Web Action component with save-state property and behavior.

All web action components can be invoked by name from WebHub HTML, e.g. (~WebAction1.execute~).

Use TwhWebActionEx as-is, or base your own custom classes on it.

When you call an action component by name using WebHub macro syntax, you are calling its Execute method. Performance is faster if you say (~webaction1.execute~) than if you omit the .execute method name. Regardless, this gives you an extremely powerful way to extend WebHub's capabilities. Any action that you want to call from the web can be triggered in this way. You can start your testing by using the TwhWebActionEx component on the palette, and if/when you want to take the next step, you can build your own custom component. There are many examples with source code in the webhub\lib directory that you may model.

An action component has a tpUpdated property which tells you whether it is ready, and a Test property which invokes the doUpdate method -- enabling full functionality in the Delphi IDE as well as at run-time. These verbs of Test and Update also appear within the TtpActionList associated with the component, and on the TtpVerbBar.

Simple 'hello' Example

procedure TfmAppSendStr.webAction1Execute(Sender: TObject);
begin
  inherited;
  // this code will run when (~webaction1.execute~) is called.
  with TwhWebAction(Sender).Response do 
  begin
    SendHdr('2','Welcome');
    Send('Enter any string here...');  // It is ok to use parentils to reference droplets here.
  end;
end;

Working with Parameters

WebHub v1.49+ stores the parameter in the HtmlParam property. Here is how you would access the data within the OnExecute event handler, in this case to print the data in uppercase and bold.

procedure TfmAppSendStr.webAction1Execute(Sender: TObject);
var
  a1:string;
begin
  inherited;
  with TwhWebAction(Sender).Response do 
  begin
    a1:=uppercase(HtmlParam);
    Send('<b>'+a1+'</b>');
  end;
end;

Working with Command Strings

The following list itemizes how a command string can be made available to a TwhWebActionEx component:

1. Any command string on the URL will be stored in TwhApplication.Command. (Advanced note: to handle multiple command strings passed to multiple executions of the same TwhWebActionEx component within a page, see the TtpAction.RemoveCommandPortion method.)

2. Any command string on the URL that has the component name as a prefix, e.g. ?AppID:PageID:Session:ComponentName.Command, will be included in TwhApplication.Command and will be set as TwhWebActionEx.Command. The TwhWebActionEx.OnSetCommand event handler is called in this case.

3. Any command string on the URL that has no component name prefix is considered global to all TwhWebActions executed within the page, e.g. ?AppID:PageID:Session:Command. Such a command string will be stored in TwhApplication.Command and in TwhWebActionEx.Command, and the OnSetCommand event handlers will be called accordingly.

4. Any command string passed to the component in W-HTML using this syntax: %=webaction1.command=% where the dot ('.') separates the name of the component from the command string.

When to use a TwhWebActionEx component

1. You have a place to put initialization code (onUpdate), independent of the action code (onExecute)
2. If you later decide to make the functionality generic by building your own web action component, you will be much closer to the correct coding style
3. You do not have to itemize anything under TwhApplication.events

Events

• onUpdate -- called at least once when the components update themselves when the WebApp starts
• onSetCommand -- called when the Command property is set
• onExecute -- called just before the component executes