To Extract a specific field from a dataset in a TStringList. Useful for
populating TlistBoxes that you dont want to be data aware etc...

Also has a handy lookup method.

Nice and quick and easy.

{-----------------------------------------------------------------------------

 Unit Name: unitDatasetExtract1



 Creation Date: 04/06/02 00:39:21

 Documentation Date: 04/06/02 00:39:21

 Release Date: 15 Jan 2003

 Version: 1.0



 Author: Stewart Moss



 Compiler version:

   Delphi 5 and Delphi 6 tested



 Purpose:

  To Extract a specific field from a dataset in a TStringList. Useful for

  populating TlistBoxes that you dont want to be data aware etc...

  (Released originally on Delphi3000.com)



 Description:

        At the moment it only support TStringLists but it will convert

        most TField.FieldType into a string



 Notes:



  How to use

  ----------

   var

    DE : TDatasetExtract;

    tsl : TStringList;

    CustId : string;



   begin

     de := TDatasetExtract.create;

     tsl := TStringList.create;



     with de do

     begin

      dataset := Query1;

      FieldName := 'CustomerName';

      tsl := de.strings;

     end;              // with



     // Now we have a TStringList containing all the Customer names

     // which we can populate listboxes and other yummy stuff



     // or lets perform a lookup returning the customer ID knowing the Customer Name



     CustID := de.QuickSearch('CustomerName','Stewart Moss','CustomerID',[loCaseInsensitive]);



     de.free;

     tsl.free;





   end;







 Dependancies:



 History:



          Copyright 2002 by Stewart Moss

          All rights reserved.

          You must not modify this Unit Header.

-----------------------------------------------------------------------------}



unit unitDatasetExtract1;



interface



uses classes, db{$IFDEF VER140}, variants{$ENDIF};



type

  TDatasetExtract = class

  private

    fDataset: TDataset;

    fStrings: TStringList;

    fFieldname: string;

    fEmptyNulls: boolean;

    fappend: string;

    fprepend: string;



    function FieldToString(Field: TField): string;

    procedure ExtractStringList;



    function Get_Strings: TStringList;

    procedure Set_Dataset(const Value: TDataset);



  public

    constructor create;

    destructor destroy; override;



    function quickSearch(searchField,

      searchValue, ReturnField: string; Locateoptions: TLocateOptions): string;



  published



    property append: string read fappend write fappend;

    property prepend: string read fprepend write fprepend;

    // You have the option of appending and prepending any information

    // to the begining of each record.

    // Useful for creating delimited records easily (ie you can just add the StringList

    // items together) (maybe not really that useful :P )



    property EmptyNulls: boolean read fEmptyNulls write fEmptyNulls;

    // Whether or not nulls must be translated into blank values,

    // or ignored



    property FieldName: string read fFieldname write fFieldname;

    property Dataset: TDataset read fDataset write Set_Dataset;



    property Strings: TStringList read Get_Strings;

  end;



implementation



{ TDatasetExtract }



constructor TDatasetExtract.create;

begin

  FDataset := nil;

  fstrings := TStringlist.create;

  emptynulls := true;

end;



destructor TDatasetExtract.destroy;

begin

  fstrings.free;

  inherited;

end;



procedure TDatasetExtract.ExtractStringList;

var

  field: tfield;

begin

  fstrings.clear;

  with fdataset do

  begin

    try

      disablecontrols;

      First;

      while not eof do

      begin

        field := FieldByName(FFieldname);

        if not varisnull(field.asvariant) then

          fstrings.add(Fprepend + FieldToString(Field) + Fappend) else

          if emptyNulls then

            fstrings.add(fprepend + fappend);

        next;

      end; // while

    finally

      first;

      enablecontrols;

    end; // finally

  end; // with

end;



function TDatasetExtract.FieldToString(Field: TField): string;

begin

  result := field.AsString;

end;



function TDatasetExtract.Get_Strings: TStringList;

begin

  if (fdataset <> nil) and (ffieldname <> '') then

    extractStringList;

  Result := fStrings;

end;



function TDatasetExtract.quickSearch(searchField,

  searchValue, ReturnField : string; Locateoptions: TLocateOptions): string;

{-----------------------------------------------------------------------------

  Procedure: TDatasetExtract.quickSearch

  Author:    StewartM

  Arguments: searchField, searchValue, ReturnField : string; Locateoptions: TLocateOptions

  Result:    string



  Searches for a field value in a specified field name and returns the specified field

  returns '' is nothing is found



  eg

    Ask for a customer id of 10 and return the customer name

-----------------------------------------------------------------------------}

begin

  with fdataset do

  begin

    DisableControls;

    try

      result := '';

      if not locate(searchfield, searchvalue, locateoptions) then

        exit;

      result := fieldbyname(ReturnField).asstring;

    finally

      first;

      enablecontrols;

    end;

  end;

end;



procedure TDatasetExtract.Set_Dataset(const Value: TDataset);

begin

  fDataset := Value;

end;



end.