local variable referenced before assignment django error

Question

This is my view.py and when i have a form which when i submit with the required fields it gives an appropriate output but when i don't input anything in the form and click submit i get an error saying "local variable 'researcher' referenced before assignment".

Also i want to know how do i keep my form data saved on the destination page

def about_experiment(request,ex_link_name):

    if request.method == 'POST':
        form = AboutHelp(request.POST)
        if form.is_valid():
            researcher = form.cleaned_data['researcher']
            study = form.cleaned_data['study']

    else:
        form = AboutHelp()
    return render(request, 'about_experiment.html', {'researcher': researcher, 'study': study})

my form on the source page is

<form action="{% url 'lazer.views.about_experiment' exp.link_name %}" method="POST" name="form"> 
  {% csrf_token %}
      <label>Researcher Name(s):<input type="text" name="researcher">
    <lable>Study Summary<textarea rows="10" cols="50" placeholder="here you go" maxlength="500" class="form-control" name="study"></textarea>
      <br>
      <input type = "submit" value="Submit" class="btn btn-primary" />
  </form>

My destination page where the form outputs are present

<h4> Name : {{ researcher }} </h4><br>
<h4> Summary : {{ study }} </h4>

Solution 1

in else part of views.py you mentioned researcher variable in render method that is producing this error.

so please add

researcher = None

before if statement

and also add

study = None

that will also create same error

forms.py

from django import forms
from .models import AboutHelp

    class AboutHelpForm(forms.ModelForm):
        class Meta:
            model = AboutHelp
            fields = '__all__'

views.py

def about_experiment(request,ex_link_name):
    researcher = None 
    study = None
    form = AboutHelpForm(request.POST or None)
    if request.method == 'POST':
        if form.is_valid():
            form.save()
    return render(request, 'about_experiment.html', {'researcher': researcher, 'study': study})

Solution 2

researcher and study are not assignment if request method is not POST and form is not valid. You should define this variable before if statement:

def about_experiment(request,ex_link_name):
    researcher = ''
    study = ''
    if request.method == 'POST':
    ...  

Comments

[unknown]

That worked well. Thanks. Also how do I save the Form data on the destination page permanently?

[unknown]

But when i am just filling the researcher text box in the form and keeping the study summary box empty and when i submit the form, its giving me none and none in both. How do i handle that exception.

[Neeraj Kumar]

According to your code you did not save form data into table. So firstly use form.save() method at last of form.is_valid() method.

[unknown]

I had already tried that but it gives me an error 'AboutHelp' object has no attribute 'save'

[Neeraj Kumar]

what is AboutHelp type. it should be type of form class not model class.

[unknown]

this is my forms.py class AboutHelp(forms.Form): researcher = forms.CharField(max_length=100) study = forms.CharField(max_length=500)

[Neeraj Kumar]

you are using simple Form not Modelform, So if you will use Modelform then that save() method will work and according to your simple form you have to pass both var to model class for save like : AboutHelp.objects.create(researcher=researcher, study=study) and read full documentation of django forms

[unknown]

could you help me write the code for modelform if possible

[unknown]

after i submit the form its giving an error no such table

[Neeraj Kumar]

Because you did not migrate django model So run this command: python manage.py migrate . you should follow django tutorials from starting.

[unknown]

Still it is not saving on the destination page the values for future reference. If i redirect again to that page its giving fields as None only.

[neverwalkaloner]

@unknown try to use request.session stackoverflow.com/questions/32787838/…