postgresworker

README

Example

This is example for create Postgres Event Listener (CDC), inspired by Hasura Event Triggers

Create delivery handler

package workerhandler

import (
	"context"
	"encoding/json"
	
	"example.service/internal/modules/examplemodule/delivery/workerhandler"

	"github.com/golangid/candi/candishared"
	"github.com/golangid/candi/codebase/factory/types"
	"github.com/golangid/candi/tracer"
)

// PostgresListenerHandler struct
type PostgresListenerHandler struct {
	uc        usecase.Usecase
	validator interfaces.Validator
}

// NewPostgresListenerHandler constructor
func NewPostgresListenerHandler(uc usecase.Usecase, validator interfaces.Validator) *PostgresListenerHandler {
	return &PostgresListenerHandler{
		uc:        uc,
		validator: validator,
	}
}

// MountHandlers mount handler group
func (h *PostgresListenerHandler) MountHandlers(group *types.WorkerHandlerGroup) {
	group.Add("table-names", h.handleDataChange) // listen change data capture on table "table-names"
}

func (h *PostgresListenerHandler) handleDataChange(eventContext *candishared.EventContext) error {
	trace := tracer.StartTrace(eventContext.Context(), "DeliveryPostgresListener:HandleDataChange")
	defer trace.Finish()

	fmt.Printf("data change on table 'table-names' detected: %s\n", eventContext.Message())
	// call usecase
	return nil
}

Register in module

package examplemodule

import (
	"example.service/internal/modules/examplemodule/delivery/workerhandler"

	"github.com/golangid/candi/codebase/factory/dependency"
	"github.com/golangid/candi/codebase/factory/types"
	"github.com/golangid/candi/codebase/interfaces"
)

type Module struct {
	// ...another delivery handler
	workerHandlers map[types.Worker]interfaces.WorkerHandler
}

func NewModules(deps dependency.Dependency) *Module {
	return &Module{
		workerHandlers: map[types.Worker]interfaces.WorkerHandler{
			// ...another worker handler
			// ...
			types.PostgresListener: workerhandler.NewPostgresListenerHandler(usecaseUOW.User(), deps.GetValidator()),
		},
	}
}

// ...another method

Message in JSON Payload

{
	"event_id": "<md5-hash-unique-event-id>",
	"table": "<table-name>",
	"action": "<operation-name>", // INSERT, UPDATE, or DELETE
	"data": {
		"old": <old-column-values-object>,
		"new": <new-column-values-object>
	}
}

Documentation

Index

• Constants
• func CreateHandlerRoute(sourceName, tableName string) string
• func NewWorker(service factory.ServiceFactory, opts ...OptionFunc) factory.AppServerFactory
• func ParseHandlerRoute(str string) (sourceName, tableName string)
• type EventPayload
  • func (e EventPayload) GetID() string
• type EventPayloadData
• type OptionFunc
  • func AddPostgresDSN(sourceName, dsn string) OptionFunc
  • func SetDebugMode(debugMode bool) OptionFunc
  • func SetLocker(locker interfaces.Locker) OptionFunc
  • func SetMaxGoroutines(maxGoroutines int) OptionFunc
  • func SetPostgresDSN(dsn string) OptionFunc
• type PostgresHandlerRouteKey
  • func (p PostgresHandlerRouteKey) String() string
• type PostgresSource

Constants

const (
	// ActionInsert const
	ActionInsert = "INSERT"
	// ActionUpdate const
	ActionUpdate = "UPDATE"
	// ActionDelete const
	ActionDelete = "DELETE"
)

Functions

func CreateHandlerRoute

func CreateHandlerRoute(sourceName, tableName string) string

CreateHandlerRoute creating key pattern for handler

func NewWorker

func NewWorker(service factory.ServiceFactory, opts ...OptionFunc) factory.AppServerFactory

NewWorker create new postgres event listener

func ParseHandlerRoute

func ParseHandlerRoute(str string) (sourceName, tableName string)

ParseHandlerRoute helper

Types

type EventPayload

type EventPayload struct {
	EventID string           `json:"event_id"`
	Table   string           `json:"table"`
	Action  string           `json:"action"`
	Data    EventPayloadData `json:"data"`
}

EventPayload event model

func (EventPayload) GetID

func (e EventPayload) GetID() string

GetID get id if old/new data is empty, cause from long payload limitation

type EventPayloadData

type EventPayloadData struct {
	IsTooLongPayload bool        `json:"is_too_long_payload,omitempty"`
	OldID            string      `json:"old_id"`
	NewID            string      `json:"new_id"`
	Old              interface{} `json:"old"`
	New              interface{} `json:"new"`
}

EventPayloadData event data

type OptionFunc

type OptionFunc func(*option)

OptionFunc type

func AddPostgresDSN

func AddPostgresDSN(sourceName, dsn string) OptionFunc

AddPostgresDSN option func for add multple postgres source to be listen

func SetDebugMode

func SetDebugMode(debugMode bool) OptionFunc

SetDebugMode option func

func SetLocker

func SetLocker(locker interfaces.Locker) OptionFunc

SetLocker option func

func SetMaxGoroutines

func SetMaxGoroutines(maxGoroutines int) OptionFunc

SetMaxGoroutines option func

func SetPostgresDSN

func SetPostgresDSN(dsn string) OptionFunc

SetPostgresDSN option func

type PostgresHandlerRouteKey

type PostgresHandlerRouteKey struct {
	SourceName string `json:"sourceName"`
	TableName  string `json:"tableName"`
}

PostgresHandlerRouteKey key model

func (PostgresHandlerRouteKey) String

func (p PostgresHandlerRouteKey) String() string

String implement stringer

type PostgresSource

type PostgresSource struct {
	// contains filtered or unexported fields
}

PostgresSource model