Adding Meta to Events?

[digerata]

Working with the library for the first time (I like it a lot!), I ran into a need to provide more information about events. For example:

• Human name (e.g., :submit is "Submit for Approval")
• Role allowed to call event (e.g., only the owner can submit this for approval)

Meta allows me to add info to the state, but both of these items above are at the event level.

I could see a response saying that the role can be checked in the transition event handler. But doing that doesn't help the view that needs to conditionally display the event for a particular role only.

Why not allow :meta to be specified with the event definition? Is there another recommended way to achieve what I need?

[gamov]

you can:

    state :ready, :meta => {:display_name => 'Ready to order'}  do
      event :order, :transitions_to => :ordered
      event :edit, :transitions_to => :composing, meta: {display_name: 'Back to Composing'}
    end

is it what you want?

[digerata]

Yes!

But when I tried to read from it, the meta was blank.

I used instance.current_state.events and did not see any meta available there.

[digerata]

Okay, I found the meta :) I see you have to use:

instance.current_state.events[:event].meta

When creating UI for the different events, this works, but is a bit verbose. Example:

<% @instance.current_state.events.each do |event, str| %>
    <a href="javascript:performEvent('<%= event %>');" class="btn">
        <%= @instance.current_state.events(event).meta[:display_name] %>
    </a>   
<% end %>

Is there a better way?

[geekq]

Looking for less verbose way?

What about assigning to an intermediate variable like

<% possible_events = @instance.current_state.events %>
<% possible_events.each do |event, str| %>
    <a href="javascript:performEvent('<%= event %>');" class="btn">
        <%= possible_events(event).meta[:display_name] %>
    </a>   
<% end %>

[digerata]

Thanks for the tip geek. I'll work within those constraints.

My perspective is: I have the event in the loop, why can't I access other attributes of the event directly? E.g., instead of having access to the symbol and the string of the symbol, (:event => "event") why not make it the object or object hash (:event => event_object)? In this way, you have @instance.current_state[:event].meta or @instance.current_state[:event][:meta]. The resulting code would be:

<% @instance.current_state.events.each do |name, event| %>
    <a href="javascript:performEvent('<%= name %>');" class="btn">
        <%= event.meta[:display_name] %>
    </a>   
<% end %>

I think meta is really powerful and a great idea. In my case, it's not just the display name. I also have roles of who can trigger an event, etc.

[geekq]

instead of having access to the symbol and the string of the symbol, (:event => "event") why not make it the object or object hash

yes, that would be probably a better API. But too late - that change would be not backward compatible - would break people's code.

Could create an additional iterator like event_details.each ... probably someday...

[geekq]

Implementation of #109 now contains a shortcut similar to what you desired. Look at the flat function https://github.com/geekq/workflow/commit/ff471575678bb4e9a7b76246c6ee0cecf8c8a2e7#diff-709316b732f30ee878cb6dabf4ac2482R14 ant it's usage like:

state.events.flat.each do |event|