您好,登录后才能下订单哦!
这篇文章主要讲解了“go.cqrs中AggregateRoot的用法”,文中的讲解内容简单清晰,易于学习与理解,下面请大家跟着小编的思路慢慢深入,一起来研究和学习“go.cqrs中AggregateRoot的用法”吧!
本文主要研究一下go.cqrs的AggregateRoot
//AggregateRoot is the interface that all aggregates should implement type AggregateRoot interface { AggregateID() string OriginalVersion() int CurrentVersion() int IncrementVersion() Apply(events EventMessage, isNew bool) TrackChange(EventMessage) GetChanges() []EventMessage ClearChanges() }
AggregateRoot接口定义了AggregateID、OriginalVersion、CurrentVersion、IncrementVersion、Apply、TrackChange、GetChanges、ClearChanges方法
// AggregateBase is a type that can be embedded in an AggregateRoot // implementation to handle common aggragate behaviour // // All required methods to implement an aggregate are here, to implement the // Aggregate root interface your aggregate will need to implement the Apply // method that will contain behaviour specific to your aggregate. type AggregateBase struct { id string version int changes []EventMessage } // NewAggregateBase contructs a new AggregateBase. func NewAggregateBase(id string) *AggregateBase { return &AggregateBase{ id: id, changes: []EventMessage{}, version: -1, } } // AggregateID returns the AggregateID func (a *AggregateBase) AggregateID() string { return a.id } // OriginalVersion returns the version of the aggregate as it was when it was // instantiated or loaded from the repository. // // Importantly an aggregate with one event applied will be at version 0 // this allows the aggregates to match the version in the eventstore where // the first event will be version 0. func (a *AggregateBase) OriginalVersion() int { return a.version } // CurrentVersion returns the version of the aggregate as it was when it was // instantiated or loaded from the repository. // // Importantly an aggregate with one event applied will be at version 0 // this allows the aggregates to match the version in the eventstore where // the first event will be version 0. func (a *AggregateBase) CurrentVersion() int { return a.version + len(a.changes) } // IncrementVersion increments the aggregate version number by one. func (a *AggregateBase) IncrementVersion() { a.version++ } // TrackChange stores the EventMessage in the changes collection. // // Changes are new, unpersisted events that have been applied to the aggregate. func (a *AggregateBase) TrackChange(event EventMessage) { a.changes = append(a.changes, event) } // GetChanges returns the collection of new unpersisted events that have // been applied to the aggregate. func (a *AggregateBase) GetChanges() []EventMessage { return a.changes } //ClearChanges removes all unpersisted events from the aggregate. func (a *AggregateBase) ClearChanges() { a.changes = []EventMessage{} }
AggregateBase定义了id、version、changes属性;AggregateID方法返回id;OriginalVersion方法返回version;CurrentVersion返回version+len(a.changes);IncrementVersion递增version;TrackChange方法往changes增加event;GetChanges方法返回changes;ClearChanges会清空changes
// EventMessage is the interface that a command must implement. type EventMessage interface { // AggregateID returns the ID of the Aggregate that the event relates to AggregateID() string // GetHeaders returns the key value collection of headers for the event. // // Headers are metadata about the event that do not form part of the // actual event but are still required to be persisted alongside the event. GetHeaders() map[string]interface{} // SetHeader sets the value of the header specified by the key SetHeader(string, interface{}) // Returns the actual event which is the payload of the event message. Event() interface{} // EventType returns a string descriptor of the command name EventType() string // Version returns the version of the event Version() *int }
EventMessage接口定义了AggregateID、GetHeaders、SetHeader、Event、EventType、Version方法
// EventDescriptor is an implementation of the event message interface. type EventDescriptor struct { id string event interface{} headers map[string]interface{} version *int } // NewEventMessage returns a new event descriptor func NewEventMessage(aggregateID string, event interface{}, version *int) *EventDescriptor { return &EventDescriptor{ id: aggregateID, event: event, headers: make(map[string]interface{}), version: version, } } // EventType returns the name of the event type as a string. func (c *EventDescriptor) EventType() string { return typeOf(c.event) } // AggregateID returns the ID of the Aggregate that the event relates to. func (c *EventDescriptor) AggregateID() string { return c.id } // GetHeaders returns the headers for the event. func (c *EventDescriptor) GetHeaders() map[string]interface{} { return c.headers } // SetHeader sets the value of the header specified by the key func (c *EventDescriptor) SetHeader(key string, value interface{}) { c.headers[key] = value } // Event the event payload of the event message func (c *EventDescriptor) Event() interface{} { return c.event } // Version returns the version of the event func (c *EventDescriptor) Version() *int { return c.version }
EventDescriptor定义了id、event、headers、version属性;其EventType返回typeOf(c.event);AggregateID返回id;GetHeaders返回headers;SetHeader会设置header;Event方法返回event;Version返回version
go.cqrs的AggregateRoot接口定义了AggregateID、OriginalVersion、CurrentVersion、IncrementVersion、Apply、TrackChange、GetChanges、ClearChanges方法。
感谢各位的阅读,以上就是“go.cqrs中AggregateRoot的用法”的内容了,经过本文的学习后,相信大家对go.cqrs中AggregateRoot的用法这一问题有了更深刻的体会,具体使用情况还需要大家实践验证。这里是亿速云,小编将为大家推送更多相关知识点的文章,欢迎关注!
免责声明:本站发布的内容(图片、视频和文字)以原创、转载和分享为主,文章观点不代表本网站立场,如果涉及侵权请联系站长邮箱:is@yisu.com进行举报,并提供相关证据,一经查实,将立刻删除涉嫌侵权内容。