persistenceServices

persistenceServices

Sharing out of good will and generally unsupported

... I'm still debating its usefulness so please raise an issue if you wish to contribute and we'll discuss

Thanks, Adrian

Introduction

This module implements a persistence layer, with optional CQRS

• Google Firestore
• Google Pubsub
• [Future] Azure Cosmodb
• [Future] Azure Event Hub
• etc

Installation

go get github.com/adeturner/persistenceServices
go test

Implementation

Code

Define a docType, must implement documentType:

type documentType interface {
	String() string
	Topic() string
}

type DocType int

// example doc types
const (
	DOCUMENT_TYPE_USERS DocType = iota
	DOCUMENT_TYPE_ORDERS
	DOCUMENT_TYPE_STOCK
)

// Generic name for the Document, used as the Firestore Collection name
func (d DocType) String() string {
	return [...]string{
		"Users",
		"Orders",
		"Stock",
	}[d]
}

// Returns the eventing topic name; topic must be precreated
func (d DocType) Topic() string {
	return [...]string{
		"usersTopic",
		"ordersTopic",
		"stockTopic",
	}[d]
}

Instantiate the persistenceLayer

var persistenceLayer *persistenceServices.PersistenceLayer
ver err error
d := DOCUMENT_TYPE_USERS

// deprecated
p, err := GetPersistenceLayer(docType)

// new
p, err = GetLayer()
p.SetDocType(docType)

Available functions

func GetPersistenceLayer(docType documentType) (*PersistenceLayer, error) {
func (p *PersistenceLayer) AddDocument(key string, values interface{}) error {
func (p *PersistenceLayer) UpdateDocument(key string, values interface{}) error {
func (p *PersistenceLayer) DeleteDocument(key string, values interface{}) error {
func (p *PersistenceLayer) FindById(key string, values interface{}) (interface{}, error) {
func (p *PersistenceLayer) FindByTags(tags []string, strlimit string, value interface{}, valuesArray interface{}) (interface{}, error) {

Example usage

UUID := uuid.New().String()
u := User{Id: UUID, Name: "SomeName", Tag: "SomeTags"}
err := p.AddDocument(UUID, u)

Setup

Environment variables control the data layer access

export CLOUDEVENT_DOMAIN=mydomain.com // Cloud events will have source {CLOUDEVENT_DOMAIN}/{docType.String}
export DEBUG=false            // if true, debug output on
export USE_FIRESTORE=true     // if true reads will come from here; writes will also go here if USE_CQRS=false
export USE_PUBSUB=true        // if true enables a pubsub connection
export USE_CQRS=false         // if true writes are sent to pubsub
export GCP_PROJECT=myproject  // project for GCP connections
export GOOGLE_APPLICATION_CREDENTIALS=~/secrets/persistenceServices.json  // if testing outside of GCP

Tests

./test/localtests.sh