Forms

• https://docs.djangoproject.com/en/stable/topics/forms/

• https://docs.djangoproject.com/en/stable/ref/forms/api/

A basic form

from django import forms

class ContactForm(forms.Form):
    subject = forms.CharField(max_length=100)

Processing a form in a view function

def contact(request):
    if request.method == 'POST': # If the form has been submitted...
        form = ContactForm(request.POST) # A form bound to the POST data
        if form.is_valid(): # All validation rules pass
            # Process the data in form.cleaned_data
            # ...
            return HttpResponseRedirect('/thanks/') # Redirect after POST
    else:
        form = ContactForm() # An unbound form

    return render_to_response('contact.html', {
        'form': form,
    })

https://docs.djangoproject.com/en/stable/topics/forms/modelforms/

A model form

from django.forms import ModelForm, ValidationError

# Create the form class.
class ArticleForm(ModelForm):
    class Meta:
        model = Article
        fields = ('name', 'title')
        # or
        exclude = ('birth_date')

    def clean_fieldname(self):
        if 'fieldname' in self.cleaned_data:
            data = self.cleaned_data['fieldname']
            if not /valid/:
                raise ValidationError("msg")
            return data

    def clean(self):
        data = self.cleaned_data
        if not /valid/:
            raise ValidationError("msg")
        return data

# Creating a form to add an article.
form = ArticleForm()
...
new_article = form.save()

# Creating a form to change an existing article.
article = Article.objects.get(pk=1)
form = ArticleForm(instance=article)
...
form.save()

# Create a form to edit an existing Article, but use POST data to populate the form.
a = Article.objects.get(pk=1)
f = ArticleForm(request.POST, instance=a)
f.save()

Render form in template

<!-- Using table - avoid that part - but this does show how to render the fields individually -->
      <form {% if form.is_multipart %}enctype="multipart/form-data"{% endif %} action="" method="post" class="uniForm">{% csrf_token %}
        <table>
          <fieldset>
            {% if form.non_field_errors %}
              <tr><td colspan="2">{{ form.non_field_errors }}</td></tr>
            {% endif %}
            {% for field in form %}
              <tr{% if field.field.required %} class="required"{% endif %}>
                <th style="text-align: left"><label for="{{ field.id_for_label }}">{{ field.label }}:</label></th>
                <td>{% if field.errors %}
                      {{ field.errors }}<br/>
                    {% endif %}

                    {{ field }}

                    or even

                    <input id="{{ field.id_for_label }}"
                     name="{{ field.html_name }}"
                     value="{{ field.value }}"
                    {% if field.field.max_length != None %}
                        maxlength="{{ field.field.max_length }}"
                    {% endif %}
                    {% if field.field.min_length != None %}
                        minlength="{{ field.field.min_length }}"
                    {% endif %}
                     >
                    {% if field.help_text %}
                     <br/><span class="helptext">{{ field.help_text }}</span>
                     {% endif %}
                </td>
              </tr>
            {% endfor %}
          </fieldset>
        </table>
        <div class="ctrlHolder buttonHolder">
          <button type="submit" class="primaryAction" name="submit_changes">Submit changes</button>
        </div>
      </form>

<!-- Using a list, which is preferred -->

    <form {% if form.is_multipart %}enctype="multipart/form-data"{% endif %} action="" method="post" class="uniForm">{% csrf_token %}
        <fieldset>
            <ul>
                {{ form.as_ul }}
                <li>
                    <div class="ctrlHolder buttonHolder">
                        <button type="submit" class="primaryAction" name="submit_changes">Submit changes</button>
                    </div>
                </li>
            </ul>
        </fieldset>
    </form>

Read-only form

Call this on the form:

def make_form_readonly(form):
    """
    Set some attributes on a form's fields that, IN COMBINATION WITH TEMPLATE CHANGES,
    allow us to display it as read-only.
    """

    # Note that a new BoundField is constructed on the fly when you access
    # form[name], so any data we want to persist long enough for the template
    # to access needs to be on the "real" field.  We just use the BoundField
    # to get at the field value.

    for name in form.fields:
        field = form.fields[name]
        bound_field = form[name]
        if hasattr(field.widget, 'choices'):
            try:
                display_value = dict(field.widget.choices)[bound_field.value()]
            except KeyError:
                display_value = ''
        else:
            display_value = bound_field.value()

        field.readonly = True
        field.display_value = display_value

Do things like this in the templates:

{# Date field #}
{% if field.field.readonly %}
    <span class="form-control">{{ field.value|date:'c' }}</span>
{% else %}
    <input type="date" class="form-control" id="{{ field.id_for_label }}" name="{{ field.html_name }}" value="{{ field.value|date:'c' }}">
{% endif %}

{# input fields #}
{% if field.field.readonly %}
    <span class="form-control">{{ field.value }}</span>
{% else %}
    <input type="{% block input_field_type %}text{% endblock %}" class="form-control" id="{{ field.id_for_label }}" name="{{ field.html_name }}" value="{{ field.value }}" {% if field.field.widget.attrs.placeholder %}placeholder="{{ field.field.widget.attrs.placeholder }}"{% endif %} {% block input_attrs %}{% endblock %}>
{% endif %}

{# select fields #}
{% if field.field.readonly %}
    <span class="form-control">{{ field.field.display_value }}</span>
{% else %}
    <select class="form-control" id="{{ field.id_for_label }}"  name="{{ field.html_name }}" placeholder="">
      {% for val, label in field.field.widget.choices %}
        <option value="{{ val }}"{% if field.value|stringformat:'s' == val|stringformat:'s' %} selected{% endif %}>{{ label }}</option>
      {% endfor %}
    </select>
{% endif %}

Upload files

Template:

<form action="{% url 'links:import_bookmarks' %}" enctype="multipart/form-data" method="post">
  {% csrf_token %}
  {{ form }}
  <button class="btn btn-primary" type="submit">Import file</button>
</form>

Form class:

class ImportForm(forms.Form):
    file = forms.FileField()

View:

@login_required
def import_view(request):
    if request.method == "POST":
        form = ImportForm(request.POST, request.FILES)
        if form.is_valid():
            handle_uploaded_import(request, request.FILES["file"])
            return redirect("links:bookmarks")
        messages.error(request, "Form not valid")
    else:
        form = ImportForm()
    return render(request, "import.html", {"form": form})

def handle_uploaded_import(request, file):
    messages.info(request, "importing pages & sections")
    with transaction.atomic():
        data = json.load(file)
        # ...