postgresworker

README

Example

This is example for create Postgres Event Listener, 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/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 data change on table "table-names"
}

func (h *PostgresListenerHandler) handleDataChange(ctx context.Context, message []byte) error {
	trace := tracer.StartTrace(ctx, "DeliveryPostgresListener:HandleDataChange")
	defer trace.Finish()
	ctx = trace.Context()

	fmt.Printf("data change on table 'table-names' detected: %s\n", 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

JSON Payload

Received on messages ([]byte data type) in handler param.

{
  "table": "<table-name>",
  "action": "<operation-name>", // INSERT, UPDATE, or DELETE
  "data": {
    "old": <old-column-values-object>,
    "new": <new-column-values-object>
  }
}

Documentation

Index

• func NewWorker(service factory.ServiceFactory, opts ...OptionFunc) factory.AppServerFactory
• type EventPayload
• type OptionFunc
  • func SetConsul(consul *candiutils.Consul) OptionFunc
  • func SetDebugMode(debugMode bool) OptionFunc
  • func SetMaxGoroutines(maxGoroutines int) OptionFunc
  • func SetPostgresDSN(dsn string) OptionFunc

Functions

func NewWorker

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

NewWorker create new postgres event listener

Types

type EventPayload

type EventPayload struct {
	Table  string `json:"table"`
	Action string `json:"action"`
}

EventPayload event model

type OptionFunc

type OptionFunc func(*option)

OptionFunc type

func SetConsul

func SetConsul(consul *candiutils.Consul) OptionFunc

SetConsul option func

func SetDebugMode

func SetDebugMode(debugMode bool) OptionFunc

SetDebugMode option func

func SetMaxGoroutines

func SetMaxGoroutines(maxGoroutines int) OptionFunc

SetMaxGoroutines option func

func SetPostgresDSN

func SetPostgresDSN(dsn string) OptionFunc

SetPostgresDSN option func