Use function on a DataModule

Question

I have a datamodule (TfDB) I wanted to add this function to it

 Function GetZone(zone :string):string;

When i try to run it i get this error... Unsatisfied forward of external declaration : TfDB.GetZone

unit MyDataModule;

interface

uses
  System.SysUtils, System.Classes, Data.DB, Data.Win.ADODB;

type
  TfDB = class(TDataModule)
    dbconnection: TADOConnection;
  private
    { Private declarations }
  public
          Function GetZone(zone :string):string;
  end;

var
  fDB: TfDB;

implementation

{%CLASSGROUP 'System.Classes.TPersistent'}

{$R *.dfm}

  Function GetZone(zone:string):string;
  begin
  if zone = 'FLayout1' then
        result := '1';
  if zone = 'FLayout2' then
      result := '2';
  if zone = 'FLayout3' then
      result := '3';
  if zone = 'FLayout4' then
      result := '4' ;
  if zone = 'FBoneYard' then
      result := 'BoneYard';
  if zone = 'FShop' then
      result := 'shop';
  if zone = 'FMisc' then
      result := 'Misc' ;
  end;

end.

Answer 1

In the implementation section you need to declare the function as being a method of the class:

function TfDB.GetZone(zone:string):string;
begin
  ....
end;

Your declaration looked like this:

function GetZone(zone:string):string;
begin
  ....
end;

And that defines a stand-alone function rather than a method of the class.