145 lines
4 KiB
Go
145 lines
4 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package bigquery
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import (
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"errors"
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"fmt"
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"strconv"
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"time"
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bq "google.golang.org/api/bigquery/v2"
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)
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// Value stores the contents of a single cell from a BigQuery result.
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type Value interface{}
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// ValueLoader stores a slice of Values representing a result row from a Read operation.
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// See Iterator.Get for more information.
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type ValueLoader interface {
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Load(v []Value) error
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}
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// ValueList converts a []Value to implement ValueLoader.
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type ValueList []Value
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// Load stores a sequence of values in a ValueList.
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func (vs *ValueList) Load(v []Value) error {
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*vs = append(*vs, v...)
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return nil
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}
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// convertRows converts a series of TableRows into a series of Value slices.
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// schema is used to interpret the data from rows; its length must match the
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// length of each row.
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func convertRows(rows []*bq.TableRow, schema Schema) ([][]Value, error) {
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var rs [][]Value
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for _, r := range rows {
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row, err := convertRow(r, schema)
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if err != nil {
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return nil, err
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}
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rs = append(rs, row)
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}
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return rs, nil
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}
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func convertRow(r *bq.TableRow, schema Schema) ([]Value, error) {
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if len(schema) != len(r.F) {
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return nil, errors.New("schema length does not match row length")
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}
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var values []Value
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for i, cell := range r.F {
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fs := schema[i]
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v, err := convertValue(cell.V, fs.Type, fs.Schema)
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if err != nil {
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return nil, err
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}
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values = append(values, v)
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}
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return values, nil
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}
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func convertValue(val interface{}, typ FieldType, schema Schema) (Value, error) {
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switch val := val.(type) {
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case nil:
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return nil, nil
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case []interface{}:
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return convertRepeatedRecord(val, typ, schema)
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case map[string]interface{}:
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return convertNestedRecord(val, schema)
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case string:
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return convertBasicType(val, typ)
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default:
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return nil, fmt.Errorf("got value %v; expected a value of type %s", val, typ)
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}
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}
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func convertRepeatedRecord(vals []interface{}, typ FieldType, schema Schema) (Value, error) {
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var values []Value
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for _, cell := range vals {
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// each cell contains a single entry, keyed by "v"
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val := cell.(map[string]interface{})["v"]
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v, err := convertValue(val, typ, schema)
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if err != nil {
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return nil, err
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}
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values = append(values, v)
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}
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return values, nil
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}
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func convertNestedRecord(val map[string]interface{}, schema Schema) (Value, error) {
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// convertNestedRecord is similar to convertRow, as a record has the same structure as a row.
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// Nested records are wrapped in a map with a single key, "f".
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record := val["f"].([]interface{})
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if len(record) != len(schema) {
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return nil, errors.New("schema length does not match record length")
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}
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var values []Value
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for i, cell := range record {
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// each cell contains a single entry, keyed by "v"
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val := cell.(map[string]interface{})["v"]
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fs := schema[i]
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v, err := convertValue(val, fs.Type, fs.Schema)
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if err != nil {
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return nil, err
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}
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values = append(values, v)
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}
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return values, nil
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}
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// convertBasicType returns val as an interface with a concrete type specified by typ.
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func convertBasicType(val string, typ FieldType) (Value, error) {
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switch typ {
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case StringFieldType:
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return val, nil
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case IntegerFieldType:
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return strconv.Atoi(val)
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case FloatFieldType:
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return strconv.ParseFloat(val, 64)
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case BooleanFieldType:
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return strconv.ParseBool(val)
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case TimestampFieldType:
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f, err := strconv.ParseFloat(val, 64)
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return Value(time.Unix(0, int64(f*1e9))), err
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default:
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return nil, errors.New("unrecognized type")
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}
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}
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