initial commit

service/database/database.go

@@ -0,0 +1,76 @@
+/*
+Package database is the middleware between the app database and the code. All data (de)serialization (save/load) from a
+persistent database are handled here. Database specific logic should never escape this package.
+
+To use this package you need to apply migrations to the database if needed/wanted, connect to it (using the database
+data source name from config), and then initialize an instance of AppDatabase from the DB connection.
+
+For example, this code adds a parameter in `webapi` executable for the database data source name (add it to the
+main.WebAPIConfiguration structure):
+
+	DB struct {
+		Filename string `conf:""`
+	}
+
+This is an example on how to migrate the DB and connect to it:
+
+	// Start Database
+	logger.Println("initializing database support")
+	db, err := sql.Open("sqlite3", "./foo.db")
+	if err != nil {
+		logger.WithError(err).Error("error opening SQLite DB")
+		return fmt.Errorf("opening SQLite: %w", err)
+	}
+	defer func() {
+		logger.Debug("database stopping")
+		_ = db.Close()
+	}()
+
+Then you can initialize the AppDatabase and pass it to the api package.
+*/
+package database
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+)
+
+// AppDatabase is the high level interface for the DB
+type AppDatabase interface {
+	GetName() (string, error)
+	SetName(name string) error
+
+	Ping() error
+}
+
+type appdbimpl struct {
+	c *sql.DB
+}
+
+// New returns a new instance of AppDatabase based on the SQLite connection `db`.
+// `db` is required - an error will be returned if `db` is `nil`.
+func New(db *sql.DB) (AppDatabase, error) {
+	if db == nil {
+		return nil, errors.New("database is required when building a AppDatabase")
+	}
+
+	// Check if table exists. If not, the database is empty, and we need to create the structure
+	var tableName string
+	err := db.QueryRow(`SELECT name FROM sqlite_master WHERE type='table' AND name='example_table';`).Scan(&tableName)
+	if errors.Is(err, sql.ErrNoRows) {
+		sqlStmt := `CREATE TABLE example_table (id INTEGER NOT NULL PRIMARY KEY, name TEXT);`
+		_, err = db.Exec(sqlStmt)
+		if err != nil {
+			return nil, fmt.Errorf("error creating database structure: %w", err)
+		}
+	}
+
+	return &appdbimpl{
+		c: db,
+	}, nil
+}
+
+func (db *appdbimpl) Ping() error {
+	return db.c.Ping()
+}

service/database/get-name.go

@@ -0,0 +1,8 @@
+package database
+
+// GetName is an example that shows you how to query data
+func (db *appdbimpl) GetName() (string, error) {
+	var name string
+	err := db.c.QueryRow("SELECT name FROM example_table WHERE id=1").Scan(&name)
+	return name, err
+}

service/database/set-name.go

@@ -0,0 +1,7 @@
+package database
+
+// SetName is an example that shows you how to execute insert/update
+func (db *appdbimpl) SetName(name string) error {
+	_, err := db.c.Exec("INSERT INTO example_table (id, name) VALUES (1, ?)", name)
+	return err
+}