README
¶
Transition
Transition is a Golang state machine implementation.
it can be used standalone, but it integrates nicely with GORM models. When integrated with GORM, it will also store state change logs in the database automatically.
Usage
Enable Transition for your struct
Embed transition.Transition into your struct, it will enable the state machine feature for the struct:
import "github.com/qor/transition"
type Order struct {
ID uint
transition.Transition
}
Define States and Events
var OrderStateMachine = transition.New(&Order{})
// Define initial state
OrderStateMachine.Initial("draft")
// Define a State
OrderStateMachine.State("checkout")
// Define another State and what to do when entering and exiting that state.
OrderStateMachine.State("paid").Enter(func(order interface{}, tx *gorm.DB) error {
// To get order object use 'order.(*Order)'
// business logic here
return
}).Exit(func(order interface{}, tx *gorm.DB) error {
// business logic here
return
})
// Define more States
OrderStateMachine.State("cancelled")
OrderStateMachine.State("paid_cancelled")
// Define an Event
OrderStateMachine.Event("checkout").To("checkout").From("draft")
// Define another event and what to do before and after performing the transition.
OrderStateMachine.Event("paid").To("paid").From("checkout").Before(func(order interface{}, tx *gorm.DB) error {
// business logic here
return nil
}).After(func(order interface{}, tx *gorm.DB) error {
// business logic here
return nil
})
// Different state transitions for one event
cancellEvent := OrderStateMachine.Event("cancel")
cancellEvent.To("cancelled").From("draft", "checkout")
cancellEvent.To("paid_cancelled").From("paid").After(func(order interface{}, tx *gorm.DB) error {
// Refund
}})
Trigger an Event
// func (*StateMachine) Trigger(name string, value Stater, tx *gorm.DB, notes ...string) error
OrderStatemachine.Trigger("paid", &order, db, "charged offline by jinzhu")
// notes will be used to generate state change logs when works with GORM
// When using without GORM, just pass nil to the db, like
OrderStatemachine.Trigger("cancel", &order, nil)
OrderStatemachine.Trigger("cancel", &order, db)
// order's state will be changed to cancelled if current state is "draft"
// order's state will be changed to paid_cancelled if current state is "paid"
Get/Set State
var order Order
// Get Current State
order.GetState()
// Set State
order.SetState("finished") // this will only update order's state, won't save it into database
State change logs
When working with GORM, Transition will store all state change logs in the database. Use GetStateChangeLogs to get those logs.
// create the table used to store logs first
db.AutoMigrate(&transition.StateChangeLog{})
// get order's state change logs
var stateChangeLogs = transition.GetStateChangeLogs(&order, db)
// type StateChangeLog struct {
// From string // from state
// To string // to state
// Note string // notes
// }
License
Released under the MIT License.
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GenerateReferenceKey ¶
GenerateReferenceKey generate reference key used for change log
Types ¶
type Event ¶
type Event struct {
Name string
// contains filtered or unexported fields
}
Event contains Event information, including transition hooks
func (*Event) To ¶
func (event *Event) To(name string) *EventTransition
To define EventTransition of go to a state
type EventTransition ¶
type EventTransition struct {
// contains filtered or unexported fields
}
EventTransition hold event's to/froms states, also including befores, afters hooks
func (*EventTransition) After ¶
func (transition *EventTransition) After(fc func(value interface{}, tx *gorm.DB) error) *EventTransition
After register after hooks
func (*EventTransition) Before ¶
func (transition *EventTransition) Before(fc func(value interface{}, tx *gorm.DB) error) *EventTransition
Before register before hooks
func (*EventTransition) From ¶
func (transition *EventTransition) From(states ...string) *EventTransition
From used to define from states
type State ¶
type State struct {
Name string
// contains filtered or unexported fields
}
State contains State information, including enter, exit hooks
type StateChangeLog ¶
type StateChangeLog struct {
gorm.Model
ReferTable string
ReferID string
From string
To string
Note string `sql:"size:1024"`
audited.AuditedModel
}
StateChangeLog a model that used to keep state change logs
func GetLastStateChange ¶
func GetLastStateChange(model interface{}, db *gorm.DB) *StateChangeLog
GetLastStateChange gets last state change
func GetStateChangeLogs ¶
func GetStateChangeLogs(model interface{}, db *gorm.DB) []StateChangeLog
GetStateChangeLogs get state change logs
type StateMachine ¶
type StateMachine struct {
// contains filtered or unexported fields
}
StateMachine a struct that hold states, events definitions
func New ¶
func New(value interface{}) *StateMachine
New initialize a new StateMachine that hold states, events definitions
func (*StateMachine) Event ¶
func (sm *StateMachine) Event(name string) *Event
Event define an event
func (*StateMachine) Initial ¶
func (sm *StateMachine) Initial(name string) *StateMachine
Initial define the initial state
type Transition ¶
type Transition struct {
State string
StateChangeLogs []StateChangeLog `sql:"-"`
}
Transition is a struct, embed it in your struct to enable state machine for the struct
func (Transition) GetState ¶
func (transition Transition) GetState() string
GetState get current state from
func (*Transition) SetState ¶
func (transition *Transition) SetState(name string)
SetState set state to Stater, just set, won't save it into database
Source Files