Why does the render_template keep on showing the old value of the flask form? - flask

Question

I've been searching for an answer for hours. I apologise if I missed something.
I'm using the same form multiple times in order to add rows to my database.
Every time I check an excel file to pre-fill some of the wtforms StringFields with known information that the user may want to change.
The thing is: I change the form.whatever.data and when printing it, it shows the new value. But when I render the template it keeps showing the old value.
I tried to do form.hours_estimate.data = "" before assigning it a new value just in case but it didn't work.
I will attach here the route I'm talking about. The important bit is after # Get form ready for next service. If there's more info needed please let me know.
Thank you very much.
#coordinator_bp.route("/coordinator/generate-order/<string:pev>", methods=['GET', 'POST'])
#login_required
def generate_order_services(pev):
if not (current_user.is_coordinator or current_user.is_manager):
return redirect(url_for('public.home'))
# Get the excel URL
f = open("./app/database/datafile", 'r')
filepath = f.read()
f.close()
error = None
if GenerateServicesForm().submit1.data and GenerateServicesForm().validate():
# First screen submit (validate the data -> first Service introduction)
form = FillServiceForm()
next_service_row = get_next_service_row(filepath)
if next_service_row is None:
excel_info = excel_get_pev(filepath)
error = "Excel error. Service code not found. If you get this error please report the exact way you did it."
return render_template('coordinator/get_pev_form.html', form=GetPevForm(), error=error, info=excel_info)
service_info = get_service_info(filepath, next_service_row)
service_code = service_info[0]
start_date = service_info[1]
time_estimate = service_info[2]
objects = AssemblyType.get_all()
assembly_types = []
for assembly_type in objects:
assembly_types.append(assembly_type.type)
form.service_code.data = service_code
form.start_date.data = start_date
form.hours_estimate.data = time_estimate
return render_template('coordinator/fill_service_form.html', form=form, error=error, assembly_types=assembly_types)
if FillServiceForm().submit2.data:
if not FillServiceForm().validate():
objects = AssemblyType.get_all()
assembly_types = []
for assembly_type in objects:
assembly_types.append(assembly_type.type)
return render_template('coordinator/fill_service_form.html', form=FillServiceForm(), error=error,
assembly_types=assembly_types)
# Service screen submits
# Here we save the data of the last submit and ready the next one or end the generation process
# Ready the form
form = FillServiceForm()
next_service_row = get_next_service_row(filepath)
if next_service_row is None:
excel_info = excel_get_pev(filepath)
error = "Excel error. Service code not found. If you get this error please report the exact way you did it."
return render_template('coordinator/get_pev_form.html', form=GetPevForm(), error=error, info=excel_info)
service_info = get_service_info(filepath, next_service_row)
service_code = service_info[0]
form.service_code.data = service_code
# create the service (this deletes the service code from the excel)
service = create_service(form, filepath)
if isinstance(service,str):
return render_template('coordinator/fill_service_form.html', form=form, error=service)
# Get next service
next_service_row = get_next_service_row(filepath)
if next_service_row is None:
# This means there is no more services pending
return "ALL DONE"
else:
# Get form ready for next service
service_info = get_service_info(filepath, next_service_row)
service_code = service_info[0]
start_date = service_info[1]
time_estimate = service_info[2]
print("time_estimate")
print(time_estimate) # I get the new value.
objects = AssemblyType.get_all()
assembly_types = []
for assembly_type in objects:
assembly_types.append(assembly_type.type)
form.service_code.data = service_code
form.start_date.data = start_date
form.hours_estimate.data = time_estimate
print(form.hours_estimate.data) # Here I get the new value. Everything should be fine.
# In the html, the old value keeps on popping.
return render_template('coordinator/fill_service_form.html', form=form, error=error,
assembly_types=assembly_types)
number_of_services = excel_get_services(filepath=filepath, selected_pev=pev)
# Get the number of the first excel row of the selected pev
first_row = excel_get_row(filepath, pev)
if first_row is None:
excel_info = excel_get_pev(filepath)
error = "Excel error. PEV not found. If you get this error please report the exact way you did it."
return render_template('coordinator/get_pev_form.html', form=GetPevForm(), error=error, info=excel_info)
service_code = []
start_date = []
time_estimate_code = []
quantity = []
# Open the excel
wb = load_workbook(filepath)
# grab the active worksheet
ws = wb.active
for idx in range(number_of_services):
# Append the data to the lists
service_code.append(ws.cell(row=first_row+idx, column=12).value)
start_date.append(str(ws.cell(row=first_row + idx, column=5).value)[:10])
time_estimate_code.append(ws.cell(row=first_row+idx, column=7).value)
quantity.append(ws.cell(row=first_row + idx, column=9).value)
wb.close()
return render_template('coordinator/generate_services_form.html',
form=GenerateServicesForm(),
pev=pev,
service_code=service_code,
start_date=start_date,
time_estimate_code=time_estimate_code,
quantity=quantity)

Answer 1

Well I found a workarround: I send the data outside the form like this:
return render_template('coordinator/fill_service_form.html', form=form, error=error,
assembly_types=assembly_types,
service_code=service_code,
start_date=start_date,
time_estimate=time_estimate)
And replace the jinja form for this:
<input class="form-control" placeholder="2021-04-23" name="start_date" type="text" value="{{start_date}}">
I'm still using the form (name= the form field name) and at the same time I input the value externally.
I hope this helps somebody.