CE419 Session 17: Forms Web Programming Forms <form> is the - - PowerPoint PPT Presentation

CE419 Web Programming

Session 17: Forms

Forms

• <form> is the way that allows users to send data to

server for processing.

2

Forms

3

Processing Forms

• It’s possible to process forms just using Django’s

HttpRequest class.

• request.GET, request.POST, request.FILES
• Ain't Nobody Got Time For That!

4

Processing Forms – The Stone Age Way

def register(request): if request.method == "POST": username = request.POST.get('username', None) if not username: username_error = u"ﺪﯿﻵﻨﮐ دﺪرﺮاﺎوﻮ اﺎرﺮ یﯽﺮﺑرﺮﺎﮐ مﻢﺎﻧ." elif not re.match("[\d\w_\.]{3,}", username): username_error = u"ﻞﻣﺎﺷ وﻮ ﺮﺘﮐاﺎرﺮﺎﮐ ﮫﻫﺳ ﻞﻗاﺎﺪﺣ ﺪﯾﻴﺎﺑ یﯽﺮﺑرﺮﺎﮐ مﻢﺎﻧ ﺪﺷﺎﺑ فﻒوﻮﺮﺣ وﻮ دﺪاﺎﺪﻋاﺎ." elif User.objects.filter(username=username).count() > 0: username_error = u"ﺖﺳاﺎ هﻪﺪﺷ ﮫﻫﺘﻓﺮﮔ ﻼﺒﻗ یﯽﺮﺑرﺮﺎﮐ مﻢﺎﻧ ﻦﯾﻴاﺎ." email = request.POST.get('email', None) if not email: email_error = u"ﺪﯿﻵﻨﮐ دﺪرﺮاﺎوﻮ اﺎرﺮ ﻞﯿﻵﻤﯾﻴاﺎ سﺲرﺮدﺪآﺂ." elif not email_re.search(email): email_error = u"ﺪﯿﻵﻨﮐ دﺪرﺮاﺎوﻮ اﺎرﺮ یﯽﺮﺒﺘﻌﻣ ﻞﯿﻵﻤﯾﻴاﺎ." elif User.objects.filter(email=email).count() > 0: email_error = u"ﺖﺳاﺎ هﻪﺪﺷ هﻪدﺪﺎﻔﺘﺳاﺎ ﻼﺒﻗ ﻞﯿﻵﻤﯾﻴاﺎ سﺲرﺮدﺪآﺂ ﻦﯾﻴاﺎ."

5

Default value in the case that ‘username’ doesn’t exist.

Processing Forms – The Stone Age Way

• Pretty cool, huh?
• Don’t Repeat Yourself, dude.

6

Django Forms API

• Helps you with some common tasks:
• Auto-generate an HTML form for you,
• Check submitted data against set of validation rules,
• Redisplay form in case of errors,
• Convert submitted data to relevant Python types.

7

Form Object

• A Form object encapsulates a sequence of form fields

and a collection of validation rules.

from django import forms class ContactForm(forms.Form): subject = forms.CharField(max_length=100) message = forms.CharField() sender = forms.EmailField() cc_myself = forms.BooleanField(required=False)

CharField DateField FileField EmailField BooleanField RegexField … forms.py

9

Field Object

• Important field arguments:
• Field.required
• Field.label
• Field.initial
• Field.widget
• Field.help_text
• Field.error_messages
• Field.validators

father_name = forms.CharField(required=False) url = forms.URLField(label='Your Web site') url = forms.URLField(initial='http://') comment = forms.CharField(widget=forms.Textarea)

Not for fallback.

sender = forms.EmailField(help_text='Real address.') name = forms.CharField(error_messages={'required': ‘Enter your name, dude.’}) even_field = forms.IntegerField(validators=[validate_even])

10

Using a Form in a View

from django.shortcuts import render from django.http import HttpResponseRedirect from mysite.forms import ContactForm def contact(request): if request.method == 'POST': form = ContactForm(request.POST) if form.is_valid(): # processing the form and doing something return HttpResponseRedirect('/thanks/') else: form = ContactForm() return render(request, 'contact.html', {'form': form,})

There are three different code paths here.

Bound vs. Unbound

The successfully validated form data will be in the form.cleaned_data dictionary.

11

Processing the Form

if form.is_valid(): subject = form.cleaned_data['subject'] message = form.cleaned_data['message'] sender = form.cleaned_data['sender'] cc_myself = form.cleaned_data['cc_myself'] recipients = ['info@example.com'] if cc_myself: recipients.append(sender) from django.core.mail import send_mail send_mail(subject, message, sender, recipients) return HttpResponseRedirect('/thanks/')

You can still access the unvalidated data directly from request.POST.

12

Displaying the Form

<form action="/contact/" method="post">{% csrf_token %} {{ form.as_p }} <input type="submit" value="Submit" /> </form>

Don’t panic. We’ll talk about this in a later session. Only outputs form fields, don’t forget <form></form>.

Render result: <form action="/contact/" method="post"> <p><label for="id_subject">Subject:</label> <input id="id_subject" type="text" name="subject" maxlength="100" /></p> <p><label for="id_message">Message:</label> <input type="text" name="message" id="id_message" /></p> <p><label for="id_sender">Sender:</label> <input type="email" name="sender" id="id_sender" /></p> <p><label for="id_cc_myself">Cc myself:</label> <input type="checkbox" name="cc_myself" id="id_cc_myself" /></p> <input type="submit" value="Submit" /> </form>

13

Don’t Like It? Okay, whatever.

<form action="/contact/" method="post"> {{ form.non_field_errors }} <div class="fieldWrapper"> {{ form.subject.errors }} <label for="id_subject">Email subject:</label> {{ form.subject }} </div> <div class="fieldWrapper"> {{ form.message.errors }} <label for="id_message">Your message:</label> {{ form.message }} </div> <div class="fieldWrapper"> {{ form.sender.errors }} <label for="id_sender">Your email address:</label> {{ form.sender }} </div> <div class="fieldWrapper"> {{ form.cc_myself.errors }} <label for="id_cc_myself">CC yourself?</label> {{ form.cc_myself }} </div> <p><input type="submit" value="Send message" /></p> </form> Displays a list of form errors, rendered as an unordered list. Produces the HTML needed to display the form widget.

14

We’ll talk about it in a minute. Be patience.

More Convenient Way

<form action="/contact/" method="post"> {% for field in form %} <div class="fieldWrapper"> {{ field.errors }} {{ field.label_tag }} {{ field }} </div> {% endfor %} <p><input type="submit" value="Send message" /></p> </form>

{{ field.label }} {{ field.value }} {{ field.help_text }} {{ field.is_hidden }} {{ field.field }} {{ field.html_name }} ...

15

Using Forms Directly with a Model

• Don’t Repeat Yourself

class Author(models.Model): name = models.CharField(max_length=100) title = models.CharField(max_length=3, choices=TITLE_CHOICES) birth_date = models.DateField(blank=True, null=True) def __str__(self): return self.name class Book(models.Model): name = models.CharField(max_length=100) authors = models.ManyToManyField(Author) class AuthorForm(forms.ModelForm): class Meta: model = Author fields = ['name', 'title', 'birth_date'] class BookForm(forms.ModelForm): class Meta: model = Book fields = ['name', 'authors']

ModelForm objects have an extra .save() method.

16

Any Questions?

26

References

• https://docs.djangoproject.com/en/1.6/topics/forms/
• https://docs.djangoproject.com/en/1.6/ref/forms/fields/
• https://docs.djangoproject.com/en/1.6/ref/forms/

widgets/

• https://docs.djangoproject.com/en/1.6/ref/forms/

validation/

• http://www.python.org

27