python - 我如何将从数据库接收到的blob数据转换为python中的图像

Question

我从数据库接收longblob数据。

我尝试将 blob 数据转换为图像并使用 cv2 读取图像。

所以我尝试将 blob 数据转换为 base64，如下面的代码，但失败了。

img = base64.decodebytes(img_str)

如何将 blob 转换为图像？ cv2 包中是否有针对此问题的转换功能？

Answer 1

您不需要 cv2 将 blob 转换为图像，您需要将 blob/图像存储在磁盘上并显示它。这里是从 mysql blob 检索到磁盘文件的示例..

祝你好运!

引用的页面网址:URL

import mysql.connector
from mysql.connector import Error

def write_file(data, filename):
    # Convert binary data to proper format and write it on Hard Disk
    with open(filename, 'wb') as file:
        file.write(data)

def readBLOB(emp_id, photo, bioData):
    print("Reading BLOB data from python_employee table")

    try:
        connection = mysql.connector.connect(host='localhost',
                                             database='python_db',
                                             user='pynative',
                                             password='pynative@#29')

        cursor = connection.cursor()
        sql_fetch_blob_query = """SELECT photo from python_employee where id = %s"""

        cursor.execute(sql_fetch_blob_query, (emp_id,))
        record = cursor.fetchall()
        for row in record:
            print("Id = ", row[0], )
            print("Name = ", row[1])
            image = row[2]
            file = row[3]
            print("Storing employee image and bio-data on disk \n")
            write_file(image, photo)
            write_file(file, bioData)

    except mysql.connector.Error as error:
        print("Failed to read BLOB data from MySQL table {}".format(error))

    finally:
        if (connection.is_connected()):
            cursor.close()
            connection.close()
            print("MySQL connection is closed")

readBLOB(1, "D:\Python\Articles\my_SQL\query_output\eric_photo.png",
         "D:\Python\Articles\my_SQL\query_output\eric_bioData.txt")
readBLOB(2, "D:\Python\Articles\my_SQL\query_output\scott_photo.png",
         "D:\Python\Articles\my_SQL\query_output\scott_bioData.txt")