init

dao/postgres.go

@@ -0,0 +1,47 @@
+package dao
+
+import (
+	"database/sql"
+	"fmt"
+	"github.com/kratisto/mam-contract/configuration"
+
+	_ "github.com/lib/pq" // Required to use the driver with database/sql
+)
+
+// Database is the interface for DB access
+type Database interface {
+	Ping() error
+}
+
+// DatabasePostgreSQL is the implementation of the Database interface for PostgreSQL
+type DatabasePostgreSQL struct {
+	session *sql.DB
+	schema  string
+}
+
+// NewDatabasePostgreSQL returns an instance of the database
+func NewDatabasePostgreSQL(config *configuration.Config) Database {
+	var (
+		dbSession *sql.DB
+		err       error
+	)
+
+	connectionURI := fmt.Sprintf("postgresql://%s:%s@%s/%s?sslmode=disable", config.PostgresUser, config.PostgresPwd, config.PostgresHost, config.PostgresDBName)
+	dbSession, err = sql.Open("postgres", connectionURI)
+	if err != nil {
+		return nil
+	}
+
+	err = dbSession.Ping()
+	if err != nil {
+		return nil
+	}
+	return &DatabasePostgreSQL{session: dbSession, schema: config.PostgresDBSchema}
+}
+
+// Ping doesn't use db.Ping because it doesn't Ping after the first time
+// https://stackoverflow.com/a/41619206/3853913
+func (db *DatabasePostgreSQL) Ping() error {
+	_, err := db.session.Query("SELECT WHERE 1=0")
+	return err
+}