TypedChoiceField - формы Django

Опубликовано: 24 Февраля, 2022

TypedChoiceField в Django Forms - это поле, подобное ChoiceField, для выбора определенного варианта из списка доступных вариантов. Он используется для реализации полей «Штат», «Страны» и т. Д., Например, для полей, информация для которых уже определена, и пользователь должен выбрать одно из них. Он используется для ввода текста от пользователя. Виджет по умолчанию для этого ввода - Select. Он нормализуется до: строки. Он используется для приведения значения к определенному типу данных.

TypedChoiceField имеет один дополнительный обязательный аргумент:

выбор:
Либо итерация из 2-х кортежей для использования в качестве выбора для этого поля, либо вызываемый объект, который возвращает такой итерируемый. Этот аргумент принимает те же форматы, что и аргумент choices для поля модели.

TypedChoiceField имеет два необязательных аргумента:

принуждение:
Функция, которая принимает один аргумент и возвращает принудительное значение. Примеры включают встроенные типы int, float, bool и другие. По умолчанию используется функция идентификации.
empty_value:
Значение, которое следует использовать для представления «пусто». По умолчанию используется пустая строка; Здесь нет другого распространенного выбора.

Синтаксис

 field_name = forms.TypedChoiceField (** параметры)

Форма Django TypedChoiceField Описание

Illustration of TypedChoiceField using an Example. Consider a project named geeksforgeeks having an app named geeks.

Refer to the following articles to check how to create a project and an app in Django.
How to Create a Basic Project using MVT in Django?
How to Create an App in Django ?

Enter the following code into forms.py file of geeks app.

from django import forms
  
# iterable
GEEKS_CHOICES = (
    (1, "A"),
    (2, "B"),
    (3, "C"),
    (4, "D"),
    (5, "E"),
)
  
# creating a form 
class GeeksForm(forms.Form):
    geeks_field = forms.TypedChoiceField(
                   choices = GEEKS_CHOICES,
                   coerce = str
                  )

Add the geeks app to INSTALLED_APPS

# Application definition
  
INSTALLED_APPS = [
    "django.contrib.admin",
    "django.contrib.auth",
    "django.contrib.contenttypes",
    "django.contrib.sessions",
    "django.contrib.messages",
    "django.contrib.staticfiles",
    "geeks",
]

Now to render this form into a view we need a view and a URL mapped to that URL. Let’s create a view first in views.py of geeks app,

from django.shortcuts import render
from .forms import GeeksForm
  
# Create your views here.
def home_view(request):
    context = {}
    context["form"] = GeeksForm()
    return render( request, "home.html", context)

Here we are importing that particular form from forms.py and creating an object of it in the view so that it can be rendered in a template.
Now, to initiate a Django form you need to create home.html where one would be designing the stuff as they like. Let’s create a form in home.html.

<form method = "GET">
    {{ form }}
    <input type = "submit" value = "Submit">
</form>

Finally, a URL to map to this view in urls.py

from django.urls import path
  
# importing views from views..py
from .views import home_view
  
urlpatterns = [
    path("", home_view ),
]

Let’s run the server and check what has actually happened, Run

Python manage.py runserver

Thus, an geeks_field TypedChoiceField is created by replacing “_” with ” “. It is a field to input choices of strings.

How to use TypedChoiceField ?

TypedChoiceField is used for input of small-sized strings in the database. One can input state, country, city, etc. Till now we have discussed how to implement TypedChoiceField but how to use it in the view for performing the logical part. To perform some logic we would need to get the value entered into field into a python string instance.
In views.py,

from django.shortcuts import render
from .forms import GeeksForm
  
# Create your views here.
def home_view(request):
    context ={}
    form = GeeksForm(request.GET or None)
    context["form"]= form
    if request.GET and form.is_valid():
        temp = form.cleaned_data.get("geeks_field")
        print(type(temp))
    return render(request, "home.html", context)

Now let’s try entering data into the field.

Now this data can be fetched using corresponding request dictionary. If method is GET, data would be available in request.GET and if post, request.POST correspondingly. we have used cleaned_data attribute of a form for fetching data from the view. In above example we have the value in temp which we can use for any purpose.

It shows the int variable 2 as a string class as the value is coerced by TypedChoiceField. This is the advantage of ChoiceField over TypedChoiceField.

Core Field Arguments

Core Field arguments are the arguments given to each field for applying some constraint or imparting a particular characteristic to a particular Field. For example, adding an argument required = False to TypedChoiceField will enable it to be left blank by the user. Each Field class constructor takes at least these arguments. Some Field classes take additional, field-specific arguments, but the following should always be accepted:

Field Options	Description
required	By default, each Field class assumes the value is required, so to make it not required you need to set `required=False`
label	The label argument lets you specify the “human-friendly” label for this field. This is used when the Field is displayed in a Form.
label_suffix	The label_suffix argument lets you override the form’s label_suffix on a per-field basis.
widget	The widget argument lets you specify a Widget class to use when rendering this Field. See Widgets for more information.
help_text	The help_text argument lets you specify descriptive text for this Field. If you provide help_text, it will be displayed next to the Field when the Field is rendered by one of the convenience Form methods.
error_messages	The error_messages argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override.
validators	The validators argument lets you provide a list of validation functions for this field.
localize	The localize argument enables the localization of form data input, as well as the rendered output.
disabled.	The disabled boolean argument, when set to True, disables a form field using the disabled HTML attribute so that it won’t be editable by users.

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TypedChoiceField - формы Django

Форма Django TypedChoiceField Описание

How to use TypedChoiceField ?

Core Field Arguments

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