Implements postgres store

[pablogore]

Do you plan to add new stores to the list, like Postgres or MySQL,?
Could you add some guidelines to help me, I could add Postgres store implementation, really you did wonderful work.
Thanks

[bounoable]

Hey @pablogore, thank you first of all :) I haven't had the time for it yet but MySQL/Postgres implementation is definitely on the todo list. If you'd like to do the implementation, you would need to create the backend/postgres directory and add the store_test.go file with the following contents:

// backend/postgres/store_test.go
//go:build postgres
package postgres_test

import (
	"testing"

	"github.com/modernice/goes/backend/postgres"
	"github.com/modernice/goes/backend/testing/eventstoretest"
	"github.com/modernice/goes/codec"
	"github.com/modernice/goes/event"
)

var _ event.Store = postgres.NewEventStore()

func TestEventStore(t *testing.T) {
	eventstoretest.Run(t, "postgres", func(codec.Encoding) event.Store {
		return postgres.NewEventStore()
	})
}

Then implement the event store in backend/postgres/store.go.

package postgres

type EventStore struct { ... }

type EventStoreOption func(*EventStore)

func NewEventStore(opts ...EventStoreOption) *EventStore { ... }

func (*EventStore) Insert(context.Context, ...event.Event) error { ... }

func (*EventStore) Find(context.Context, uuid.UUID) (event.Event, error) { ... }

func (*EventStore) Query(context.Context, event.Query) (<-chan event.Event, <-chan error, error) { ... }

func (*EventStore) Delete(context.Context, ...event.Event) error { ... }

The store should connect to 127.0.0.1:5432 and use the events database by default. An option should be provided to override the default connection string and database:

package example

func example() {
  store := postgres.NewEventStore(postgres.Connection("postgres://username:password@localhost:5432/database_name"))
}

I would recommend using the pgx package to implement the store.

For guidance you can look at the in-memory and MongoDB implementations of the event store.

If you're familiar with Docker, then roughly this docker-compose configuration should be created as .docker/postgres-test.yml:

version: '3.8'
services:
  postgresstore:
    image: postgres

  test:
    depends_on:
      - postgresstore
    build:
      context: ..
      dockerfile: .docker/tag-test.Dockerfile
      args:
        TAGS: postgres

And this script should be added to the Makefile:

.PHONY: postgres-test
postgres-test:
	docker-compose -f .docker/postgres-test.yml up --build --abort-on-container-exit --remove-orphans; \
	docker-compose -f .docker/postgres-test.yml down --remove-orphans

If you have any questions or issues, feel free to ask :)