Title: Extract field from DataSet into TStringList
Question: 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.
Answer:
{-----------------------------------------------------------------------------
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.