bigquery/extract.go

// Copyright 2016 Google Inc. All Rights Reserved.
//
// 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 bigquery

import (
	"golang.org/x/net/context"
	bq "google.golang.org/api/bigquery/v2"
)

// ExtractConfig holds the configuration for an extract job.
type ExtractConfig struct {
	// JobID is the ID to use for the extract job. If empty, a job ID will be automatically created.
	JobID string

	// Src is the table from which data will be extracted.
	Src *Table

	// Dst is the destination into which the data will be extracted.
	Dst *GCSReference

	// DisableHeader disables the printing of a header row in exported data.
	DisableHeader bool
}

// An Extractor extracts data from a BigQuery table into Google Cloud Storage.
type Extractor struct {
	ExtractConfig
	c *Client
}

// ExtractorTo returns an Extractor which can be used to extract data from a
// BigQuery table into Google Cloud Storage.
// The returned Extractor may optionally be further configured before its Run method is called.
func (t *Table) ExtractorTo(dst *GCSReference) *Extractor {
	return &Extractor{
		c: t.c,
		ExtractConfig: ExtractConfig{
			Src: t,
			Dst: dst,
		},
	}
}

// Run initiates an extract job.
func (e *Extractor) Run(ctx context.Context) (*Job, error) {
	conf := &bq.JobConfigurationExtract{}
	job := &bq.Job{Configuration: &bq.JobConfiguration{Extract: conf}}

	setJobRef(job, e.JobID, e.c.projectID)

	conf.DestinationUris = append([]string{}, e.Dst.uris...)
	conf.Compression = string(e.Dst.Compression)
	conf.DestinationFormat = string(e.Dst.DestinationFormat)
	conf.FieldDelimiter = e.Dst.FieldDelimiter

	conf.SourceTable = e.Src.tableRefProto()

	if e.DisableHeader {
		f := false
		conf.PrintHeader = &f
	}

	return e.c.insertJob(ctx, &insertJobConf{job: job})
}