session provider for postgresql

This provider is based on the mysql provider: sess_mysql.go

+package session
+
+/*
+
+beego session provider for postgresql
+-------------------------------------
+
+depends on github.com/lib/pq:
+
+go install github.com/lib/pq
+
+
+needs this table in your database:
+
+CREATE TABLE session (
+session_key	char(64) NOT NULL,
+session_data	bytea,
+session_expiry	timestamp NOT NULL,
+CONSTRAINT session_key PRIMARY KEY(session_key)
+);
+
+
+will be activated with these settings in app.conf:
+
+SessionOn = true
+SessionProvider = postgresql
+SessionSavePath = "user=a password=b dbname=c sslmode=disable"
+SessionName = session
+
+*/
+
+import (
+	"database/sql"
+	"net/http"
+	"sync"
+	"time"
+	_ "github.com/lib/pq"
+)
+
+var postgresqlpder = &PostgresqlProvider{}
+
+// postgresql session store
+type PostgresqlSessionStore struct {
+	c      *sql.DB
+	sid    string
+	lock   sync.RWMutex
+	values map[interface{}]interface{}
+}
+
+// set value in postgresql session.
+// it is temp value in map.
+func (st *PostgresqlSessionStore) Set(key, value interface{}) error {
+	st.lock.Lock()
+	defer st.lock.Unlock()
+	st.values[key] = value
+	return nil
+}
+
+// get value from postgresql session
+func (st *PostgresqlSessionStore) Get(key interface{}) interface{} {
+	st.lock.RLock()
+	defer st.lock.RUnlock()
+	if v, ok := st.values[key]; ok {
+		return v
+	} else {
+		return nil
+	}
+	return nil
+}
+
+// delete value in postgresql session
+func (st *PostgresqlSessionStore) Delete(key interface{}) error {
+	st.lock.Lock()
+	defer st.lock.Unlock()
+	delete(st.values, key)
+	return nil
+}
+
+// clear all values in postgresql session
+func (st *PostgresqlSessionStore) Flush() error {
+	st.lock.Lock()
+	defer st.lock.Unlock()
+	st.values = make(map[interface{}]interface{})
+	return nil
+}
+
+// get session id of this postgresql session store
+func (st *PostgresqlSessionStore) SessionID() string {
+	return st.sid
+}
+
+// save postgresql session values to database.
+// must call this method to save values to database.
+func (st *PostgresqlSessionStore) SessionRelease(w http.ResponseWriter) {
+	defer st.c.Close()
+	b, err := encodeGob(st.values)
+	if err != nil {
+		return
+	}
+	st.c.Exec("UPDATE session set session_data=$1, session_expiry=$2 where session_key=$3",
+		b, time.Now().Format(time.RFC3339), st.sid)
+
+}
+
+// postgresql session provider
+type PostgresqlProvider struct {
+	maxlifetime int64
+	savePath    string
+}
+
+// connect to postgresql
+func (mp *PostgresqlProvider) connectInit() *sql.DB {
+	db, e := sql.Open("postgres", mp.savePath)
+	if e != nil {
+		return nil
+	}
+	return db
+}
+
+// init postgresql session.
+// savepath is the connection string of postgresql.
+func (mp *PostgresqlProvider) SessionInit(maxlifetime int64, savePath string) error {
+	mp.maxlifetime = maxlifetime
+	mp.savePath = savePath
+	return nil
+}
+
+// get postgresql session by sid
+func (mp *PostgresqlProvider) SessionRead(sid string) (SessionStore, error) {
+	c := mp.connectInit()
+	row := c.QueryRow("select session_data from session where session_key=$1", sid)
+	var sessiondata []byte
+	err := row.Scan(&sessiondata)
+	if err == sql.ErrNoRows {
+		_, err = c.Exec("insert into session(session_key,session_data,session_expiry) values($1,$2,$3)",
+			sid, "", time.Now().Format(time.RFC3339))
+
+		if err != nil {
+			return nil, err
+		}
+	} else  if err != nil {
+		return nil, err
+	}
+
+	var kv map[interface{}]interface{}
+	if len(sessiondata) == 0 {
+		kv = make(map[interface{}]interface{})
+	} else {
+		kv, err = decodeGob(sessiondata)
+		if err != nil {
+			return nil, err
+		}
+	}
+	rs := &PostgresqlSessionStore{c: c, sid: sid, values: kv}
+	return rs, nil
+}
+
+// check postgresql session exist
+func (mp *PostgresqlProvider) SessionExist(sid string) bool {
+	c := mp.connectInit()
+	defer c.Close()
+	row := c.QueryRow("select session_data from session where session_key=$1", sid)
+	var sessiondata []byte
+	err := row.Scan(&sessiondata)
+		
+	if err == sql.ErrNoRows {
+		return false
+	} else {
+		return true
+	}
+}
+
+// generate new sid for postgresql session
+func (mp *PostgresqlProvider) SessionRegenerate(oldsid, sid string) (SessionStore, error) {
+	c := mp.connectInit()
+	row := c.QueryRow("select session_data from session where session_key=$1", oldsid)
+	var sessiondata []byte
+	err := row.Scan(&sessiondata)
+	if err == sql.ErrNoRows {
+		c.Exec("insert into session(session_key,session_data,session_expiry) values($1,$2,$3)",
+		oldsid, "", time.Now().Format(time.RFC3339))
+	}
+	c.Exec("update session set session_key=$1 where session_key=$2", sid, oldsid)
+	var kv map[interface{}]interface{}
+	if len(sessiondata) == 0 {
+		kv = make(map[interface{}]interface{})
+	} else {
+		kv, err = decodeGob(sessiondata)
+		if err != nil {
+			return nil, err
+		}
+	}
+	rs := &PostgresqlSessionStore{c: c, sid: sid, values: kv}
+	return rs, nil
+}
+
+// delete postgresql session by sid
+func (mp *PostgresqlProvider) SessionDestroy(sid string) error {
+	c := mp.connectInit()
+	c.Exec("DELETE FROM session where session_key=$1", sid)
+	c.Close()
+	return nil
+}
+
+// delete expired values in postgresql session
+func (mp *PostgresqlProvider) SessionGC() {
+	c := mp.connectInit()
+	c.Exec("DELETE from session where EXTRACT(EPOCH FROM (current_timestamp - session_expiry)) > $1", mp.maxlifetime)
+	c.Close()
+	return
+}
+
+// count values in postgresql session
+func (mp *PostgresqlProvider) SessionAll() int {
+	c := mp.connectInit()
+	defer c.Close()
+	var total int
+	err := c.QueryRow("SELECT count(*) as num from session").Scan(&total)
+	if err != nil {
+		return 0
+	}
+	return total
+}
+
+func init() {
+	Register("postgresql", postgresqlpder)
+}