| # |
| # Licensed to the Apache Software Foundation (ASF) under one or more |
| # contributor license agreements. See the NOTICE file distributed with |
| # this work for additional information regarding copyright ownership. |
| # The ASF licenses this file to You 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. |
| # |
| |
| """Tools used tool work with Avro files in the context of BigQuery. |
| |
| Classes, constants and functions in this file are experimental and have no |
| backwards compatibility guarantees. |
| |
| NOTHING IN THIS FILE HAS BACKWARDS COMPATIBILITY GUARANTEES. |
| """ |
| |
| # BigQuery types as listed in |
| # https://cloud.google.com/bigquery/docs/reference/standard-sql/data-types |
| # with aliases (RECORD, BOOLEAN, FLOAT, INTEGER) as defined in |
| # https://developers.google.com/resources/api-libraries/documentation/bigquery/v2/java/latest/com/google/api/services/bigquery/model/TableFieldSchema.html#setType-java.lang.String- |
| BIG_QUERY_TO_AVRO_TYPES = { |
| "STRUCT": "record", |
| "RECORD": "record", |
| "STRING": "string", |
| "BOOL": "boolean", |
| "BOOLEAN": "boolean", |
| "BYTES": "bytes", |
| "FLOAT64": "double", |
| "FLOAT": "double", |
| "INT64": "long", |
| "INTEGER": "long", |
| "TIME": { |
| "type": "long", |
| "logicalType": "time-micros", |
| }, |
| "TIMESTAMP": { |
| "type": "long", |
| "logicalType": "timestamp-micros", |
| }, |
| "DATE": { |
| "type": "int", |
| "logicalType": "date", |
| }, |
| "DATETIME": "string", |
| "NUMERIC": { |
| "type": "bytes", |
| "logicalType": "decimal", |
| # https://cloud.google.com/bigquery/docs/reference/standard-sql/data-types#numeric-type |
| "precision": 38, |
| "scale": 9, |
| }, |
| "GEOGRAPHY": "string", |
| } |
| |
| |
| def get_record_schema_from_dict_table_schema( |
| schema_name, table_schema, namespace="apache_beam.io.gcp.bigquery"): |
| # type: (Text, Dict[Text, Any], Text) -> Dict[Text, Any] |
| |
| """Convert a table schema into an Avro schema. |
| |
| Args: |
| schema_name (Text): The name of the record. |
| table_schema (Dict[Text, Any]): A BigQuery table schema in dict form. |
| namespace (Text): The namespace of the Avro schema. |
| |
| Returns: |
| Dict[Text, Any]: The schema as an Avro RecordSchema. |
| """ |
| avro_fields = [ |
| table_field_to_avro_field(field, ".".join((namespace, schema_name))) |
| for field in table_schema["fields"] |
| ] |
| |
| return { |
| "type": "record", |
| "name": schema_name, |
| "fields": avro_fields, |
| "doc": "Translated Avro Schema for {}".format(schema_name), |
| "namespace": namespace, |
| } |
| |
| |
| def table_field_to_avro_field(table_field, namespace): |
| # type: (Dict[Text, Any], str) -> Dict[Text, Any] |
| |
| """Convert a BigQuery field to an avro field. |
| |
| Args: |
| table_field (Dict[Text, Any]): A BigQuery field in dict form. |
| |
| Returns: |
| Dict[Text, Any]: An equivalent Avro field in dict form. |
| """ |
| assert "type" in table_field, \ |
| "Unable to get type for table field {}".format(table_field) |
| assert table_field["type"] in BIG_QUERY_TO_AVRO_TYPES, \ |
| "Unable to map BigQuery field type {} to avro type".format( |
| table_field["type"]) |
| |
| avro_type = BIG_QUERY_TO_AVRO_TYPES[table_field["type"]] |
| |
| if avro_type == "record": |
| element_type = get_record_schema_from_dict_table_schema( |
| table_field["name"], |
| table_field, |
| namespace=".".join((namespace, table_field["name"]))) |
| else: |
| element_type = avro_type |
| |
| field_mode = table_field.get("mode", "NULLABLE") |
| |
| if field_mode in (None, "NULLABLE"): |
| field_type = ["null", element_type] |
| elif field_mode == "REQUIRED": |
| field_type = element_type |
| elif field_mode == "REPEATED": |
| field_type = {"type": "array", "items": element_type} |
| else: |
| raise ValueError("Unkown BigQuery field mode: {}".format(field_mode)) |
| |
| avro_field = {"type": field_type, "name": table_field["name"]} |
| |
| doc = table_field.get("description") |
| if doc: |
| avro_field["doc"] = doc |
| |
| return avro_field |