then BuildDataTable()  'Process responses when both received[/COLOR]
  End If
  .........
  .........
End Sub

[COLOR="Black"]Private Sub BuildDataTable()
  [I]Builds a data table from data contained in oMarketPrices and oTradedVolume objects[/I]
End Sub[/COLOR][/COLOR]

Sub BuildDataTable is only called once, from the event handler which handles the second response (whichever that is). This ensures that both responses have arrived before output processing commences.

This is the BuildDataTable:

Private Sub BuildDatatable()
        Dim TablaOddTradedVolumen As New DataTable
        TablaOddTradedVolumen.Columns.Add("Marketid")
        TablaOddTradedVolumen.Columns.Add("SelectionId")
        TablaOddTradedVolumen.Columns.Add("OddBack")
        TablaOddTradedVolumen.Columns.Add("OddLay")
        TablaOddTradedVolumen.Columns.Add("LPM")
        TablaOddTradedVolumen.Columns.Add("Vol")
        TablaOddTradedVolumen.Columns.Add("AmountBack")
        TablaOddTradedVolumen.Columns.Add("AmountLay")
        TablaOddTradedVolumen.Columns.Add("TotalBack")
        TablaOddTradedVolumen.Columns.Add("TotalLay")
        

        Dim market As Integer
        Dim ofila As DataRow
        Dim seleccion As Integer
        Dim back As Decimal
        Dim totalback As Decimal
        Dim totallay As Decimal
        Dim totalvolumen As Decimal

        With oMarketPrices
            market = .marketId
            'Process returned market prices here.
            For i = 0 To .runnerPrices.Length - 1
                With .runnerPrices(i)
                    ofila = TablaOddTradedVolumen.NewRow
                    ofila("Marketid") = market
                    ofila("SelectionId") = .selectionId
                    ofila("Vol") = .totalAmountMatched
                    ofila("lPM") = .lastPriceMatched
                    ofila("Oddback") = .bestPricesToBack(0).price
                    ofila("Amountback") = .bestPricesToBack(0).amountAvailable
                    ofila("Oddlay") = .bestPricesToLay(0).price
                    ofila("Amountlay") = .bestPricesToLay(0).amountAvailable
                    TablaOddTradedVolumen.Rows.Add(ofila)
                    seleccion = .selectionId.ToString
                    back = .bestPricesToBack(0).price
                    totalback = 0
                    totallay = 0
                    totalvolumen = 0
                End With
                [COLOR="red"]
                'I walk the object oTradedVolume for each object oMarket.
                'It's a bit slow but I have not found another way to do
                [/COLOR]
                With oTradedVolume  'Process the unpacked data
                    For t = 0 To .RunnerVolume.Length - 1   'For each runner
                        With .RunnerVolume(t)
                            
                            For j = 0 To .tradedVolume.Length - 1  'Print the table of odds and amounts matched
                                If seleccion = .selectionId Then
                                    If back <= .tradedVolume(j).odds Then
                                        totalback = totalback + .tradedVolume(j).totalMatchedAmount
                                    Else
                                        totallay = totallay + .tradedVolume(j).totalMatchedAmount
                                    End If
                                    totalvolumen = totalvolumen + .tradedVolume(j).totalMatchedAmount
                                End If

                                
                            Next
                            ofila("totalback") = totalback
                            ofila("totallay") = totallay
                            
                        End With
                    Next
                End With
            Next
        End With
        gvPrices.DataSource = TablaOddTradedVolumen
        gvPrices.Refresh()
    End Sub

Do not know how to proceed to the next problem. The routine works perfectly to call a market and control the data of the two asynchronous calls. But how I can do to control the answers when applying for various markets and we have more than two async calls?


Thank you very much

[Mumbles0]

Handling async calls for multiple markets

Monairda,

There are many ways to handle multiple markets. Here is an approach which uses a separate form for each market of interest using common async call handlers.

For this, add a new form to the project. Name it MarketForm. Add your DataGridView control (gvPrices), plus any other controls you may require for the market data. The code for this form is this:

Public Class MarketForm

  Friend MarketId As Integer     'The MarketId for this form
  Friend CallCount As Integer    'The call counter
  Private oMarketPrices As UnpackMarketPricesCompressed
  Private oTradedVolume As UnpackMarketTradedVolumeCompressed

  Friend Sub MarketPricesReceived(ByVal _MarketPrices As UnpackMarketPricesCompressed)
    oMarketPrices = _MarketPrices    'Save the unpacked market prices object
    CallCount += 1                      'Count this response
    If CallCount = 2 Then BuildDatatable() 'Process responses when both received
  End Sub

  Friend Sub TradedVolumeReceived(ByVal _TradedVolume As UnpackMarketTradedVolumeCompressed)
    oTradedVolume = _TradedVolume   'Save the unpacked traded volume object
    CallCount += 1                     'Count this response
    If CallCount = 2 Then BuildDatatable() 'Process responses when both received
  End Sub

  Private Sub BuildDatatable()
   [I]Builds a data table from data contained in oMarketPrices and oTradedVolume objects [/I]
  End Sub

  Private Sub MarketForm_FormClosing(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
    MainForm.MyMarkets.Remove(MarketId.ToString)  'Remove this market from the collection
  End Sub

End Class

Your main form (which I’ve called MainForm) will have facilities to enter the markets you want.

Add the MyMarkets collection object and Sub ShowMarket to the MainForm code. For each market of interest you must call Sub ShowMarket with the MarketId.

  
Public Class MainForm

  Friend MyMarkets As New Collection  'The markets of interest

  Private Sub ShowMarket(ByVal MarketId As Integer)
    Dim Key As String = MarketId   'Use MarketId for the collection key

    If MyMarkets.Contains(Key) Then  'MarketForm exists for this market
      MyMarkets(Key).BringToFront()  'Display it

    Else  'Create a new MarketForm for this market
      Dim Market As New MarketForm   'The new form
      With Market
        .MarketId = MarketId    'Assign the MarketId
        .Text = "Market " & MarketId   'Set the caption
        .Show()    'Show the new MarketForm

        [I]Other MarketForm initialization if required[/I]

      End With
      MyMarkets.Add(Market, Key)  'Add this form to the collection

    End If
  End Sub


  [I]Other code on the main form
  ............
  ............[/I]

End Class

When ShowMarket is called with a new MarketId, a new form is launched, so you will have a separate MarketForm for each market. The MyMarkets collection object keeps track of the markets and holds a list of the MarketForms currently open. If you close a MarketForm, its reference is removed from the collection (by the FormClosing event handler).

Test this to make sure it works OK, then add the code to call the API. (Put this code in MainForm.)

Private Sub GetMarketData()
    Dim Market As MarketForm

    For Each Market In MyMarkets

      Market.CallCount = 0  'Clear the call counter

      Dim oMPCreq As New BFUK.GetMarketPricesCompressedReq
      With oMPCreq
        .header = oHeaderUK()
        .marketId = Market.MarketId   
      End With
      StateCount += 1
      BetfairUK.getMarketPricesCompressedAsync(oMPCreq, StateCount)  'Call the API

      Dim oMTVCReq As New BFUK.GetMarketTradedVolumeCompressedReq      'The request object
      With oMTVCReq
        .header = oHeaderUK()
        .marketId = Market.MarketId      
      End With
      StateCount += 1
      BetfairUK.getMarketTradedVolumeCompressedAsync(oMTVCReq, StateCount)    'Call the API

    Next

  End Sub

  Private Sub BetfairUK_getMarketPricesCompressedCompleted(ByVal sender As Object, ByVal e As BFUK.getMarketPricesCompressedCompletedEventArgs) Handles BetfairUK.getMarketPricesCompressedCompleted
    Try
      If Not e.Cancelled Then
        With e.Result
          CheckHeader(.header)
          If .errorCode = BFUK.GetMarketPricesErrorEnum.OK Then

            Dim oMarketPrices As New UnpackMarketPricesCompressed(.marketPrices)  'Unpack the prices
            Dim Key As String = oMarketPrices.marketId    'The key for this market
            If MyMarkets.Contains(Key) Then                'The MarketForm is open
              Dim Market As MarketForm = MyMarkets(Key)     'A reference to the form for this market
              Market.MarketPricesReceived(oMarketPrices)   'Process the prices response
            End If

          Else
            Print("ErrorCode = " & .errorCode.ToString)
          End If
        End With
      End If
    Catch ex As ApplicationException
      Print(ex.Message)
    End Try

  End Sub

  Private Sub BetfairUK_getMarketTradedVolumeCompressedCompleted(ByVal sender As Object, ByVal e As BFUK.getMarketTradedVolumeCompressedCompletedEventArgs) Handles BetfairUK.getMarketTradedVolumeCompressedCompleted
    Try
      If Not e.Cancelled Then
        With e.Result
          CheckHeader(.header)
          If .errorCode = BFUK.GetMarketTradedVolumeCompressedErrorEnum.OK Then

            Dim oTradedVolume As New UnpackMarketTradedVolumeCompressed(.tradedVolume)  'Unpack the traded volumes
            Dim Key As String = .marketId           'The key for this market
            If MyMarkets.Contains(Key) Then            'The MarketForm is open
              Dim Market As MarketForm = MyMarkets(Key)   'A reference to the form for this market
              Market.TradedVolumeReceived(oTradedVolume)  'Process the volume response
            End If 
           
          Else
            Print("ErrorCode = " & .errorCode.ToString)
          End If
        End With
      End If
    Catch ex As ApplicationException  'If problem
      Print(ex.Message)
    End Try

  End Sub

Sub GetMarketData would typically be called from a Timer Tick event at regular intervals.

As before, it clears the call counter, then makes async calls to getMarketPricesCompressed and getMarketTradedVolumeCompressed, but this process is now in a For Each... loop and is executed for each MarketForm in the collection. Note that we now have a separate call counter for each market.

The responses can be returned by the API in any order. The handlers check the integrity of each response and, if OK, unpack the data. By looking at the MarketId parameter in the received data, the handlers determine which MarketForm the data is intended for and call the appropriate MarketPricesReceived or TradedVolumeReceived methods. As before, these methods use CallCount to ensure that the Sub BuildDataTable is only called after both responses have been received for this market.

[Monairda]

Thank you very much Mumbles0.
I'll try it!!

[Monairda]

Hello Mumbles0

Thank you very much for being our source of wisdom.
The solution works perfectly!!

[waldjunge]

I get a "TargetInvocation Exception" error when running this code. I think it has something to do with StateCount. The declaration should be an object, but it is an Integer!?

Any idea?
Thanks, Martin

 
Private StateCount As Integer    'The unique state object

Private Sub bGetMPricesComp_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ccc.Click
        'Print("*** MarketPricesCompressed ****")

        Dim oMPCreq As New BFUK.GetMarketPricesCompressedReq

        With oMPCreq
            .header = oHeaderUK()
            .marketId = 101431014   'an active market ID
        End With
        StateCount += 1
        BetFairUK.getMarketPricesCompressedAsync(oMPCreq, StateCount) 'Call the API
    End Sub

[Mumbles0]

User state object

waldjunge,

The code you've shown that calls getMarketPricesCompressedAsync is as per Step 14. There is nothing wrong with this. If you are getting an exception it must be caused by something else.

It's OK to use an integer (or any other data type) where an argument of type object is required.

Here we use the incrementing StateCount integer variable to provide a simple unique UserState object that .NET requires if there is more than one outstanding (concurrent) async request.

The UserState parameter can be any object you like, provided it is unique (whatever that means - it is not clearly stated in the documentation). This object comes back to you in the response and can be used for your convenience, for example to identify the request that initiated the response.