import gridfs
import pymongo
from bson import ObjectId
from gridfs import GridFS

DB_HOST = "116.63.130.34"
DB_PASS = "UTlC9cCoglD1cI1*"
DB_USER = "root"
DB_PORT = "27021"
client = pymongo.MongoClient('mongodb://{}:{}@{}:{}'.format(DB_USER, DB_PASS, DB_HOST, DB_PORT))


def FIND_FILE(bucket, file_id):
    """
    读取一个文件
    Parameters:
        bucket: 文件存储桶
        file_id: 文件ID
    Returns:
        data 成功: 文件二进制; 失败: None
    """
    # 实例化一个文件存储器
    gfs = GridFS(client['文件'], collection=bucket)
    try:
        # 二进制读取文件
        data = gfs.get(ObjectId(file_id)).read()
        # 返回文件二进制流
        return data
    except gridfs.errors.NoFile:
        return None