I've a 4-page form, where in 3rd form i'm selecting an image for upload. I'm storing the contents of first 3 forms in session. after 4th form is submitted, i'm collecting the required data from session variables and saving them in database.
How do i destroy the session variables in django after 4th form is submitted because when i'm filling a new 4-page form, i get the previously uploaded image in 3rd form.
Is there any better way to execute multi-page forms in django?
You need to call del request.session['key'] to delete data from session. So try like this:
def fourth_form_submission(request):
form = FourthForm(request.POST)
if form.is_valid():
data = form.cleaned_data
# save data to DB from session
try:
del request.session['form_1_data']
del request.session['form_2_data']
del request.session['form_3_data']
except KeyError:
pass
return HttpResponse("Data has been saved.")
Or you can use flush(), but it will delete all session data.
More information can be found regarding this in documentation.
Related
what I needed is just an image was upload into uploads folder as example in web2py book.
Is this only possible with SQLForm ? or what wrong with my code.Here's my code.
model : db.py
db.define_table('image',
Field('title'),
Field('file', 'upload'),
format = '%(title)s')
in mysql image table was created title as varchar(70) file as mediumblob
controller
def index():
image_form = FORM(
INPUT(_name='image_title',_type='text'),
INPUT(_name='image_file',_class='upload',_type='file')
)
return locals()
view
{{extend "layout.html"}}
{{=form}}
I believe FORM can do everything SQLFORM can do except it requires a lot more effort. FORM simply creates a normal html form element. SQLFORM does that plus builds all the controls on the form and hooks up the Submit button.
I always try to use SQLFORM if I can.
Your code should show a form but it won't save anything to the database. That is because you are missing the crucial form.process commands. It is this command that does all the hard work of validating the form and adding or updating the record.
From the book and modified based on your code.
def index():
record = db.image(request.args(0)) # Tries to get an existing record where the id is specified in the first argument if the url.
image_form = SQLFORM(db.image, record) # Creates a form based on the 'image' table. If a record was found, it will show the record details
if image_form.process().accepted: # When the form is submitted (not when it is created) it will try and process it and add the record or save any changes to the record.
response.flash = 'form accepted'
elif image_form.errors:
response.flash = 'form has errors'
return dict(form=image_form)
A another problem is that you have called your form image_form in the controller but you are trying to display form in the view. My code above should work fine with your view - you can see that image_form is changed to form in the return command (form=image_form).
I have a basic view that retrieves some data, renders my page and sends some data to this page:
def myview(request)
one = values.objects.get(user=request.user).address
two = values.objects.get(user=request.user).number
return render(request, "main/mytemplate.html",
context={'address': one, 'numbers': two})
So the values retrieved by those two queries are shown on my page.
Now, on the same page, called mytemplate.html, i'm using another view, which is supposed to handle a form and some other operations:
def secondview(request):
if request.method == 'POST':
if 'button1' in request.POST:
form = MyForm(request.POST)
# check whether it's valid:
if form.is_valid():
profile = form.save(commit=False)
profile.user = request.user
profile.save()
return HttpResponseRedirect(request.path_info)
else:
form = MyForm()
return HttpResponse('it works!')
How can i use the data retrieved by those two queries in the second view? The queries are executed when the page is loaded by the first view. Then, in the same page the second view is used. I want to use the two variables one and two in the second view. Is there a way to do this in Django?
Why don't you make the same queries in the second view? Because i would like the second form to be as fast as possible in terms of reload, without having to do a DB query each time that view is used. Also, since i already retrieved those values when the page is opened, it would be a waste to do that again.
I don't know if this question is clear enough, but the core of it is: can i pass variables/data between two views in django?
You have few options:
Simplest way: include this data in request to the second view (as part of the form data, see an example below). You might even use a single view: if POST was send - store data else do request and show it on a page.
Use cache for that (see an example below) - But I'd recommend to use Django built-in package. Here is a basic example how to use it
Use Django Sessions (see an example below) - it is working option despite of that they have another purpose. When customer is loaded Django will load full session record, so you'll have all data in request.session variable. But that is bad practice: you can get a lot of data duplication and increased database memory consumption.
Use API (e.g. using DjangoRestFramework) together with usual Django app. So you'll just get data you need, and when you need. These API requests can also be cached so it is fast solution.
Yes, you can use session to pass data across views. A session works like a temporary server storage and keeps the needed data in a dictionary form.
For instance, add the following lines to myview:
request.session['one'] = one
request.session['two'] = two
Then, retrieve the data in secondview by referring to the session:
one = request.session['one']
two = request.session['two']
you can use cookies. but if you want more secure your request i suggest to you using redis and the python client for redis
file settings.py
redis = redis.Redis(host='localhost', port=6379, db=0)
file views.py
def view1(request):
redis.set("foo", "boo")
def view2(request):
boo = redis.get("foo")
Why not just saving the results of the two queries as hidden fields in the form rendered by the first template ?
<form ...>
<input type="hidden" id="address" name="address" value="{{address}}">
<input type="hidden" id="numbers" name="numbers" value="{{numbers}}">
...
Then, you can either add 'address' and 'numbers' form fields to MyForm
address = forms.CharField(widget=forms.HiddenInput(), required=False)
...
or just retrieve the values from request.POST
I'm new to both web development and django so maybe that's a noob question.
I want to do the following:
Ask user to fill some form and submit it.
Then, parse and format the content and display it back to the user to let him verify it.
User can accept the result or go back to the previous view, update data and resend.
This is as far as I can think:
views.py
def add_content(request):
if request.method == 'POST':
form = AddContentForm(request.POST)
if form.is_valid():
content = form.save(commit=False)
return verify_content(request, content)
else:
form = AddContentForm()
return render(request, 'myapp/add_content.html', {'form' : form})
def verify_content(request, content):
return render(request, 'myapp/verify_content.html', {'content' : content})
The verify_content template will obviously contain two buttons ('back', 'ok'), but I don't know how to pass the content object to a view for saving it in the db, or send it back to the previous view from there. Should I use js? Can i do it with just server side code?
Maybe my whole logic is wrong. Should I save the object in the db before verification and then delete it if needed (sounds ugly)? What is a good way to implement this?
Thanks in advance for your time.
You could use the users session for this:
request.session['content'] = content
and in the view where the user should verify his input do:
content = request.session['content']
and voilá you got the content between 2 views.
Django also secures that users can't tinker with its data by either saving it server side, or in a signed cookie.
I would save the form with commit=True in the add_content view, and would add a verified field or something to the model. Then you can append the pk as GET parameter to the link which will get you back to add_content view from verify. You can extract the parameter from request.GET dict.
When both the GET and POST methods are in the same handler class, and I want to populate form fields with user input after failed form validation, I do this...
Class CommentHandler(BaseHandler):
def get(self, form=None):
if form is None: # create new form unless populated form is passed in
form = CommentForm()
# query DB and create template context
self.render('page.html', **context)
def post(self):
form = CommentForm(self.request.POST)
if form.validate():
# populate entity with form data and save to DB
return self.redirect_to('page')
self.get(form=form) # pass populated form back to user for editing
I don't know if this is the best way to get form data back to the user, but it seems to work. My question is: how do I pass that data back into the form if the GET and POST methods are in different handler classes?
class PageHandler(BaseHandler):
def get(self):
# displays form to user
class CommentHandler(BaseHandler):
def post(self):
# processes POSTed form data...
# but if form.validate() fails,
# how can I pass the form data back to the user
# so they can edit their form input?
When you post and call validate() WTForms binds the form encoded data to the Form instance. An http POST can return a response just like a GET this is why you sometimes get those funny messages in your browser when a server application has failed validation and you try to refresh. Its because the refresh action is going to invoke the GET processing pipeline and you will lose your POST data.
What you need to do instead of delegating back to the get implementation you just need to render a response from your post implementation that passes Form instance with the data bound to it back in the response. If you have set your template up in the recommended way the data will automatically show up in the appropriate fields. Below is a snippet of what your Handler might look like.
def post(self):
form = CommentForm(self.request.POST)
if form.validate():
# populate entity with form data and save to DB
return self.redirect_to('page')
# If we are here it means we failed validation
# We need to send back the data the use supplied
# with error messages so we can re-render the form
# with their data and error messages indicating why
# it was rejected.
self.render('page.html', form=form) # pass populated form back to user for editing
This of course assumes that your page.html knows what to do with the Form instance.
Here's one workflow that may help to solve your problem. I chose to provide a workflow instead of a specific code snippet in order to avoid being too prescriptive in the technology you use to solve the problem.
GET
if session contains form data:
add form data from session to template context
display form
POST
if form validates:
clear this form data from session
save to db
else:
save form data to session
redirect to GET handler
How can I clean the data in a form and have the cleaned data redisplayed instead of the submitted data?
There are several fields in my form, and every time the user submits it, it should be redisplayed with the values the user entered. However, some of the fields I would like to clean and update for the user. More specifically, I have a field FriendlyIntegerField(forms.CharField) in which I override to_python to not only call int(str(value)), but also set any negative number to 0 etc. I do not want to redisplay the form with the invalid data and have the user fix it himself (which is how Django wants me to do it).
I don't have a problem cleaning the data and use it for the rest of my view-function, but how can I update the actual form with this data?
By the way, the form does not reflect a structure in my data model, and so inherits from Form, not ModelForm.
Edit:
My Field (in a stripped down version) looks like this:
class FriendlyIntegerField(forms.CharField):
def to_python(self, value):
try:
return str(int(str(value).replace(' ','')))
except:
raise forms.ValidationError('some error msg')
My Form (in a stripped down version) looks like this:
class SearchForm(forms.Form):
price_from = FriendlyIntegerField()
price_to = FriendlyIntegerField()
And my view:
def search(request, key):
if request.method == 'POST':
form = SearchForm(request.REQUEST)
if not form.is_valid():
print "Form not valid"
else:
form = SearchForm()
return render_to_response('path_to_template', {'form' : form}
If, after you've cleaned your form with is_valid(), you render that cleaned form with your view, rather than redirect to a new page, you'll see the cleaned data in your page.
(If you wanted the user to see this cleaned data and then properly submit it, you could use a hidden field to track whether the form data has already been cleaned, but this isn't without complications...)