jinja2.exceptions.UndefinedError: 'predictions' is undefined - flask

Question

I have a flask website. I was to make prediction images using the model that I build in Google Collab. In this, I have 25 classes and I took 3 classes for testing its work or not. I have already run it but when I go to the predict pages it seems to get the error 'jinja2.exceptions.UndefinedError: 'predictions' is undefined' Can anyone help me. Thank u
The Python Code:
with open('CNN.pth','rb') as file:
model=torch.load('CNN.pth',map_location='cpu')
classes=['00','01','02','03','04','05','06','07','08','09','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24']
def predict(filename,model):
img=load_img(filename,target_size=(32,32))
img=img_to_array(img)
img=img.reshape(1,32,32,3)
img = img.astype('float32')
img = img/255.0
result = model.predict(img)
dict_result = {}
for i in range(25):
dict_result[result[0][i]] = classes[i]
res = result[0]
res.sort()
res = res[::-1]
prob = res[:3]
prob_result = []
class_result = []
for i in range(3):
prob_result.append((prob[i]*100).round(2))
class_result.append(dict_result[prob[i]])
return class_result , prob_result
#app.route('/predict' , methods = ['GET' , 'POST'])
def success():
error = ''
target_img = os.path.join(os.getcwd() , 'static/images')
if request.method == 'POST':
if (request.files):
file = request.files['file']
if file and allowed_file(file.filename):
file.save(os.path.join(target_img , file.filename))
img_path = os.path.join(target_img , file.filename)
img = file.filename
class_result , prob_result = predict(img_path , model)
predictions = {
"class1":class_result[0],
"class2":class_result[1],
"class3":class_result[2],
"prob1": prob_result[0],
"prob2": prob_result[1],
"prob3": prob_result[2],
}
else:
error = "Please upload images of jpg , jpeg and png extension only"
if(len(error) == 0):
return render_template('predict.html' , img = img , predictions = predictions)
else:
return render_template('home.html' , error = error)
else:
return render_template('home.html')
Index.html
<tr>
<th>Class</th>
<th>Probability</th>
</tr>
<tr>
<th>{{predictions.class1}}</th>
<th>{{predictions.prob1}}</th>
</tr>
<tr>
<th>{{predictions.class2}}</th>
<th>{{predictions.prob2}}</th>
</tr>
<tr>
<th>{{predictions.class3}}</th>
<th>{{predictions.prob3}}</th>
</tr>

Answer 1

You have put an if - else condition, if you pay attention, the values ​​rendered in the if block and the rendered values ​​in the else block are different.
But all the values ​​are used in the html file.
If your code run else block so:
else:
return render_template('home.html' , error = error)
-> Where is the "prediction" value?
How can html predict a value that is not rendered as a value?
If you want to use like that:
#app.route('/predict' , methods = ['GET' , 'POST'])
def success():
predictions = dict() # if predictions is not empty ok, else doens't matter
error = ''
target_img = os.path.join(os.getcwd() , 'static/images')
if request.method == 'POST':
if (request.files):
file = request.files['file']
if file and allowed_file(file.filename):
file.save(os.path.join(target_img , file.filename))
img_path = os.path.join(target_img , file.filename)
img = file.filename
class_result , prob_result = predict(img_path , model)
predictions = {
"class1":class_result[0],
"class2":class_result[1],
"class3":class_result[2],
"prob1": prob_result[0],
"prob2": prob_result[1],
"prob3": prob_result[2],
}
else:
error = "Please upload images of jpg , jpeg and png extension only"
if(len(error) == 0):
return render_template('predict.html' , img = img , predictions = predictions)
else:
return render_template('home.html' , error = error, predictions = predictions)
else:
return render_template('home.html', predictions = predictions)
And you can use jinja condition like that:
{% if predictions|length > 0 %}
<tr>
<th>Class</th>
<th>Probability</th>
</tr>
<tr>
<th>{{predictions.class1}}</th>
<th>{{predictions.prob1}}</th>
</tr>
<tr>
<th>{{predictions.class2}}</th>
<th>{{predictions.prob2}}</th>
</tr>
<tr>
<th>{{predictions.class3}}</th>
<th>{{predictions.prob3}}</th>
</tr>
{% endif %}

Answer 2

in the last line of code written in python
return render_template('home.html')
you don't specify the predictions variable, unlike you did previously
return render_template('predict.html' , img = img , predictions = predictions)