如何使用 Python 将 bigquery 返回的结果转换为 Json 格式？

Question

使用Python从Bigquery公共数据集中选取数据，得到结果后需要将其打印成JSON格式。如何将结果转换为JSON？谢谢！

已尝试row[0]但错误。

try:
    raw_results = query.rows[0]
    zipped_results = zip(field_names, raw_results)
    results = {x[0]: x[1] for x in zipped_results}
except IndexError:
    results = None

# from google.cloud import bigquery
# client = bigquery.Client()

query = """
    SELECT word, word_count
    FROM `bigquery-public-data.samples.shakespeare`
    WHERE corpus = @corpus
    AND word_count >= @min_word_count
    ORDER BY word_count DESC;
"""
query_params = [
    bigquery.ScalarQueryParameter("corpus", "STRING", "romeoandjuliet"),
    bigquery.ScalarQueryParameter("min_word_count", "INT64", 250),
]
job_config = bigquery.QueryJobConfig()
job_config.query_parameters = query_params
query_job = client.query(
    query,
    # Location must match that of the dataset(s) referenced in the 
    query.location="US",
    job_config=job_config,
)  # API request - starts the query

# Print the results
for row in query_job:
    print("{}: \t{}".format(row.word, row.word_count))
assert query_job.state == "DONE"

Answer 1

目前没有自动转换的方法，但是有一个非常简单的手动转换为 json 的方法：

records = [dict(row) for row in query_job]
json_obj = json.dumps(str(records))

另一种选择是使用熊猫进行转换：

df = query_job.to_dataframe()
json_obj = df.to_json(orient='records')

Answer 2

您实际上可以直接让 BigQuery 生成 JSON。像这样更改您的查询：

query = """
SELECT TO_JSON_STRING(word, word_count) AS json
FROM `bigquery-public-data.samples.shakespeare`
WHERE corpus = @corpus
AND word_count >= @min_word_count
ORDER BY word_count DESC;
"""

现在结果将有一个json以 JSON 格式输出命名的列。