使用 Python 将 BigQuery 架构表转换为 json

Question

我需要这个 BigQuery 的 Python 等效项bq show --format=prettyjson myproject:mydataset.mytable。

有没有办法在 Python 中使用 BigQuery API 来做到这一点？

我在Python中尝试过这个：

view_ref = self._client.dataset(dataset.dataset_id).table(table.table_id)
table_obj = self._client.get_table(view_ref)

dict_schema = []
for schema_field in table_obj.schema:
    dict_schema.append({
        'name': schema_field.name,
        'mode': schema_field.mode,
        'type': schema_field.field_type
   })

几乎可以用了；我只是没有嵌套架构字段/

感谢您的回复，祝您有美好的一天。

Answer 1

您只需使用schema_to_json()方法即可将表架构转换为 json 。它需要两个属性，分别是schema_list和destination。

我使用带有嵌套数据的公共数据集举例说明了您的案例，并使用StringIO()只是为了展示架构的样子。

from google.cloud import bigquery
import io

client = bigquery.Client()

project = 'bigquery-public-data'
dataset_id = 'samples'
table_id = 'shakespeare'

dataset_ref = client.dataset(dataset_id, project=project)
table_ref = dataset_ref.table(table_id)
table = client.get_table(table_ref)


f = io.StringIO("")
client.schema_to_json(table.schema, f)
print(f.getvalue())

和输出：

[
  {
    "description": "A single unique word (where whitespace is the delimiter) extracted from a corpus.",
    "mode": "REQUIRED",
    "name": "word",
    "type": "STRING"
  },
  {
    "description": "The number of times this word appears in this corpus.",
    "mode": "REQUIRED",
    "name": "word_count",
    "type": "INTEGER"
  },
  {
    "description": "The work from which this word was extracted.",
    "mode": "REQUIRED",
    "name": "corpus",
    "type": "STRING"
  },
  {
    "description": "The year in which this corpus was published.",
    "mode": "REQUIRED",
    "name": "corpus_date",
    "type": "INTEGER"
  }
]

与使用命令时显示的输出相同!bq show --format=prettyjson bigquery-public-data:samples.wikipedia | jq '.schema.fields'