Fix tagged posts SQLite query

SQLite doesn't have an `RLIKE` function, so the query for hashtagged
posts was failing before. This adds a `regexp` function to SQLite and
correctly retrieves all posts on a blog with the requested hashtag.

This closes #55

app.go

@@ -483,7 +483,7 @@ func connectToDatabase(app *app) {
 			log.Error("SQLite database filename value in config.ini is empty.")
 			os.Exit(1)
 		}
-		db, err = sql.Open("sqlite3", app.cfg.Database.FileName+"?parseTime=true&cached=shared")
+		db, err = sql.Open("sqlite3_with_regex", app.cfg.Database.FileName+"?parseTime=true&cached=shared")
 		db.SetMaxOpenConns(1)
 	} else {
 		log.Error("Invalid database type '%s'. Only 'mysql' and 'sqlite3' are supported right now.", app.cfg.Database.Type)

database-sqlite.go

@@ -13,13 +13,24 @@
 package writefreely
 
 import (
+	"database/sql"
 	"github.com/go-sql-driver/mysql"
 	"github.com/mattn/go-sqlite3"
 	"github.com/writeas/web-core/log"
+	"regexp"
 )
 
 func init() {
 	SQLiteEnabled = true
+
+	regex := func(re, s string) (bool, error) {
+		return regexp.MatchString(re, s)
+	}
+	sql.Register("sqlite3_with_regex", &sqlite3.SQLiteDriver{
+		ConnectHook: func(conn *sqlite3.SQLiteConn) error {
+			return conn.RegisterFunc("regexp", regex, true)
+		},
+	})
 }
 
 func (db *datastore) isDuplicateKeyErr(err error) bool {

database.go

@@ -1139,7 +1139,14 @@ func (db *datastore) GetPostsTagged(c *Collection, tag string, page int, include
 	if !includeFuture {
 		timeCondition = "AND created <= " + db.now()
 	}
-	rows, err := db.Query("SELECT "+postCols+" FROM posts WHERE collection_id = ? AND LOWER(content) RLIKE ? "+timeCondition+" ORDER BY created "+order+limitStr, collID, "#"+strings.ToLower(tag)+"[[:>:]]")
+
+	var rows *sql.Rows
+	var err error
+	if db.driverName == driverSQLite {
+		rows, err = db.Query("SELECT "+postCols+" FROM posts WHERE collection_id = ? AND LOWER(content) regexp ? "+timeCondition+" ORDER BY created "+order+limitStr, collID, `.*#`+strings.ToLower(tag)+`\b.*`)
+	} else {
+		rows, err = db.Query("SELECT "+postCols+" FROM posts WHERE collection_id = ? AND LOWER(content) RLIKE ? "+timeCondition+" ORDER BY created "+order+limitStr, collID, "#"+strings.ToLower(tag)+"[[:>:]]")
+	}
 	if err != nil {
 		log.Error("Failed selecting from posts: %v", err)
 		return nil, impart.HTTPError{http.StatusInternalServerError, "Couldn't retrieve collection posts."}