Introduce Stmt#Select method.

README

@@ -39,7 +39,7 @@ Conn#GetAutocommit
 Conn#EnableLoadExtension/LoadExtension
 Conn#IntegrityCheck
 
-Stmt#ExecInsert/ExecUpdate
+Stmt#Insert/ExecDml/Select
 Stmt#BindParameterCount/BindParameterIndex(name)/BindParameterName(index)
 Stmt#ClearBindings
 Stmt#ColumnCount/ColumnNames/ColumnIndex(name)/ColumnName(index)/ColumnType(index)

function.go

@@ -347,7 +347,7 @@ func goXAuxDataDestroy(ad unsafe.Pointer) {
 	if c != nil {
 		delete(contexts, c.sc)
 	}
-//	fmt.Printf("Contexts: %v\n", contexts)
+	//	fmt.Printf("Contexts: %v\n", contexts)
 }
 
 //export goXFunc
@@ -404,7 +404,7 @@ func goXFinal(scp, udfp unsafe.Pointer) {
 			udf.final(c)
 		}
 	}
-//	fmt.Printf("Contexts: %v\n", contexts)
+	//	fmt.Printf("Contexts: %v\n", contexts)
 }
 
 //export goXDestroy

meta.go

@@ -26,17 +26,15 @@ func (c *Conn) Databases() (map[string]string, error) {
 	defer s.Finalize()
 	var databases map[string]string = make(map[string]string)
 	var name, file string
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
-		err = s.Scan(nil, &name, &file)
-		if err != nil {
-			return nil, err
+	err = s.Select(func(s *Stmt) (err error) {
+		if err = s.Scan(nil, &name, &file); err != nil {
+			return
 		}
 		databases[name] = file
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return databases, nil
 }
@@ -50,18 +48,13 @@ func (c *Conn) Tables() ([]string, error) {
 	}
 	defer s.Finalize()
 	var tables []string = make([]string, 0, 20)
-	var name string
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
-		err = s.Scan(&name)
-		if err != nil {
-			return nil, err
-		}
+	err = s.Select(func(s *Stmt) (err error) {
+		name, _ := s.ScanText(0)
 		tables = append(tables, name)
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return tables, nil
 }
@@ -86,18 +79,16 @@ func (c *Conn) Columns(table string) ([]Column, error) {
 	}
 	defer s.Finalize()
 	var columns []Column = make([]Column, 0, 20)
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
+	err = s.Select(func(s *Stmt) (err error) {
 		c := Column{}
-		err = s.Scan(&c.Cid, &c.Name, &c.DataType, &c.NotNull, &c.DfltValue, &c.Pk)
-		if err != nil {
-			return nil, err
+		if err = s.Scan(&c.Cid, &c.Name, &c.DataType, &c.NotNull, &c.DfltValue, &c.Pk); err != nil {
+			return
 		}
 		columns = append(columns, c)
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return columns, nil
 }
@@ -120,15 +111,9 @@ func (c *Conn) ForeignKeys(table string) (map[int]*ForeignKey, error) {
 	var fks = make(map[int]*ForeignKey)
 	var id, seq int
 	var ref, from, to string
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
-		err = s.NamedScan("id", &id, "seq", &seq, "table", &ref, "from", &from, "to", &to)
-		if err != nil {
-			return nil, err
+	err = s.Select(func(s *Stmt) (err error) {
+		if err = s.NamedScan("id", &id, "seq", &seq, "table", &ref, "from", &from, "to", &to); err != nil {
+			return
 		}
 		fk, ex := fks[id]
 		if !ex {
@@ -138,6 +123,10 @@ func (c *Conn) ForeignKeys(table string) (map[int]*ForeignKey, error) {
 		// TODO Ensure columns are appended in the correct order...
 		fk.From = append(fk.From, from)
 		fk.To = append(fk.To, to)
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return fks, nil
 }
@@ -157,18 +146,16 @@ func (c *Conn) Indexes(table string) ([]Index, error) {
 	}
 	defer s.Finalize()
 	var indexes []Index = make([]Index, 0, 5)
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
+	err = s.Select(func(s *Stmt) (err error) {
 		i := Index{}
-		err = s.Scan(nil, &i.Name, &i.Unique)
-		if err != nil {
-			return nil, err
+		if err = s.Scan(nil, &i.Name, &i.Unique); err != nil {
+			return
 		}
 		indexes = append(indexes, i)
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return indexes, nil
 }
@@ -182,18 +169,16 @@ func (c *Conn) IndexColumns(index string) ([]Column, error) {
 	}
 	defer s.Finalize()
 	var columns []Column = make([]Column, 0, 5)
-	for {
-		if ok, err := s.Next(); err != nil {
-			return nil, err
-		} else if !ok {
-			break
-		}
+	err = s.Select(func(s *Stmt) (err error) {
 		c := Column{}
-		err = s.Scan(nil, &c.Cid, &c.Name)
-		if err != nil {
-			return nil, err
+		if err = s.Scan(nil, &c.Cid, &c.Name); err != nil {
+			return
 		}
 		columns = append(columns, c)
+		return
+	})
+	if err != nil {
+		return nil, err
 	}
 	return columns, nil
 }

sqlite.go

@@ -532,7 +532,7 @@ func (s *Stmt) Exec(args ...interface{}) error {
 
 // Like Exec but returns the number of rows that were changed or inserted or deleted.
 // Don't use it with SELECT or anything that returns data.
-func (s *Stmt) ExecUpdate(args ...interface{}) (int, error) {
+func (s *Stmt) ExecDml(args ...interface{}) (int, error) {
 	err := s.Exec(args...)
 	if err != nil {
 		return -1, err
@@ -540,10 +540,10 @@ func (s *Stmt) ExecUpdate(args ...interface{}) (int, error) {
 	return s.c.Changes(), nil
 }
 
-// Like Exec but returns the autoincremented rowid.
+// Like ExecDml but returns the autoincremented rowid.
 // Don't use it with SELECT or anything that returns data.
-func (s *Stmt) ExecInsert(args ...interface{}) (int64, error) {
-	n, err := s.ExecUpdate(args...)
+func (s *Stmt) Insert(args ...interface{}) (int64, error) {
+	n, err := s.ExecDml(args...)
 	if err != nil {
 		return -1, err
 	}
@@ -553,6 +553,29 @@ func (s *Stmt) ExecInsert(args ...interface{}) (int64, error) {
 	return s.c.LastInsertRowid(), nil
 }
 
+// The callback function is invoked for each result row coming out of the statement.
+//
+//  s, err := c.Prepare(...)
+//	// TODO error handling
+//  defer s.Finalize()
+//  err = s.Select(func(s *Stmt) error {
+//  	//Scan
+//  })
+//	// TODO error handling
+func (s *Stmt) Select(rowCallbackHandler func(s *Stmt) error) error {
+	for {
+		if ok, err := s.Next(); err != nil {
+			return err
+		} else if !ok {
+			break
+		}
+		if err := rowCallbackHandler(s); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // Number of SQL parameters
 // Calls http://sqlite.org/c3ref/bind_parameter_count.html
 func (s *Stmt) BindParameterCount() int {
@@ -789,11 +812,14 @@ func (s *Stmt) ColumnType(index int) Type {
 //	defer stmt.Finalize()
 //	var id int
 //	var name string
-//	for sqlite.Must(stmt.Next()) {
-//		err = stmt.NamedScan("name", &name, "id", &id)
-//		// TODO error handling
+//  err = s.Select(func(s *Stmt) (err error) {
+//		if err = stmt.NamedScan("name", &name, "id", &id); err != nil {
+//			return
+//      }
 //		fmt.Println(id, name)
-//	}
+//  	return
+//  })
+//	// TODO error handling
 //
 // NULL value is converted to 0 if arg type is *int,*int64,*float,*float64, to "" for *string, to []byte{} for *[]byte and to false for *bool.
 // Calls sqlite3_column_count, sqlite3_column_name and sqlite3_column_(blob|double|int|int64|text) depending on args type.
@@ -827,11 +853,14 @@ func (s *Stmt) NamedScan(args ...interface{}) error {
 //	defer stmt.Finalize()
 //	var id int
 //	var name string
-//	for sqlite.Must(stmt.Next()) {
-//		err = stmt.Scan(&id, &name)
-//		// TODO error handling
+//  err = s.Select(func(s *Stmt) error {
+//		if err = stmt.Scan(&id, &name); err != nil {
+//			return
+//      }
 //		fmt.Println(id, name)
-//	}
+//  	return
+//  })
+//	// TODO error handling
 //
 // NULL value is converted to 0 if arg type is *int,*int64,*float,*float64, to "" for *string, to []byte{} for *[]byte and to false for *bool.
 // TODO How to avoid NULL conversion?

sqlite_test.go

@@ -167,7 +167,7 @@ func TestInsertWithStatement(t *testing.T) {
 
 	db.Begin()
 	for i := 0; i < 1000; i++ {
-		c, ierr := s.ExecUpdate(float64(i)*float64(3.14), i, "hello")
+		c, ierr := s.ExecDml(float64(i)*float64(3.14), i, "hello")
 		checkNoError(t, ierr, "insert error: %s")
 		if c != 1 {
 			t.Errorf("insert error: %d but got 1", c)