如何在Flask中加载上传的图像？

Question

我是Flask的新手并尝试加载上传到我服务器中的图片 但是当我尝试加载图片时，我总是得到broken link image 我认为我的代码中有一些错误，但我无法弄清楚它是什么......

Upload.py

import os
from flask import Flask, request, redirect, url_for, send_from_directory, 
              render_template
from app.forms import image_upload
from app.models import Upload_test

app = Flask(__name__)
APP_ROOT = os.path.dirname(os.path.abspath(__file__))
UPLOAD_FOLDER = os.path.join(APP_ROOT, 'files/')
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER

@app.route('/upload_test', methods=['GET','POST'])
def upload_test():
    form = image_upload()
    user_id = session['user_id'] 

    if request.method == 'POST':
       if form.validate_on_submit():     
          ext = (form.upload.data.filename).rsplit('.', 1)[1]
          filename = secure_filename(form.upload.data.filename + '_' + unicode(uuid.uuid4()) + "." + ext)
          file_path = os.path.join(app.config['UPLOAD_FOLDER'], filename)
          form.upload.data.save(file_path)

          image = Upload_test()

          image.user_id = user_id
          image.filename = filename        

          db.session.add(image)
          db.session.commit()

          return redirect(url_for('index', form=form, filename=filename, active_tab='index'))
       return render_template("upload_test.html", form=form, active_tab='upload_test')

Upload.py完美无缺

Load.py

import os
from flask import Flask, request, redirect, url_for, send_from_directory, 
              render_template
from app.models import Upload_test

@app.route('/upload_test', methods=['GET'])
def upload_test():
    if 'logged_in' in session:
       user_id = session['user_id']
       user = User.query.filter_by(id=user_id).first()
       user_image = show_image(user)
       return render_template('upload_test.html', user=user, user_image=user_image, active_tab='upload_test')
    else:
       return redirect(url_for('index'))

def show_image(user):
    user_image = db.session.query(Upload_test).filter(Upload_test.user_id == user.id).first()
    filename = user_image.filename
    return send_from_directory(app.config['UPLOAD_FOLDER'], filename)

这是 upload_test.html

的一部分

{% if user_image %}
<img src = '{{url_for('upload_test', filename=filname)}}'>
{% endif %}

我认为我在Load.py或upload_test.html（或两者兼有）中犯了错误 我哪里错了，如何正确显示图像？