WASAPhoto/service/database/database.go

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/*
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()
}