1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
// Licensed to ClickHouse, Inc. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. ClickHouse, Inc. licenses this file to you 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 clickhouse
import (
"context"
"errors"
"fmt"
"reflect"
"github.com/ClickHouse/clickhouse-go/v2/lib/proto"
)
func (ch *clickhouse) Select(ctx context.Context, dest interface{}, query string, args ...interface{}) error {
value := reflect.ValueOf(dest)
if value.Kind() != reflect.Ptr {
return &OpError{
Op: "Select",
Err: errors.New("must pass a pointer, not a value, to Select destination"),
}
}
if value.IsNil() {
return &OpError{
Op: "Select",
Err: errors.New("nil pointer passed to Select destination"),
}
}
direct := reflect.Indirect(value)
if direct.Kind() != reflect.Slice {
return fmt.Errorf("must pass a slice to Select destination")
}
if direct.Len() != 0 {
// dest should point to empty slice
// to make select result correct
direct.Set(reflect.MakeSlice(direct.Type(), 0, direct.Cap()))
}
var (
base = direct.Type().Elem()
rows, err = ch.Query(ctx, query, args...)
)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
elem := reflect.New(base)
if err := rows.ScanStruct(elem.Interface()); err != nil {
return err
}
direct.Set(reflect.Append(direct, elem.Elem()))
}
if err := rows.Close(); err != nil {
return err
}
return rows.Err()
}
func scan(block *proto.Block, row int, dest ...interface{}) error {
columns := block.Columns
if len(columns) != len(dest) {
return &OpError{
Op: "Scan",
Err: fmt.Errorf("expected %d destination arguments in Scan, not %d", len(columns), len(dest)),
}
}
for i, d := range dest {
if err := columns[i].ScanRow(d, row-1); err != nil {
return &OpError{
Err: err,
ColumnName: block.ColumnsNames()[i],
}
}
}
return nil
}
|
