要求

我正在尝试从数据库中检索图像并将此图像设置为 kivy 图像小部件，此操作会引发 ValueError，不确定原因.欢迎任何意见.

数据库:Sqlite3

表名:用户

列:用户 ID、用户名、用户图像

 def populate_fields(self): # NEW# 代码在此处检索文本数据并显示在文本输入字段中.# 第 1 步:检索图像连接 = sqlite3.connect("demo.db")有连接:游标 = 连接.游标()cursor.execute("从用户那里选择 UserImageUserID=?",self.data_items[columns[0]]['text'])图像 = cursor.fetchone()数据 = io.BytesIO(图像[0])#STEP 2:将输出设置为图像小部件self.image.source = 数据 # --->触发错误

错误追溯:

self.image.source = 数据文件kivyweakproxy.pyx"，第 33 行，在 kivy.weakproxy.WeakProxy.__setattr__ (kivyweakproxy.c:1471)文件kivyproperties.pyx"，第 478 行，在 kivy.properties.Property.__set__ (kivyproperties.c:5572)文件kivyproperties.pyx"，第 513 行，在 kivy.properties.Property.set (kivyproperties.c:6352)文件kivyproperties.pyx"，第 504 行，在 kivy.properties.Property.set (kivyproperties.c:6173)文件kivyproperties.pyx"，第 676 行，在 kivy.properties.StringProperty.check (kivyproperties.c:8613)ValueError: Image.source 只接受 str

解决方案

io.BytesIO()执行后，data为Bytes.使用 Kivy

REQUIREMENT

I'm trying to retrieve an image from Database and set this image to kivy image widget, this operation throws a ValueError, unsure of the cause. Welcome any inputs.

Database: Sqlite3

Table name: Users

Columns: UserID, UserName, UserImage

   def populate_fields(self): # NEW
      # Code retrieves text data and display in textinput fields here.

      # STEP 1: RETRIEVE IMAGE
      connection = sqlite3.connect("demo.db")
      with connection:
          cursor = connection.cursor()
          cursor.execute("SELECT UserImage from Users where 
          UserID=?",self.data_items[columns[0]]['text'] )
          image = cursor.fetchone()
          data = io.BytesIO(image[0])

      #STEP 2: SET OUTPUT TO IMAGE WIDGET
          self.image.source = data # ---> triggers an Error

ERROR TRACEBACK:

self.image.source = data
   File "kivyweakproxy.pyx", line 33, in kivy.weakproxy.WeakProxy.__setattr__ (kivyweakproxy.c:1471)
   File "kivyproperties.pyx", line 478, in kivy.properties.Property.__set__ (kivyproperties.c:5572)
   File "kivyproperties.pyx", line 513, in kivy.properties.Property.set (kivyproperties.c:6352)
   File "kivyproperties.pyx", line 504, in kivy.properties.Property.set (kivyproperties.c:6173)
   File "kivyproperties.pyx", line 676, in kivy.properties.StringProperty.check (kivyproperties.c:8613)
 ValueError: Image.source accept only str

解决方案

After execution of io.BytesIO(), data is in Bytes. Use Kivy CoreImage and texture to convert data.

Replace

self.image.source = data

with:

self.image.texture = CoreImage(data, ext="png").texture

Image source

source

Filename / source of your image.

source is a StringProperty and defaults to None

Output