func()

in odps/tunnel/tunnel.go [210:296]
77 lines of code
15 McCabe index (conditional complexity)

func (t *Tunnel) Preview(table *odps.Table, partitionValue string, limit int64) ([]data.Record, error) {
	if limit < 0 {
		limit = -1
	}
	if !table.IsLoaded() {
		err := table.Load()
		if err != nil {
			return nil, err
		}
	}

	projectName := table.ProjectName()
	schemaName := table.SchemaName()
	tableName := table.Name()

	queryArgs := make(url.Values, 2)
	queryArgs.Set("limit", strconv.FormatInt(limit, 10))
	if partitionValue != "" {
		partitionValue = strings.ReplaceAll(partitionValue, "'", "")
		partitionValue = strings.ReplaceAll(partitionValue, "\"", "")
		partitionValue = strings.ReplaceAll(partitionValue, "/", ",")
		queryArgs.Set("partition", partitionValue)
	}
	resource := common.NewResourceBuilder(projectName)
	var resourceUrl string
	resourceUrl = resource.Table(schemaName, tableName)
	resourceUrl += "/preview"

	client, err := t.getRestClient(projectName)
	if err != nil {
		return nil, err
	}
	req, err := client.NewRequestWithUrlQuery(
		common.HttpMethod.GetMethod,
		resourceUrl,
		nil,
		queryArgs,
	)
	if err != nil {
		return nil, err
	}

	addCommonSessionHttpHeader(req.Header)

	req.Header.Set(common.HttpHeaderContentLength, "0")

	res, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	if res.StatusCode/100 != 2 {
		return nil, restclient.NewHttpNotOk(res)
	}

	contentEncoding := res.Header.Get(common.HttpHeaderContentEncoding)
	if contentEncoding != "" {
		res.Body = WrapByCompressor(res.Body, contentEncoding)
	}

	reader, err := ipc.NewReader(res.Body)
	if err != nil {
		return nil, err
	}
	columns := table.Schema().Columns
	partitionColumns := table.Schema().PartitionColumns
	allColumns := append(columns, partitionColumns...)

	var results []data.Record

	for {
		arrowRecord, err := reader.Read()
		isEOF := errors.Is(err, io.EOF)
		if isEOF {
			break
		}
		if err != nil {
			return nil, err
		}
		records, err := tableschema.ToMaxComputeRecords(arrowRecord, allColumns, tableschema.ArrowOptionConfig.WithExtendedMode())
		if err != nil {
			return nil, err
		}
		results = append(results, records...)
		arrowRecord.Retain()
	}
	return results, nil
}