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query.go
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query.go
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package clickhouse
import (
"errors"
"strings"
"net/url"
"encoding/json"
)
type External struct {
Name string
Structure string
Data []byte
}
type Func struct {
Name string
Args interface{}
}
type Query struct {
Stmt string
args []interface{}
externals []External
params url.Values
}
// Adding external dictionary
func (q *Query) AddExternal(name string, structure string, data []byte) {
q.externals = append(q.externals, External{Name: name, Structure: structure, Data: data})
}
// Additional parameters like: max_memory_usage, etc.
func (q Query) AddParam(name string, value string) {
q.params.Add(name, value)
}
func (q Query) MergeParams(params url.Values) {
for key, value := range params {
if q.params.Get(key) == "" {
q.params.Set(key, value[0])
}
}
}
func (q Query) Iter(conn *Conn) *Iter {
if conn == nil {
return &Iter{err: errors.New("Connection pointer is nil")}
}
resp, err := conn.transport.Exec(conn, q, false)
if err != nil {
return &Iter{err: err}
}
err = errorFromResponse(resp)
if err != nil {
return &Iter{err: err}
}
return &Iter{text: resp}
}
func (r *Iter) Len() int {
return len(r.text)
}
func (q Query) Exec(conn *Conn) (err error) {
if conn == nil {
return errors.New("Connection pointer is nil")
}
resp, err := conn.transport.Exec(conn, q, false)
if err == nil {
err = errorFromResponse(resp)
}
return err
}
func (q Query) ExecScan(conn *Conn, obj interface{}) (error) {
if conn == nil {
return errors.New("Connection pointer is nil")
}
q.Stmt += " FORMAT JSON"
resp, err := conn.transport.Exec(conn, q, false)
if err == nil {
err = errorFromResponse(resp)
}
if err == nil {
var readObj struct{
Data json.RawMessage `json:"data"`
}
errUnmarshal := json.Unmarshal([]byte(resp), &readObj)
if errUnmarshal != nil {
return errUnmarshal
}
errUnmarshalObj := json.Unmarshal(readObj.Data, &obj)
if errUnmarshalObj != nil {
return errUnmarshalObj
}
}
return err
}
type Iter struct {
err error
text string
}
func (r *Iter) Error() error {
return r.err
}
func (r *Iter) Scan(vars ...interface{}) bool {
row := r.fetchNext()
if len(row) == 0 {
return false
}
a := strings.Split(row, "\t")
if len(a) < len(vars) {
return false
}
for i, v := range vars {
err := unmarshal(v, a[i])
if err != nil {
r.err = err
return false
}
}
return true
}
func (r *Iter) fetchNext() string {
var res string
pos := strings.Index(r.text, "\n")
if pos == -1 {
res = r.text
r.text = ""
} else {
res = r.text[:pos]
r.text = r.text[pos+1:]
}
return res
}