web programming session 17: forms -...

CE419 Web Programming Session 17 Forms

Forms

bull ltformgt is the way that allows users to send data to server for processing

2

Forms

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Processing Forms

bull Itrsquos possible to process forms just using Djangorsquos HttpRequest class

bull requestGET requestPOST requestFILES

bull Aint Nobody Got Time For That

4

Processing Forms ndash The Stone Age Way

def register(request) if requestmethod == POST username = requestPOSTget(username None) if not username username_error = uنامم کارربریی رراا وواارردد کنيید elif not rematch([dw_]3 username) username_error = uنامم کارربریی بايید حدااقل سهھ کاررااکتر وو شامل ااعداادد وو حرووفف باشد elif Userobjectsfilter(username=username)count() gt 0 username_error = uاايین نامم کارربریی قبال گرفتهھ شدهه ااست email = requestPOSTget(email None) if not email email_error = uآآددررسس اايیميیل رراا وواارردد کنيید elif not email_research(email) email_error = uاايیميیل معتبریی رراا وواارردد کنيید elif Userobjectsfilter(email=email)count() gt 0 email_error = uاايین آآددررسس اايیميیل قبال ااستفاددهه شدهه ااست

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Default value in the case that lsquousernamersquo doesnrsquot exist

Processing Forms ndash The Stone Age Way

bull Pretty cool huh

bull Donrsquot Repeat Yourself dude

6

Django Forms API

bull Helps you with some common tasks

bull Auto-generate an HTML form for you

bull Check submitted data against set of validation rules

bull Redisplay form in case of errors

bull Convert submitted data to relevant Python types

7

Form Object

bull A Form object encapsulates a sequence of form fields and a collection of validation rules

from django import forms

class ContactForm(formsForm) subject = formsCharField(max_length=100) message = formsCharField() sender = formsEmailField() cc_myself = formsBooleanField(required=False)

CharField DateField FileField

EmailField BooleanField RegexField

hellip

formspy

9

Field Object

bull Important field arguments bull Fieldrequired bull Fieldlabel bull Fieldinitial bull Fieldwidget bull Fieldhelp_text bull Fielderror_messages

bull Fieldvalidators

father_name = formsCharField(required=False)

url = formsURLField(label=Your Web site)

url = formsURLField(initial=http)

comment = formsCharField(widget=formsTextarea)

Not for fallback

sender = formsEmailField(help_text=Real address)

name = formsCharField(error_messages=required lsquoEnter your name dudersquo)

even_field = formsIntegerField(validators=[validate_even])

10

Using a Form in a View

from djangoshortcuts import renderfrom djangohttp import HttpResponseRedirectfrom mysiteforms import ContactForm

def contact(request) if requestmethod == POST form = ContactForm(requestPOST) if formis_valid() processing the form and doing something return HttpResponseRedirect(thanks) else form = ContactForm()

return render(request contacthtml form form)

There are three different code paths here

Bound vs Unbound

The successfully validated form data will be in the formcleaned_data

dictionary

11

Processing the Form

if formis_valid() subject = formcleaned_data[subject] message = formcleaned_data[message] sender = formcleaned_data[sender] cc_myself = formcleaned_data[cc_myself]

recipients = [infoexamplecom] if cc_myself recipientsappend(sender)

from djangocoremail import send_mail send_mail(subject message sender recipients) return HttpResponseRedirect(thanks)

You can still access the unvalidated data

directly from requestPOST

12

Displaying the Form

ltform action=contact method=postgt csrf_token formas_p ltinput type=submit value=Submit gtltformgt

Donrsquot panic Wersquoll talk about this in a later session

Only outputs form fields donrsquot forget ltformgtltformgt

Render result ltform action=contact method=postgtltpgtltlabel for=id_subjectgtSubjectltlabelgt ltinput id=id_subject type=text name=subject maxlength=100 gtltpgtltpgtltlabel for=id_messagegtMessageltlabelgt ltinput type=text name=message id=id_message gtltpgtltpgtltlabel for=id_sendergtSenderltlabelgt ltinput type=email name=sender id=id_sender gtltpgtltpgtltlabel for=id_cc_myselfgtCc myselfltlabelgt ltinput type=checkbox name=cc_myself id=id_cc_myself gtltpgtltinput type=submit value=Submit gtltformgt

13

Donrsquot Like It Okay whatever

ltform action=contact method=postgt formnon_field_errors ltdiv class=fieldWrappergt formsubjecterrors ltlabel for=id_subjectgtEmail subjectltlabelgt formsubject ltdivgt ltdiv class=fieldWrappergt formmessageerrors ltlabel for=id_messagegtYour messageltlabelgt formmessage ltdivgt ltdiv class=fieldWrappergt formsendererrors ltlabel for=id_sendergtYour email addressltlabelgt formsender ltdivgt ltdiv class=fieldWrappergt formcc_myselferrors ltlabel for=id_cc_myselfgtCC yourselfltlabelgt formcc_myself ltdivgt ltpgtltinput type=submit value=Send message gtltpgtltformgt

Displays a list of form errors rendered as an unordered list

Produces the HTML needed to display the form widget

14

Wersquoll talk about it in a minute Be patience

More Convenient Way

ltform action=contact method=postgt for field in form ltdiv class=fieldWrappergt fielderrors fieldlabel_tag field ltdivgt endfor ltpgtltinput type=submit value=Send message gtltpgtltformgt

fieldlabel fieldvalue fieldhelp_text fieldis_hidden fieldfield fieldhtml_name

15

Using Forms Directly with a Model

bull Donrsquot Repeat Yourself

class Author(modelsModel) name = modelsCharField(max_length=100) title = modelsCharField(max_length=3 choices=TITLE_CHOICES) birth_date = modelsDateField(blank=True null=True)

def __str__(self) return selfname

class Book(modelsModel) name = modelsCharField(max_length=100) authors = modelsManyToManyField(Author)

class AuthorForm(formsModelForm) class Meta model = Author fields = [name title birth_date]

class BookForm(formsModelForm) class Meta model = Book fields = [name authors]

ModelForm objects have an extra save() method

16

Any Questions

26

References

bull httpsdocsdjangoprojectcomen16topicsforms

bull httpsdocsdjangoprojectcomen16refformsfields

bull httpsdocsdjangoprojectcomen16refformswidgets

bull httpsdocsdjangoprojectcomen16refformsvalidation

bull httpwwwpythonorg

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