[Workflow] Add documentation for the Workflow Component

[lyrixx]

Hi!

symfony/symfony#11882 is finally merged.
So the next step is to document this component + the integration into the FrameworkBundle.

But I'm really not good enough to achieve this task BUT I'm 100% available for helping anyone with that.
I created this little app to show how it works in action and there is also this french presentation.

[Nyholm]

I can have a look at this at the beginning of August. If anyone is interested to start before that just write on this issue.

I will write a comment when I actually begin.

[Nyholm]

I've started on a PR now

[xabbuh]

#6871 is merged now. However, there is some late feedback we may want to talk about. That's why I decided not to close here.

[rmasclef]

Hi !

I noticed that there is no documentation about the the behavior of the workflow component when we do not set a marking_store.

When we take a look at @lyrixx demo (https://github.com/lyrixx/SFLive-Paris2016-Workflow), we can see that he do not set the type and the marking_store in his configuration. But there is a marking property in the supports object ...

Perhaps it will be good to add these default values in the doc ?

I noticed another thing concerning the behavior of the workflow component with the supports object:

If we take a look at this example:

config.yml

framework:
    workflows:
        request_for_operation:
            type: 'state_machine'
            marking_store:
                type: 'single_state'
                arguments:
                    - 'status'
            supports:
                - AppBundle\Entity\RequestForOperation
            places:
                - draft
                - pending_for_management
                - in_progress
                - finished
                - canceled
            transitions:
                save:
                    from: draft
                    to:   pending_for_management
                track:
                    from: pending_for_management
                    to:   in_progress
                close:
                    from: in_progress
                    to:   finished
                cancel:
                    from: [pending_for_management, in_progress]
                    to:   canceled

RequestForOperation.php

class RequestForOperation
{
    /**
     * @ORM\Column(name="status", type="string", nullable=true)
     */
    private $status;
    
    ...
}

The initial place seems to be draft.

On a RequestForOperation creation, is the status automatically set to draft ? or is this draft place not really "existing" (i.e status = null) ?

[lyrixx]

On a RequestForOperation creation, is the status automatically set to draft ? or is this draft place not really "existing" (i.e status = null) ?

If you do $r = new RequestForOperation the status will be null. You have to set it to draft yourself.
But if you don't, as soon as $r pass through the Workflow the value will be set to draft for your.

I.E: there is not magie in this component ;)