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postgresql_query.go
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postgresql_query.go
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/*
Copyright 2022 The Dapr Authors
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package postgresql
import (
"context"
"fmt"
"strconv"
"strings"
"github.com/dapr/components-contrib/state"
"github.com/dapr/components-contrib/state/query"
"github.com/dapr/kit/logger"
"github.com/dapr/kit/ptr"
)
type Query struct {
query string
params []interface{}
limit int
skip *int64
tableName string
etagColumn string
}
func (q *Query) VisitEQ(f *query.EQ) (string, error) {
return q.whereFieldEqual(f.Key, f.Val), nil
}
func (q *Query) VisitIN(f *query.IN) (string, error) {
if len(f.Vals) == 0 {
return "", fmt.Errorf("empty IN operator for key %q", f.Key)
}
str := "("
str += q.whereFieldEqual(f.Key, f.Vals[0])
for _, v := range f.Vals[1:] {
str += " OR "
str += q.whereFieldEqual(f.Key, v)
}
str += ")"
return str, nil
}
func (q *Query) visitFilters(op string, filters []query.Filter) (string, error) {
var (
arr []string
str string
err error
)
for _, fil := range filters {
switch f := fil.(type) {
case *query.EQ:
if str, err = q.VisitEQ(f); err != nil {
return "", err
}
arr = append(arr, str)
case *query.IN:
if str, err = q.VisitIN(f); err != nil {
return "", err
}
arr = append(arr, str)
case *query.OR:
if str, err = q.VisitOR(f); err != nil {
return "", err
}
arr = append(arr, str)
case *query.AND:
if str, err = q.VisitAND(f); err != nil {
return "", err
}
arr = append(arr, str)
default:
return "", fmt.Errorf("unsupported filter type %#v", f)
}
}
sep := " " + op + " "
return "(" + strings.Join(arr, sep) + ")", nil
}
func (q *Query) VisitAND(f *query.AND) (string, error) {
return q.visitFilters("AND", f.Filters)
}
func (q *Query) VisitOR(f *query.OR) (string, error) {
return q.visitFilters("OR", f.Filters)
}
func (q *Query) Finalize(filters string, qq *query.Query) error {
q.query = fmt.Sprintf("SELECT key, value, %s as etag FROM "+q.tableName, q.etagColumn)
if filters != "" {
q.query += " WHERE " + filters
}
if len(qq.Sort) > 0 {
q.query += " ORDER BY "
for sortIndex, sortItem := range qq.Sort {
if sortIndex > 0 {
q.query += ", "
}
q.query += translateFieldToFilter(sortItem.Key)
if sortItem.Order != "" {
q.query += " " + sortItem.Order
}
}
}
if qq.Page.Limit > 0 {
q.query += " LIMIT " + strconv.Itoa(qq.Page.Limit)
q.limit = qq.Page.Limit
}
if len(qq.Page.Token) != 0 {
skip, err := strconv.ParseInt(qq.Page.Token, 10, 64)
if err != nil {
return err
}
q.query += " OFFSET " + strconv.FormatInt(skip, 10)
q.skip = &skip
}
return nil
}
func (q *Query) execute(ctx context.Context, logger logger.Logger, db dbquerier) ([]state.QueryItem, string, error) {
rows, err := db.Query(ctx, q.query, q.params...)
if err != nil {
return nil, "", err
}
defer rows.Close()
ret := []state.QueryItem{}
for rows.Next() {
var (
key string
data []byte
etag uint32
)
if err = rows.Scan(&key, &data, &etag); err != nil {
return nil, "", err
}
result := state.QueryItem{
Key: key,
Data: data,
ETag: ptr.Of(strconv.FormatUint(uint64(etag), 10)),
}
ret = append(ret, result)
}
if err = rows.Err(); err != nil {
return nil, "", err
}
var token string
if q.limit != 0 {
var skip int64
if q.skip != nil {
skip = *q.skip
}
token = strconv.FormatInt(skip+int64(len(ret)), 10)
}
return ret, token, nil
}
func (q *Query) addParamValueAndReturnPosition(value interface{}) int {
q.params = append(q.params, fmt.Sprintf("%v", value))
return len(q.params)
}
func translateFieldToFilter(key string) string {
// add preceding "value"
key = "value." + key
fieldParts := strings.Split(key, ".")
filterField := fieldParts[0]
fieldParts = fieldParts[1:]
for fieldIndex, fieldPart := range fieldParts {
filterField += "->"
if fieldIndex+1 == len(fieldParts) {
filterField += ">"
}
filterField += "'" + fieldPart + "'"
}
return filterField
}
func (q *Query) whereFieldEqual(key string, value interface{}) string {
position := q.addParamValueAndReturnPosition(value)
filterField := translateFieldToFilter(key)
query := filterField + "=$" + strconv.Itoa(position)
return query
}