/
BQTableSchemaToProtoDescriptor.java
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/
BQTableSchemaToProtoDescriptor.java
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/*
* Copyright 2020 Google LLC
*
* 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
*
* https://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 com.google.cloud.bigquery.storage.v1;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.protobuf.DescriptorProtos.DescriptorProto;
import com.google.protobuf.DescriptorProtos.FieldDescriptorProto;
import com.google.protobuf.DescriptorProtos.FileDescriptorProto;
import com.google.protobuf.Descriptors;
import com.google.protobuf.Descriptors.Descriptor;
import com.google.protobuf.Descriptors.FileDescriptor;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
/**
* Converts a BQ table schema to protobuf descriptor. All field names will be converted to lowercase
* when constructing the protobuf descriptor. The mapping between field types and field modes are
* shown in the ImmutableMaps below.
*/
public class BQTableSchemaToProtoDescriptor {
private static ImmutableMap<TableFieldSchema.Mode, FieldDescriptorProto.Label>
BQTableSchemaModeMap =
ImmutableMap.of(
TableFieldSchema.Mode.NULLABLE, FieldDescriptorProto.Label.LABEL_OPTIONAL,
TableFieldSchema.Mode.REPEATED, FieldDescriptorProto.Label.LABEL_REPEATED,
TableFieldSchema.Mode.REQUIRED, FieldDescriptorProto.Label.LABEL_REQUIRED);
private static ImmutableMap<TableFieldSchema.Type, FieldDescriptorProto.Type>
BQTableSchemaTypeMap =
new ImmutableMap.Builder<TableFieldSchema.Type, FieldDescriptorProto.Type>()
.put(TableFieldSchema.Type.BOOL, FieldDescriptorProto.Type.TYPE_BOOL)
.put(TableFieldSchema.Type.BYTES, FieldDescriptorProto.Type.TYPE_BYTES)
.put(TableFieldSchema.Type.DATE, FieldDescriptorProto.Type.TYPE_INT32)
.put(TableFieldSchema.Type.DATETIME, FieldDescriptorProto.Type.TYPE_INT64)
.put(TableFieldSchema.Type.DOUBLE, FieldDescriptorProto.Type.TYPE_DOUBLE)
.put(TableFieldSchema.Type.GEOGRAPHY, FieldDescriptorProto.Type.TYPE_STRING)
.put(TableFieldSchema.Type.INT64, FieldDescriptorProto.Type.TYPE_INT64)
.put(TableFieldSchema.Type.NUMERIC, FieldDescriptorProto.Type.TYPE_BYTES)
.put(TableFieldSchema.Type.BIGNUMERIC, FieldDescriptorProto.Type.TYPE_BYTES)
.put(TableFieldSchema.Type.STRING, FieldDescriptorProto.Type.TYPE_STRING)
.put(TableFieldSchema.Type.STRUCT, FieldDescriptorProto.Type.TYPE_MESSAGE)
.put(TableFieldSchema.Type.TIME, FieldDescriptorProto.Type.TYPE_INT64)
.put(TableFieldSchema.Type.TIMESTAMP, FieldDescriptorProto.Type.TYPE_INT64)
.put(TableFieldSchema.Type.JSON, FieldDescriptorProto.Type.TYPE_STRING)
.put(TableFieldSchema.Type.INTERVAL, FieldDescriptorProto.Type.TYPE_STRING)
.build();
/**
* Converts TableFieldSchema to a Descriptors.Descriptor object.
*
* @param BQTableSchema
* @throws Descriptors.DescriptorValidationException
*/
public static Descriptor convertBQTableSchemaToProtoDescriptor(TableSchema BQTableSchema)
throws Descriptors.DescriptorValidationException {
Preconditions.checkNotNull(BQTableSchema, "BQTableSchema is null.");
return convertBQTableSchemaToProtoDescriptorImpl(
BQTableSchema, "root", new HashMap<ImmutableList<TableFieldSchema>, Descriptor>());
}
/**
* Converts a TableFieldSchema to a Descriptors.Descriptor object.
*
* @param BQTableSchema
* @param scope Keeps track of current scope to prevent repeated naming while constructing
* descriptor.
* @param dependencyMap Stores already constructed descriptors to prevent reconstruction
* @throws Descriptors.DescriptorValidationException
*/
private static Descriptor convertBQTableSchemaToProtoDescriptorImpl(
TableSchema BQTableSchema,
String scope,
HashMap<ImmutableList<TableFieldSchema>, Descriptor> dependencyMap)
throws Descriptors.DescriptorValidationException {
List<FileDescriptor> dependenciesList = new ArrayList<FileDescriptor>();
List<FieldDescriptorProto> fields = new ArrayList<FieldDescriptorProto>();
int index = 1;
for (TableFieldSchema BQTableField : BQTableSchema.getFieldsList()) {
String currentScope = scope + "__" + BQTableField.getName();
if (BQTableField.getType() == TableFieldSchema.Type.STRUCT) {
ImmutableList<TableFieldSchema> fieldList =
ImmutableList.copyOf(BQTableField.getFieldsList());
if (dependencyMap.containsKey(fieldList)) {
Descriptor descriptor = dependencyMap.get(fieldList);
dependenciesList.add(descriptor.getFile());
fields.add(convertBQTableFieldToProtoField(BQTableField, index++, descriptor.getName()));
} else {
Descriptor descriptor =
convertBQTableSchemaToProtoDescriptorImpl(
TableSchema.newBuilder().addAllFields(fieldList).build(),
currentScope,
dependencyMap);
dependenciesList.add(descriptor.getFile());
dependencyMap.put(fieldList, descriptor);
fields.add(convertBQTableFieldToProtoField(BQTableField, index++, currentScope));
}
} else {
fields.add(convertBQTableFieldToProtoField(BQTableField, index++, currentScope));
}
}
FileDescriptor[] dependenciesArray = new FileDescriptor[dependenciesList.size()];
dependenciesArray = dependenciesList.toArray(dependenciesArray);
DescriptorProto descriptorProto =
DescriptorProto.newBuilder().setName(scope).addAllField(fields).build();
FileDescriptorProto fileDescriptorProto =
FileDescriptorProto.newBuilder().addMessageType(descriptorProto).build();
FileDescriptor fileDescriptor =
FileDescriptor.buildFrom(fileDescriptorProto, dependenciesArray);
Descriptor descriptor = fileDescriptor.findMessageTypeByName(scope);
return descriptor;
}
/**
* Converts a BQTableField to ProtoField
*
* @param BQTableField BQ Field used to construct a FieldDescriptorProto
* @param index Index for protobuf fields.
* @param scope used to name descriptors
*/
private static FieldDescriptorProto convertBQTableFieldToProtoField(
TableFieldSchema BQTableField, int index, String scope) {
TableFieldSchema.Mode mode = BQTableField.getMode();
String fieldName = BQTableField.getName().toLowerCase();
if (BQTableField.getType() == TableFieldSchema.Type.STRUCT) {
return FieldDescriptorProto.newBuilder()
.setName(fieldName)
.setTypeName(scope)
.setLabel((FieldDescriptorProto.Label) BQTableSchemaModeMap.get(mode))
.setNumber(index)
.build();
}
return FieldDescriptorProto.newBuilder()
.setName(fieldName)
.setType((FieldDescriptorProto.Type) BQTableSchemaTypeMap.get(BQTableField.getType()))
.setLabel((FieldDescriptorProto.Label) BQTableSchemaModeMap.get(mode))
.setNumber(index)
.build();
}
}