PHP Class izzum\statemachine\utils\ExternalData
It's main use it for it to be used so an external application
can set data that can be used in a Rule or Command to
check/execute a transition.
This allows us to nicely encapsulate the data so we do not need to do
stuff like checking the $_REQUEST/$_SESSION etc in Rules/Commands during a
statemachine transition.
example:
state A
state B
transition A->B (rule: t>7)
State C
transition A->C (rule: can always take place to 'force' a transition from A
to B
with step C in between. For example when we need to do
a manual transition in the context of a Controller Action)
We want this to be know via the HISTORY of the statemachine and
therefore we have a seperate transition for this
transition C->B (rule: can safely take place)
Now when we use a cronjob where we loop over items the code would be like
this:
pseudocode
$all = $service->getEntityIdsForState('A');
for ($all as $id) do $statemachine->run($id)
end pseudocode
the problem with the code above is that there are two OUTGOING transitions
for state A and that transition A->B might fail because the rule
is not satisfied (for t=4), but then A->C would run since that is
essentially an empty rule.
Note: this is only a problem when we use the 'run' method on the
statemachine. It is not a problem when we use the 'transition' method on the
sm since we provide a transition name to that method, forcing the sm to
execute only that transition if it can. But keep in mind that there are
situations where you would just want the sm to decide what it does by calling
'run' multiple times in a row.
What we need is to be able to set data that is checked in the Rule for
the transition from A->C. This data can be set by the client of the
state machine in exceptional circumstances, to PREVENT the use of empty
rules and to PREVENT unwanted state transitions and to PREVENT difficult
mechanisms for setting data in the client where the rule has to do lots
of work to retrieve it (eg: controller->form->database->rule)
for exmample: \a cron job would not set data and the rule for transition A->B
would
be checked against $t > 7. A controller would set data and the Rule for
transition A->C would be able to run in the context of a controller
that sets data but NOT in the context of the cron
that does not set the contextual data.
example:
controllercode where the statemachine is used:
set context as a flag variable
ExternalData::set(Data::CONTEXT_SOME_VALUE);
$sm->transition('a_to_c');
rule code where the context is checked:
protected function _applies()
{
check external context and act upon it
return ExternalData::get() === Data::CONTEXT_SOME_VALUE;
}
Show file
Open project: rolfvreijdenberger/izzum-statemachine
Class Usage Examples
Public Methods
| Method |
Description |
|
|
clear ( ) |
clear the external context |
|
|
get ( ) : mixed |
get the external data |
|
|
has ( ) : boolean |
is there any external data set? |
|
|
set ( mixed $data = null ) |
set the external data |
|
Method Details
clear()
public static method
clear the external context
get()
public static method
has()
public static method
is there any external data set?
set()
public static method
