388 lines
11 KiB
Go
388 lines
11 KiB
Go
// Copyright 2015 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 (
|
|
"errors"
|
|
"fmt"
|
|
"reflect"
|
|
|
|
"cloud.google.com/go/internal/atomiccache"
|
|
bq "google.golang.org/api/bigquery/v2"
|
|
)
|
|
|
|
// Schema describes the fields in a table or query result.
|
|
type Schema []*FieldSchema
|
|
|
|
type FieldSchema struct {
|
|
// The field name.
|
|
// Must contain only letters (a-z, A-Z), numbers (0-9), or underscores (_),
|
|
// and must start with a letter or underscore.
|
|
// The maximum length is 128 characters.
|
|
Name string
|
|
|
|
// A description of the field. The maximum length is 16,384 characters.
|
|
Description string
|
|
|
|
// Whether the field may contain multiple values.
|
|
Repeated bool
|
|
// Whether the field is required. Ignored if Repeated is true.
|
|
Required bool
|
|
|
|
// The field data type. If Type is Record, then this field contains a nested schema,
|
|
// which is described by Schema.
|
|
Type FieldType
|
|
// Describes the nested schema if Type is set to Record.
|
|
Schema Schema
|
|
}
|
|
|
|
func (fs *FieldSchema) toBQ() *bq.TableFieldSchema {
|
|
tfs := &bq.TableFieldSchema{
|
|
Description: fs.Description,
|
|
Name: fs.Name,
|
|
Type: string(fs.Type),
|
|
}
|
|
|
|
if fs.Repeated {
|
|
tfs.Mode = "REPEATED"
|
|
} else if fs.Required {
|
|
tfs.Mode = "REQUIRED"
|
|
} // else leave as default, which is interpreted as NULLABLE.
|
|
|
|
for _, f := range fs.Schema {
|
|
tfs.Fields = append(tfs.Fields, f.toBQ())
|
|
}
|
|
|
|
return tfs
|
|
}
|
|
|
|
func (s Schema) toBQ() *bq.TableSchema {
|
|
var fields []*bq.TableFieldSchema
|
|
for _, f := range s {
|
|
fields = append(fields, f.toBQ())
|
|
}
|
|
return &bq.TableSchema{Fields: fields}
|
|
}
|
|
|
|
func bqToFieldSchema(tfs *bq.TableFieldSchema) *FieldSchema {
|
|
fs := &FieldSchema{
|
|
Description: tfs.Description,
|
|
Name: tfs.Name,
|
|
Repeated: tfs.Mode == "REPEATED",
|
|
Required: tfs.Mode == "REQUIRED",
|
|
Type: FieldType(tfs.Type),
|
|
}
|
|
|
|
for _, f := range tfs.Fields {
|
|
fs.Schema = append(fs.Schema, bqToFieldSchema(f))
|
|
}
|
|
return fs
|
|
}
|
|
|
|
func bqToSchema(ts *bq.TableSchema) Schema {
|
|
if ts == nil {
|
|
return nil
|
|
}
|
|
var s Schema
|
|
for _, f := range ts.Fields {
|
|
s = append(s, bqToFieldSchema(f))
|
|
}
|
|
return s
|
|
}
|
|
|
|
type FieldType string
|
|
|
|
const (
|
|
StringFieldType FieldType = "STRING"
|
|
BytesFieldType FieldType = "BYTES"
|
|
IntegerFieldType FieldType = "INTEGER"
|
|
FloatFieldType FieldType = "FLOAT"
|
|
BooleanFieldType FieldType = "BOOLEAN"
|
|
TimestampFieldType FieldType = "TIMESTAMP"
|
|
RecordFieldType FieldType = "RECORD"
|
|
DateFieldType FieldType = "DATE"
|
|
TimeFieldType FieldType = "TIME"
|
|
DateTimeFieldType FieldType = "DATETIME"
|
|
)
|
|
|
|
var (
|
|
errNoStruct = errors.New("bigquery: can only infer schema from struct or pointer to struct")
|
|
errUnsupportedFieldType = errors.New("bigquery: unsupported type of field in struct")
|
|
errInvalidFieldName = errors.New("bigquery: invalid name of field in struct")
|
|
errBadNullable = errors.New(`bigquery: use "nullable" only for []byte and struct pointers; for all other types, use a NullXXX type`)
|
|
)
|
|
|
|
var typeOfByteSlice = reflect.TypeOf([]byte{})
|
|
|
|
// InferSchema tries to derive a BigQuery schema from the supplied struct value.
|
|
// Each exported struct field is mapped to a field in the schema.
|
|
//
|
|
// The following BigQuery types are inferred from the corresponding Go types.
|
|
// (This is the same mapping as that used for RowIterator.Next.) Fields inferred
|
|
// from these types are marked required (non-nullable).
|
|
//
|
|
// STRING string
|
|
// BOOL bool
|
|
// INTEGER int, int8, int16, int32, int64, uint8, uint16, uint32
|
|
// FLOAT float32, float64
|
|
// BYTES []byte
|
|
// TIMESTAMP time.Time
|
|
// DATE civil.Date
|
|
// TIME civil.Time
|
|
// DATETIME civil.DateTime
|
|
//
|
|
// A Go slice or array type is inferred to be a BigQuery repeated field of the
|
|
// element type. The element type must be one of the above listed types.
|
|
//
|
|
// Nullable fields are inferred from the NullXXX types, declared in this package:
|
|
//
|
|
// STRING NullString
|
|
// BOOL NullBool
|
|
// INTEGER NullInt64
|
|
// FLOAT NullFloat64
|
|
// TIMESTAMP NullTimestamp
|
|
// DATE NullDate
|
|
// TIME NullTime
|
|
// DATETIME NullDateTime
|
|
|
|
// For a nullable BYTES field, use the type []byte and tag the field "nullable" (see below).
|
|
//
|
|
// A struct field that is of struct type is inferred to be a required field of type
|
|
// RECORD with a schema inferred recursively. For backwards compatibility, a field of
|
|
// type pointer to struct is also inferred to be required. To get a nullable RECORD
|
|
// field, use the "nullable" tag (see below).
|
|
//
|
|
// InferSchema returns an error if any of the examined fields is of type uint,
|
|
// uint64, uintptr, map, interface, complex64, complex128, func, or chan. Future
|
|
// versions may handle these cases without error.
|
|
//
|
|
// Recursively defined structs are also disallowed.
|
|
//
|
|
// Struct fields may be tagged in a way similar to the encoding/json package.
|
|
// A tag of the form
|
|
// bigquery:"name"
|
|
// uses "name" instead of the struct field name as the BigQuery field name.
|
|
// A tag of the form
|
|
// bigquery:"-"
|
|
// omits the field from the inferred schema.
|
|
// The "nullable" option marks the field as nullable (not required). It is only
|
|
// needed for []byte and pointer-to-struct fields, and cannot appear on other
|
|
// fields. In this example, the Go name of the field is retained:
|
|
// bigquery:",nullable"
|
|
func InferSchema(st interface{}) (Schema, error) {
|
|
return inferSchemaReflectCached(reflect.TypeOf(st))
|
|
}
|
|
|
|
// TODO(jba): replace with sync.Map for Go 1.9.
|
|
var schemaCache atomiccache.Cache
|
|
|
|
type cacheVal struct {
|
|
schema Schema
|
|
err error
|
|
}
|
|
|
|
func inferSchemaReflectCached(t reflect.Type) (Schema, error) {
|
|
cv := schemaCache.Get(t, func() interface{} {
|
|
s, err := inferSchemaReflect(t)
|
|
return cacheVal{s, err}
|
|
}).(cacheVal)
|
|
return cv.schema, cv.err
|
|
}
|
|
|
|
func inferSchemaReflect(t reflect.Type) (Schema, error) {
|
|
rec, err := hasRecursiveType(t, nil)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if rec {
|
|
return nil, fmt.Errorf("bigquery: schema inference for recursive type %s", t)
|
|
}
|
|
return inferStruct(t)
|
|
}
|
|
|
|
func inferStruct(t reflect.Type) (Schema, error) {
|
|
switch t.Kind() {
|
|
case reflect.Ptr:
|
|
if t.Elem().Kind() != reflect.Struct {
|
|
return nil, errNoStruct
|
|
}
|
|
t = t.Elem()
|
|
fallthrough
|
|
|
|
case reflect.Struct:
|
|
return inferFields(t)
|
|
default:
|
|
return nil, errNoStruct
|
|
}
|
|
}
|
|
|
|
// inferFieldSchema infers the FieldSchema for a Go type
|
|
func inferFieldSchema(rt reflect.Type, nullable bool) (*FieldSchema, error) {
|
|
// Only []byte and struct pointers can be tagged nullable.
|
|
if nullable && !(rt == typeOfByteSlice || rt.Kind() == reflect.Ptr && rt.Elem().Kind() == reflect.Struct) {
|
|
return nil, errBadNullable
|
|
}
|
|
switch rt {
|
|
case typeOfByteSlice:
|
|
return &FieldSchema{Required: !nullable, Type: BytesFieldType}, nil
|
|
case typeOfGoTime:
|
|
return &FieldSchema{Required: true, Type: TimestampFieldType}, nil
|
|
case typeOfDate:
|
|
return &FieldSchema{Required: true, Type: DateFieldType}, nil
|
|
case typeOfTime:
|
|
return &FieldSchema{Required: true, Type: TimeFieldType}, nil
|
|
case typeOfDateTime:
|
|
return &FieldSchema{Required: true, Type: DateTimeFieldType}, nil
|
|
}
|
|
if ft := nullableFieldType(rt); ft != "" {
|
|
return &FieldSchema{Required: false, Type: ft}, nil
|
|
}
|
|
if isSupportedIntType(rt) || isSupportedUintType(rt) {
|
|
return &FieldSchema{Required: true, Type: IntegerFieldType}, nil
|
|
}
|
|
switch rt.Kind() {
|
|
case reflect.Slice, reflect.Array:
|
|
et := rt.Elem()
|
|
if et != typeOfByteSlice && (et.Kind() == reflect.Slice || et.Kind() == reflect.Array) {
|
|
// Multi dimensional slices/arrays are not supported by BigQuery
|
|
return nil, errUnsupportedFieldType
|
|
}
|
|
if nullableFieldType(et) != "" {
|
|
// Repeated nullable types are not supported by BigQuery.
|
|
return nil, errUnsupportedFieldType
|
|
}
|
|
f, err := inferFieldSchema(et, false)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
f.Repeated = true
|
|
f.Required = false
|
|
return f, nil
|
|
case reflect.Ptr:
|
|
if rt.Elem().Kind() != reflect.Struct {
|
|
return nil, errUnsupportedFieldType
|
|
}
|
|
fallthrough
|
|
case reflect.Struct:
|
|
nested, err := inferStruct(rt)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &FieldSchema{Required: !nullable, Type: RecordFieldType, Schema: nested}, nil
|
|
case reflect.String:
|
|
return &FieldSchema{Required: !nullable, Type: StringFieldType}, nil
|
|
case reflect.Bool:
|
|
return &FieldSchema{Required: !nullable, Type: BooleanFieldType}, nil
|
|
case reflect.Float32, reflect.Float64:
|
|
return &FieldSchema{Required: !nullable, Type: FloatFieldType}, nil
|
|
default:
|
|
return nil, errUnsupportedFieldType
|
|
}
|
|
}
|
|
|
|
// inferFields extracts all exported field types from struct type.
|
|
func inferFields(rt reflect.Type) (Schema, error) {
|
|
var s Schema
|
|
fields, err := fieldCache.Fields(rt)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
for _, field := range fields {
|
|
var nullable bool
|
|
for _, opt := range field.ParsedTag.([]string) {
|
|
if opt == nullableTagOption {
|
|
nullable = true
|
|
break
|
|
}
|
|
}
|
|
f, err := inferFieldSchema(field.Type, nullable)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
f.Name = field.Name
|
|
s = append(s, f)
|
|
}
|
|
return s, nil
|
|
}
|
|
|
|
// isSupportedIntType reports whether t is an int type that can be properly
|
|
// represented by the BigQuery INTEGER/INT64 type.
|
|
func isSupportedIntType(t reflect.Type) bool {
|
|
switch t.Kind() {
|
|
case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
|
|
return true
|
|
default:
|
|
return false
|
|
}
|
|
}
|
|
|
|
// isSupportedIntType reports whether t is a uint type that can be properly
|
|
// represented by the BigQuery INTEGER/INT64 type.
|
|
func isSupportedUintType(t reflect.Type) bool {
|
|
switch t.Kind() {
|
|
case reflect.Uint8, reflect.Uint16, reflect.Uint32:
|
|
return true
|
|
default:
|
|
return false
|
|
}
|
|
}
|
|
|
|
// typeList is a linked list of reflect.Types.
|
|
type typeList struct {
|
|
t reflect.Type
|
|
next *typeList
|
|
}
|
|
|
|
func (l *typeList) has(t reflect.Type) bool {
|
|
for l != nil {
|
|
if l.t == t {
|
|
return true
|
|
}
|
|
l = l.next
|
|
}
|
|
return false
|
|
}
|
|
|
|
// hasRecursiveType reports whether t or any type inside t refers to itself, directly or indirectly,
|
|
// via exported fields. (Schema inference ignores unexported fields.)
|
|
func hasRecursiveType(t reflect.Type, seen *typeList) (bool, error) {
|
|
for t.Kind() == reflect.Ptr || t.Kind() == reflect.Slice || t.Kind() == reflect.Array {
|
|
t = t.Elem()
|
|
}
|
|
if t.Kind() != reflect.Struct {
|
|
return false, nil
|
|
}
|
|
if seen.has(t) {
|
|
return true, nil
|
|
}
|
|
fields, err := fieldCache.Fields(t)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
seen = &typeList{t, seen}
|
|
// Because seen is a linked list, additions to it from one field's
|
|
// recursive call will not affect the value for subsequent fields' calls.
|
|
for _, field := range fields {
|
|
ok, err := hasRecursiveType(field.Type, seen)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
if ok {
|
|
return true, nil
|
|
}
|
|
}
|
|
return false, nil
|
|
}
|