forked from viant/bigquery
/
rows.go
125 lines (108 loc) · 2.78 KB
/
rows.go
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package bigquery
import (
"database/sql/driver"
"fmt"
"io"
"reflect"
"github.com/flarco/bigquery/internal"
"github.com/flarco/bigquery/internal/query"
"github.com/francoispqt/gojay"
"google.golang.org/api/bigquery/v2"
)
//Rows abstraction implements database/sql driver.Rows interface
type Rows struct {
session internal.Session
projectID string
location string
service *bigquery.Service
job *bigquery.Job
pageToken string
processedRows uint64
pageIndex int
}
//Columns returns query columns
func (r *Rows) Columns() []string {
return r.session.Columns
}
//Close closes rows
func (r *Rows) Close() error {
r.service = nil
return nil
}
//Next moves to next row
func (r *Rows) Next(dest []driver.Value) error {
if !r.hasNext() {
return io.EOF
}
if r.pageIndex >= len(r.session.Rows) {
if err := r.fetchPage(); err != nil {
return err
}
}
region := r.session.Rows[r.pageIndex]
data := r.session.Data[region.Begin:region.End]
err := gojay.UnmarshalJSONArray(data, r.session.Decoder)
if err != nil {
return err
}
for i := range r.session.Pointers {
dest[i] = r.session.XTypes[i].Deref(r.session.Pointers[i])
}
r.pageIndex++
r.processedRows++
return nil
}
//hasNext returns true if there is next row to fetch.
func (r *Rows) hasNext() bool {
return r.processedRows < r.session.TotalRows
}
func (r *Rows) init() error {
response, err := r.queryResult()
if err != nil {
return err
}
r.pageToken = response.PageToken
return nil
}
func (r *Rows) fetchPage() error {
response, err := r.queryResult()
if err != nil {
return err
}
r.pageToken = response.PageToken
r.pageIndex = 0
return nil
}
func (r *Rows) queryResult() (*query.Response, error) {
call := r.service.Jobs.GetQueryResults(r.projectID, r.job.JobReference.JobId)
call.Location(r.location)
queryCall := query.NewResultsCall(call, &r.session)
call.PageToken(r.pageToken)
response, err := queryCall.Do()
return response, err
}
//ColumnTypeScanType returns column scan type
func (r *Rows) ColumnTypeScanType(index int) reflect.Type {
return r.session.DestTypes[index]
}
//ColumnTypeDatabaseTypeName returns column database type name
func (r *Rows) ColumnTypeDatabaseTypeName(index int) string {
return r.session.Schema.Fields[index].Type
}
//ColumnTypeNullable returns if column is nullable
func (r *Rows) ColumnTypeNullable(index int) (nullable, ok bool) {
isNullable := r.session.Schema.Fields[index].Mode == "NULLABLE"
return isNullable, true
}
func newRows(service *bigquery.Service, projectID string, location string, job *bigquery.Job) (*Rows, error) {
if service == nil {
return nil, fmt.Errorf("service was nil")
}
var result = &Rows{
service: service,
job: job,
location: location,
projectID: projectID,
}
return result, result.init()
}