/
sql_datasource.go
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/
sql_datasource.go
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// Copyright (C) 2021 CGI France
//
// This file is part of LINO.
//
// LINO is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// LINO is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with LINO. If not, see <http://www.gnu.org/licenses/>.
package pull
import (
"database/sql"
"fmt"
"strings"
"github.com/cgi-fr/lino/pkg/pull"
"github.com/jmoiron/sqlx"
"github.com/rs/zerolog"
"github.com/rs/zerolog/log"
"github.com/xo/dburl"
)
// SQLDataSource to read in the pull process.
type SQLDataSource struct {
url string
schema string
dbx *sqlx.DB
db *sql.DB
dialect SQLDialect
}
// Open a connection to the SQL DB
func (ds *SQLDataSource) Open() error {
db, err := dburl.Open(ds.url)
if err != nil {
return err
}
ds.db = db
u, err := dburl.Parse(ds.url)
if err != nil {
return err
}
ds.dbx = sqlx.NewDb(db, u.Unaliased)
err = ds.dbx.Ping()
if err != nil {
return err
}
return nil
}
// build table name with or without schema from dataconnector
func (ds *SQLDataSource) tableName(source pull.Table) string {
if ds.schema == "" {
return string(source.Name)
}
if strings.Contains(string(source.Name), ".") {
return string(source.Name)
}
return ds.schema + "." + string(source.Name)
}
func (ds *SQLDataSource) Read(source pull.Table, filter pull.Filter) (pull.RowSet, error) {
reader, err := ds.RowReader(source, filter)
if err != nil {
return nil, err
}
result := pull.RowSet{}
for reader.Next() {
result = append(result, reader.Value())
}
if reader.Error() != nil {
return result, fmt.Errorf("%w", reader.Error())
}
return result, nil
}
// RowReader iterate over rows in table with filter
func (ds *SQLDataSource) RowReader(source pull.Table, filter pull.Filter) (pull.RowReader, error) {
sql := &strings.Builder{}
sql.Write([]byte("SELECT "))
if filter.Distinct {
sql.Write([]byte("DISTINCT "))
}
if pcols := source.Columns; len(pcols) > 0 {
for idx := int(0); idx < len(pcols); idx++ {
if idx > 0 {
sql.Write([]byte(", "))
}
sql.Write([]byte(pcols[idx].Name))
}
} else {
sql.Write([]byte("*"))
}
sql.Write([]byte(" FROM "))
sql.Write([]byte(ds.tableName(source)))
sql.Write([]byte(" WHERE "))
whereContentFlag := false
values := []interface{}{}
for key, value := range filter.Values {
sql.Write([]byte(key))
values = append(values, value)
fmt.Fprint(sql, "=")
fmt.Fprint(sql, ds.dialect.Placeholder(len(values)))
if len(values) < len(filter.Values) {
sql.Write([]byte(" AND "))
}
whereContentFlag = true
}
if strings.TrimSpace(filter.Where) != "" {
if whereContentFlag {
sql.Write([]byte(" AND "))
}
fmt.Fprint(sql, filter.Where)
whereContentFlag = true
}
if !whereContentFlag {
sql.Write([]byte(" 1=1 "))
}
if filter.Limit > 0 {
fmt.Fprint(sql, ds.dialect.Limit(filter.Limit))
}
if log.Logger.GetLevel() <= zerolog.DebugLevel {
printSQL := sql.String()
for i, v := range values {
printSQL = strings.ReplaceAll(printSQL, ds.dialect.Placeholder(i+1), fmt.Sprintf("%v", v))
}
log.Debug().Msg(fmt.Sprint(printSQL))
}
rows, err := ds.dbx.Queryx(sql.String(), values...)
if err != nil {
return nil, err
}
return &SQLDataIterator{rows, nil, nil}, nil
}
// Close a connection to the SQL DB
func (ds *SQLDataSource) Close() error {
err := ds.dbx.Close()
if err != nil {
return err
}
return nil
}
// SQLDataIterator read data from a SQL database.
type SQLDataIterator struct {
rows *sqlx.Rows
value pull.Row
err error
}
// Next reads the next rows if it exists.
func (di *SQLDataIterator) Next() bool {
if di.rows == nil {
return false
}
if di.rows.Next() {
columns, err := di.rows.Columns()
if err != nil {
di.err = err
return false
}
values, err := di.rows.SliceScan()
if err != nil {
di.err = err
return false
}
row := pull.Row{}
for i, column := range columns {
row[column] = values[i]
}
di.value = row
return true
}
if di.rows.Err() != nil {
di.err = di.rows.Err()
}
return false
}
// Value returns the last read row.
func (di *SQLDataIterator) Value() pull.Row {
return di.value
}
// Error returns the iterator error
func (di *SQLDataIterator) Error() error {
return di.err
}
// SQLDialect to inject SQL variations
type SQLDialect interface {
// Placeholder format variable in query
Placeholder(int) string
// Limit format limitation clause
Limit(uint) string
}