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Iterating a dataset in an OnCalc event

edited November 2015 in RAP
Hi,

I want to loop through all values in a RAP dataset linked to the main
dataset and populate the result with all recoords of a specific field,
in this case telephone numbers. RAP seems to know about EOF but it
roesn't recognise Next. So how can I do this.

Or is there another way without even using RAP.

Thanks,

Ken

Comments

  • edited November 2015
    On 18/11/2015 12:21, Ken Randall wrote:

    I wrote my own RAP class for this:

    //MMWIN:CLASSCOPY
    unit _MM_Copy_Buffer_;

    interface

    type
    TnavTppDataPipelineRTTI = class(TraTppDBPipelineRTTI)
    public
    class procedure GetPropList(aClass : TClass; aPropList : TraPropList);
    override;
    class function GetPropRec(aClass : TClass; const aPropName : String;
    var aPropRec : TraPropRec) : Boolean; override;
    class function GetParams(const aMethodName : String) : TraParamList;
    override;
    class function CallMethod(aObject : TObject; const aMethodName :
    String; aParams : TraParamList; aGet : Boolean) : Boolean; override;
    class function GetPropValue(aObject : TObject; const aPropName :
    String; var aValue) : Boolean; override;
    class function RefClass : TClass; override;
    class function SetPropValue(aObject : TObject; const aPropName :
    String; var aValue) : Boolean; override;
    end;


    implementation


    { TnavTppDataPipelineRTTI }

    class function TnavTppDataPipelineRTTI.CallMethod(aObject : TObject;
    const aMethodName : String; aParams : TraParamList; aGet : Boolean) :
    Boolean;
    var
    lPipeline : TppDBPipeline;
    begin

    Result := True;

    lPipeline := TppDBPipeline(aObject);

    if ppEqual(aMethodName, 'First') then
    begin
    TppDataPipelineAccess(lPipeline).First;
    end
    else
    if ppEqual(aMethodName, 'Last') then
    begin
    lPipeline.Last;
    end
    else
    if ppEqual(aMethodName, 'Next') then
    begin
    TppDataPipelineAccess(lPipeline).TraverseBy(1);
    end
    else
    if ppEqual(aMethodName, 'Prior') then
    begin
    TppDataPipelineAccess(lPipeline).TraverseBy(-1);
    end
    else

    Result := inherited CallMethod(aObject, aMethodName, aParams, aGet);
    end;

    class function TnavTppDataPipelineRTTI.GetParams(const aMethodName :
    String) : TraParamList;
    begin
    Result := inherited GetParams(aMethodName);
    end;

    class procedure TnavTppDataPipelineRTTI.GetPropList(aClass : TClass;
    aPropList : TraPropList);
    begin
    inherited GetPropList(aClass, aPropList);

    {add methods}
    aPropList.AddMethod('First');
    aPropList.AddMethod('Last');
    aPropList.AddMethod('Next');
    aPropList.AddMethod('Prior');
    end;

    class function TnavTppDataPipelineRTTI.GetPropRec(aClass : TClass; const
    aPropName : String; var aPropRec : TraPropRec) : Boolean;
    begin
    Result := True;

    if ppEqual(aPropName, 'First') then
    MethodToRec(aPropName, False, aPropRec) else
    if ppEqual(aPropName, 'Last') then
    MethodToRec(aPropName, False, aPropRec) else
    if ppEqual(aPropName, 'Next') then
    MethodToRec(aPropName, False, aPropRec) else
    if ppEqual(aPropName, 'Prior') then
    MethodToRec(aPropName, False, aPropRec) else
    Result := inherited GetPropRec(aClass, aPropName, aPropRec);
    end;

    class function TnavTppDataPipelineRTTI.GetPropValue(aObject : TObject;
    const aPropName : String; var aValue) : Boolean;
    begin
    Result := inherited GetPropValue(aObject, aPropName, aValue);
    end;

    class function TnavTppDataPipelineRTTI.RefClass : TClass;
    begin
    Result := inherited RefClass;
    end;

    class function TnavTppDataPipelineRTTI.SetPropValue(aObject : TObject;
    const aPropName : String; var aValue) : Boolean;
    begin
    Result := inherited SetPropValue(aObject, aPropName, aValue);
    end;

    initialization
    raUnregisterRTTI(TraTppDBPipelineRTTI);
    raRegisterRTTI(TnavTppDataPipelineRTTI);

    finalization

    raUnregisterRTTI(TraTppDBPipelineRTTI);
    raRegisterRTTI(TnavTppDataPipelineRTTI);


    end.
  • edited November 2015
    Hi Ken,

    The solution Paul gave is a great example of extending the RAP RTTI.

    It is also possible to create a RAP pass-thru function to perform the
    same task. You could create a pass-thru function named
    PipelineNext(aPipeline), which takes the DataPipeline as a parameter and
    then calls .Next in Delphi. See the RAP demos for examples of pass-thru
    functions.

    I'm however a bit unclear about what you are trying to accomplish. Do
    you wish to populate a TppVariable with all the phone numbers in the
    dataset? If you would like to display all records in a field, why not
    just connect that dataset to a subreport and have it iterate through the
    dataset for you?

    Best Regards,

    Nico Cizik
    Digital Metaphors
    http://www.digital-metaphors.com
  • edited November 2015
    Thanks, Nico,

    That is what I have now done.

    Ken

  • edited November 2015
    Thanks Paul.

  • edited November 2015
    On 18/11/2015 15:15, Nico Cizik (Digital Metaphors) wrote:

    Yes, I created my RAP RTTI class because I wanted to get info and store
    it in a structure BEFORE the report prints so that I could make
    decisions about whether to display groups etc in advance.
  • edited November 2015
    The problem with using a subreport is that when report is exported to
    Excel the contents of the subreport are not included. My subreport is a
    child report. Is there a way to do this?

  • edited November 2015
    Hi Ken,

    For XlsReport all elements are exported.

    For XlsData the default behavior is main report detail elements are
    exported. Use the File | Print To File Setup dialog to specify which bands
    and component to export. For a subreport, access the workspace for the
    childreport and use the File | Print To File Setup dialog from there.

    Check out the RBuilder Help topics for TppXlsReportDevice and
    TppXlsDataDevice for more details on using these devices.




    Best regards,

    -
    Nard Moseley
    Digital Metaphors
    www.digital-metaphors.com

    Best regards,

    Nard Moseley
    Digital Metaphors
    www.digital-metaphors.com
This discussion has been closed.