Made Version function public

database.go

@@ -19,11 +19,11 @@ func newDatabase(host string, port int, dbName, user, pass string) (dbase Databa
 
 func (dbase Database) sqlConnString() string {// {{{
 	return fmt.Sprintf(
-		"postgresql://%s:%s@%s:%d/%s?sslmode=disable",
-		dbase.Username,
-		dbase.Password,
+		"host=%s port=%d user=%s password=%s dbname=%s sslmode=disable",
 		dbase.Host,
 		dbase.Port,
+		dbase.Username,
+		dbase.Password,
 		dbase.DbName,
 	)
 }// }}}

schema.go

@@ -1,3 +1,22 @@
+/*
+Package dbschema is used to keep the SQL schema up to date.
+
+	func sqlProvider(dbName string, version int) (sql []byte, found bool) {
+		// read an SQL file and return the contents
+		return
+	}
+
+	upgrader := dbschema.NewUpgrader()
+	upgrader.SetSqlCallback(sqlProvider)
+
+	if err = upgrader.AddDatabase("127.0.0.1", 5432, "foo", "postgres", "password"); err != nil {
+		panic(err)
+	}
+
+	if err = upgrader.Run(); err != nil {
+		panic(err)
+	}
+*/
 package dbschema
 
 import (
@@ -8,9 +27,10 @@ import (
 	"database/sql"
 )
 
+// An upgrader verifies the schema for one or more databases and upgrades them if possible.
 type Upgrader struct {
-	schemaDb Database
-	databases map[string]Database
+	schema      string
+	databases   map[string]Database
 	logCallback func(string, string)
 	sqlCallback func(string, int) ([]byte, bool)
 }
@@ -22,50 +42,8 @@ type Database struct {
 	Username string
 	Password string
 
-	db *sql.DB
-	schemaDb *Database
+	db       *sql.DB
+	upgrader *Upgrader
 }
 
-/*
-func dbUpdate() (err error) {// {{{
-	var rows *sqlx.Rows
-	var schemaStr string
-	var schema int
-	rows, err = db.Queryx(`SELECT value FROM _internal.db WHERE "key"='schema'`)
-	if err != nil { return }
-	defer rows.Close()
-
-	if !rows.Next() {
-		return errors.New("Table _interval.db missing schema row")
-	}
-
-	if err = rows.Scan(&schemaStr); err != nil {
-		return
-	}
-
-	// Run updates
-	schema, err = strconv.Atoi(schemaStr)
-	if err != nil {
-		return err
-	}
-	for i := (schema+1); i <= DB_SCHEMA; i++ {
-		log.Printf("\x1b[32mNotes\x1b[0m Upgrading SQL schema to revision %d...", i)
-		sql, _ := embedded.ReadFile(
-			fmt.Sprintf("sql/%04d.sql", i),
-		)
-		_, err = db.Exec(string(sql))
-		if err != nil {
-			return
-		}
-		_, err = db.Exec(`UPDATE _internal.db SET "value"=$1 WHERE "key"='schema'`, i)
-		if err != nil {
-			return
-		}
-		log.Printf("\x1b[32mNotes\x1b[0m OK: %d", i)
-	}
-
-	return
-}// }}}
-*/
-
 // vim: foldmethod=marker

upgrader.go

@@ -1,6 +1,9 @@
 package dbschema
 
 import (
+	// External
+	"github.com/lib/pq"
+
 	// Standard
 	"database/sql"
 	"fmt"
@@ -9,33 +12,74 @@ import (
 func defaultCallback(topic, msg string) {// {{{
 	fmt.Printf("[%s] %s\n", topic, msg)
 }// }}}
-func NewUpgrader(host string, port int, dbName, user, pass string) (upgrader Upgrader, err error) {// {{{
+
+// NewUpgrader creates an upgrader with an empty list of databases.
+func NewUpgrader(schema ...string) (upgrader Upgrader) {// {{{
+	// Using a variadic function for backward compatibility.
+	if len(schema) > 0 {
+		upgrader.schema = schema[0]
+	} else {
+		upgrader.schema = "_db"
+	}
+
 	upgrader.logCallback = defaultCallback
 	upgrader.databases = map[string]Database{}
-	upgrader.schemaDb, err = newDatabase(
-		host,
-		port,
-		dbName,
-		user,
-		pass,
-	)
-	err = upgrader.verifySchemaTable()
 	return
 }// }}}
 
+// SetLogCallback allows to set a callback for custom logging.
 func (upgrader *Upgrader) SetLogCallback(callback func(string, string)) {// {{{
 	upgrader.logCallback = callback
 }// }}}
+// SetSqlCallback is required for providing the SQL schema updates.
 func (upgrader *Upgrader) SetSqlCallback(callback func(string, int) ([]byte, bool)) {// {{{
 	upgrader.sqlCallback = callback
 }// }}}
-func (upgrader Upgrader) verifySchemaTable() (err error) {// {{{
+// Version returns the current dbschema version for the given database name.
+func (upgrader *Upgrader) Version(dbName string) (version int, err error) {// {{{
+	dbase, found := upgrader.databases[dbName]
+	if !found {
+		err = fmt.Errorf("Database %s not previously added to the upgrader", dbName)
+		return
+	}
+
+	version, err = dbase.Version()
+	return
+}// }}}
+
+func (dbase Database) createSchemaTable() (err error) {// {{{
+	dbase.upgrader.logCallback("create", fmt.Sprintf("%s, %s.schema", dbase.DbName, dbase.upgrader.schema))
+	_, err = dbase.db.Exec(`CREATE SCHEMA "`+dbase.upgrader.schema+`"`)
+
+	// Error code 42P06 "duplicate_schema" is an OK error,
+	// table can still be missing and created.
+	pqErr, _ := err.(*pq.Error)
+	if pqErr != nil && pqErr.Code != "42P06" {
+		return
+	}
+
+	_, err = dbase.db.Exec(`
+		CREATE TABLE "`+dbase.upgrader.schema+`"."schema" (
+			version  int4      NOT NULL,
+			updated  timestamp NOT NULL DEFAULT NOW(),
+
+			CONSTRAINT schema_pk PRIMARY KEY (version)
+		)`,
+	)
+	return
+}// }}}
+func (dbase Database) appendSchemaVersion(version int) (err error) {// {{{
+	_, err = dbase.db.Exec(`INSERT INTO `+dbase.upgrader.schema+`.schema(version) VALUES($1)`, version)
+	return
+}// }}}
+
+func (dbase Database) verifySchemaTable() (err error) {// {{{
 	var rows *sql.Rows
-	if rows, err = upgrader.schemaDb.db.Query(
+	if rows, err = dbase.db.Query(
 		`SELECT EXISTS (
 			SELECT FROM pg_catalog.pg_class c
 			JOIN   pg_catalog.pg_namespace n ON n.oid = c.relnamespace
-			WHERE  n.nspname = '_db'
+			WHERE  n.nspname = '`+dbase.upgrader.schema+`'
 			AND    c.relname = 'schema'
 		)`,
 	); err != nil {
@@ -48,48 +92,29 @@ func (upgrader Upgrader) verifySchemaTable() (err error) {// {{{
 		return
 	}
 
-	if !exists {
-		upgrader.logCallback("create", "_db.schema")
-		upgrader.schemaDb.db.Exec(`CREATE SCHEMA "_db"`)
-
-		if _, err = upgrader.schemaDb.db.Exec(`
-			CREATE TABLE "_db"."schema" (
-				database varchar   NOT NULL,
-				version  int4      NOT NULL,
-				updated  timestamp NOT NULL DEFAULT NOW(),
-
-				CONSTRAINT schema_pk PRIMARY KEY (database)
-			);
-			`,
-		); err != nil {
-			return
-		}
-	}
-	return
-}// }}}
-func (upgrader Upgrader) verifySchemaEntry(dbase Database) (err error) {// {{{
-	var rows *sql.Rows
-	rows, err = upgrader.schemaDb.db.Query(`SELECT version FROM _db.schema WHERE database=$1`, dbase.DbName)
-	if err != nil {
+	if exists {
 		return
 	}
-	defer rows.Close()
+	err = dbase.createSchemaTable()
+	return
+}// }}}
+func (dbase Database) verifySchemaEntry() (err error) {// {{{
+	var version int
+	var row *sql.Row
+	row = dbase.db.QueryRow(`SELECT version FROM `+dbase.upgrader.schema+`.schema LIMIT 1`)
 
-	if !rows.Next() {
-		upgrader.logCallback("initiate version", dbase.DbName)
-		_, err = upgrader.schemaDb.db.Exec(`INSERT INTO _db.schema(database, version) VALUES($1, 0)`, dbase.DbName)
-		if err != nil {
-			return
-		}
+	err = row.Scan(&version)
+	if err == sql.ErrNoRows {
+		dbase.upgrader.logCallback("initiate version", dbase.DbName)
+		err = dbase.appendSchemaVersion(0)
 	}
 
 	return
 }// }}}
-func (upgrader Upgrader) version(dbName string) (version int, err error) {// {{{
+func (dbase Database) Version() (version int, err error) {// {{{
 	var rows *sql.Rows
-	rows, err = upgrader.schemaDb.db.Query(
-		`SELECT version FROM _db.schema WHERE database=$1`,
-		dbName,
+	rows, err = dbase.db.Query(
+		`SELECT version FROM `+dbase.upgrader.schema+`.schema ORDER BY version DESC LIMIT 1`,
 	)
 	if err != nil {
 		return
@@ -99,31 +124,37 @@ func (upgrader Upgrader) version(dbName string) (version int, err error) {// {{{
 	if rows.Next() {
 		err = rows.Scan(&version)
 	} else {
-		err = fmt.Errorf(`Database "%s" is missing an entry in _db.schema`, dbName)
+		err = fmt.Errorf(`Database "%s" is missing an entry in `+dbase.upgrader.schema+`.schema`, dbase.DbName)
 	}
 	return
 }// }}}
 
-func (upgrader Upgrader) AddDatabase(host string, port int, dbName, user, pass string) (err error) {// {{{
-	var db Database
+// AddDatabase sets a database up for the Run() function with verifying/creating the _db.schema table.
+func (upgrader Upgrader) AddDatabase(host string, port int, dbName, user, pass string) (db Database, err error) {// {{{
 	if db, err = newDatabase(host, port, dbName, user, pass); err != nil {
 		return
 	}
+	db.upgrader = &upgrader
 	
 	upgrader.databases[dbName] = db
 
-	err = upgrader.verifySchemaEntry(db)
+	if err = db.verifySchemaTable(); err != nil {
+		return
+	}
+
+	err = db.verifySchemaEntry()
 	return
 }// }}}
+// Run executes the actual schema updates until there are no more available.
 func (upgrader Upgrader) Run() (err error) {// {{{
 	var version int
 
-	for dbName, db := range upgrader.databases {
-		version, err = upgrader.version(dbName)
+	for dbName, dbase := range upgrader.databases {
+		version, err = dbase.Version()
 		if err != nil {
 			return
 		}
-		upgrader.logCallback("version", fmt.Sprintf("%s: %d", dbName, version))
+		upgrader.logCallback("version", fmt.Sprintf("%s.%s: %d", dbName, upgrader.schema, version))
 
 		for {
 			version++
@@ -132,18 +163,11 @@ func (upgrader Upgrader) Run() (err error) {// {{{
 				break
 			}
 
-			upgrader.logCallback("exec", fmt.Sprintf("%s: %d", dbName, version))
-			if _, err = db.db.Exec(string(sql)); err != nil {
+			upgrader.logCallback("exec", fmt.Sprintf("%s.%s: %d", dbName, upgrader.schema, version))
+			if _, err = dbase.db.Exec(string(sql)); err != nil {
 				return
 			}
-			_, err = upgrader.schemaDb.db.Exec(`
-				UPDATE _db.schema
-				SET
-					version=$1,
-					updated=NOW()
-				WHERE database=$2
-			`, version, dbName)
-			if err != nil {
+			if err = dbase.appendSchemaVersion(version); err != nil {
 				return
 			}
 		}