如何通过Python在本地运行官方Google Translate API并解决凭证报错

你的客户端初始化代码存在语法错误：from_service_account_json是TranslationServiceClient的类方法，不需要先实例化类再调用。你写的TranslationServiceClient()会先触发空实例化逻辑，这个过程会自动尝试读取系统默认凭证，还没执行到后面的from_service_account_json就已经触发了凭证找不到的报错。

方案1：直接修正初始化代码（最推荐） #

把原代码里的客户端初始化行修改即可，去掉TranslationServiceClient后的括号：

# 修改前
client = translate.TranslationServiceClient().from_service_account_json('key.json')
# 修改后
client = translate.TranslationServiceClient.from_service_account_json('key.json')

修正后的完整可运行代码如下：

from google.cloud import translate
def translate_text(text="Hello, world!", project_id="weighty-site-333613"):

    client = translate.TranslationServiceClient.from_service_account_json('key.json')
    location = "global"
    parent = f"projects/{project_id}/locations/{location}"
    response = client.translate_text(
        request={
            "parent": parent,
            "contents": [text],
            "mime_type": "text/plain",
            "source_language_code": "en-US",
            "target_language_code": "zh-CN",
        }
    )

    for translation in response.translations:
        print("Translated text: {}".format(translation.translated_text))
translate_text()

方案2：配置系统环境变量 #

如果不想修改代码，可以在运行脚本前先配置环境变量，指向你的key.json绝对路径：

• macOS/Linux终端执行：export GOOGLE_APPLICATION_CREDENTIALS="/Users/jiajunmao/Documents/GitHub/translator_of_excel/key.json"
• Windows CMD执行：set GOOGLE_APPLICATION_CREDENTIALS=C:\Users\jiajunmao\Documents\GitHub\translator_of_excel\key.json
• Windows PowerShell执行：$env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\jiajunmao\Documents\GitHub\translator_of_excel\key.json"

配置完成后再运行脚本即可正常加载凭证。

建议优先使用动态拼接的绝对路径指向key.json，避免在不同工作目录运行脚本时出现文件找不到的问题，示例：

import os
from google.cloud import translate

def translate_text(text="Hello, world!", project_id="weighty-site-333613"):
    # 自动获取当前脚本同级目录下的key.json路径
    key_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'key.json')
    client = translate.TranslationServiceClient.from_service_account_json(key_path)
    location = "global"
    parent = f"projects/{project_id}/locations/{location}"
    response = client.translate_text(
        request={
            "parent": parent,
            "contents": [text],
            "mime_type": "text/plain",
            "source_language_code": "en-US",
            "target_language_code": "zh-CN",
        }
    )
    for translation in response.translations:
        print("Translated text: {}".format(translation.translated_text))

if __name__ == '__main__':
    translate_text()

内容的提问来源于stack exchange，提问作者Will_jjjjjjj