# dokumentasi Django 2.0.8

# Kerangka pesan

Quite commonly in web applications, you need to display a one-time notification message (also known as "flash message") to the user after processing a form or some other types of user input.

For this, Django provides full support for cookie- and session-based messaging, for both anonymous and authenticated users. The messages framework allows you to temporarily store messages in one request and retrieve them for display in a subsequent request (usually the next one). Every message is tagged with a specific `level` that determines its priority (e.g., `info`, `warning`, or `error`).

## Mengadakan pesan

Messages are implemented through a middleware class and corresponding context processor.

Awalan `settings.py` dibuat oleh `django-admin startproject` sudah mengandung semua pengaturan dibutuhkan untuk mengadakan pesan fungsionalitas:

- `'django.contrib.messages'` di `INSTALLED_APPS`.

- `MIDDLEWARE` mengandung `'django.contrib.sessions.middleware.SessionMiddleware'` dan `'django.contrib.messages.middleware.MessageMiddleware'`.

  The default storage backend relies on sessions. That's why `SessionMiddleware` must be enabled and appear before `MessageMiddleware` in `MIDDLEWARE`.

- Pilihan `'context_processors'` dari backend `DjangoTemplates` ditentukan di pengaturan `TEMPLATES` anda mengandung `'django.contrib.messages.context_processors.messages'`.

If you don't want to use messages, you can remove `'django.contrib.messages'` from your `INSTALLED_APPS`, the `MessageMiddleware` line from `MIDDLEWARE`, and the `messages` context processor from `TEMPLATES`.

## Konfigurasi mesin pesan

### Backend Penyimpanan

Kerangka kerja pesan-pesan dapat menggunakan backend berbeda untuk menyimpan pesan-pesan sementara.

Django menyediakan kelas-kelas penyimpanan siap-pakai di `django.contrib.messages`:

class `storage.session.``SessionStorage`

  This class stores all messages inside of the request's session. Therefore it requires Django's `contrib.sessions` application.

class `storage.cookie.``CookieStorage`

  Kelas ini menyimpan data pesan dalam sebuah kue (ditandai dengan campuran rahasia untuk mencegah perubahan) untuk bertahan pemberitahuan terhadap permintaan. Pesan-pesan lama dibuang jika ukuran data kue akan melebihi 2048 byte.

class `storage.fallback.``FallbackStorage`

  This class first uses `CookieStorage`, and falls back to using `SessionStorage` for the messages that could not fit in a single cookie. It also requires Django's `contrib.sessions` application.

  Perilaku ini menghindari menulis ke sesi bilamana memungkinkan. Itu harus menyediakan penampilan terbaik di kasus umum.

`FallbackStorage` adalah kelas penyimpanan awalan. Jika itu tidak cocok pada kebutuhan anda, anda dapat memilih kelas penyimpanan lain dengan mengatur `MESSAGE_STORAGE` ke jalur impor penuhnya, sebagai contoh:

    MESSAGE_STORAGE = 'django.contrib.messages.storage.cookie.CookieStorage'

class `storage.base.``BaseStorage`

Untuk menulis kelas penyimpanan sendiri, subkelas kelas `BaseStorage` di `django.contrib.messages.storage.base` dan menerapkan metode `_get` dan `_store`.

### Tingkatan pesan

The messages framework is based on a configurable level architecture similar to that of the Python logging module. Message levels allow you to group messages by type so they can be filtered or displayed differently in views and templates.

Tingkat siap-pakai, yang dapat diimpor dari `django.contrib.messages` secar langsung, adalah:

Ketetapan | Maksud
--- | ---
`DEBUG` | Development-related messages that will be ignored (or removed) in a production deployment
`INFO` | Pesan informasi untuk pengguna
`BERHASIL` | Sebuah tindakan telah berhasil, sebagai contoh "Profil anda telah berhasil diperbaharui".
`PERINGATAN` | Kegagalan tidak muncul tetapi mungkin sebentar lagi
`KESALAHAN` | Sebuah tindakan tidak berhasil atau beberapa kegagalan lain muncul

The `MESSAGE_LEVEL` setting can be used to change the minimum recorded level (or it can be changed per request). Attempts to add messages of a level less than this will be ignored.

### Etiket pesan

Message tags are a string representation of the message level plus any extra tags that were added directly in the view (see Adding extra message tags below for more details). Tags are stored in a string and are separated by spaces. Typically, message tags are used as CSS classes to customize message style based on message type. By default, each level has a single tag that's a lowercase version of its own constant:

Tingkat Ketetapan | Etiket
--- | ---
`DEBUG` | `debug`
`INFO` | `info`
`BERHASIL` | `berhasil`
`PERINGATAN` | `peringatan`
`KESALAHAN` | `kesalahan`

To change the default tags for a message level (either built-in or custom), set the `MESSAGE_TAGS` setting to a dictionary containing the levels you wish to change. As this extends the default tags, you only need to provide tags for the levels you wish to override:

    from django.contrib.messages import constants as messages
    MESSAGE_TAGS = {
        messages.INFO: '',
        50: 'critical',
    }

## Menggunakan pesan di tampilan dan cetakan

`add_message`(request, level, message, extra_tags='', fail_silently=False)

### Menambahkan pesan

Untuk menambahkan pesan, panggil:

    from django.contrib import messages
    messages.add_message(request, messages.INFO, 'Hello world.')

Some shortcut methods provide a standard way to add messages with commonly used tags (which are usually represented as HTML classes for the message):

    messages.debug(request, '%s SQL statements were executed.' % count)
    messages.info(request, 'Three credits remain in your account.')
    messages.success(request, 'Profile details updated.')
    messages.warning(request, 'Your account expires in three days.')
    messages.error(request, 'Document deleted.')

### Menampilkan pesan

`get_messages`(request)

Di cetakan anda, gunakan sesuatu seperti:

    {% if messages %}
    <ul class="messages">
        {% for message in messages %}
        <li{% if message.tags %} class="{{ message.tags }}"{% endif %}>{{ message }}</li>
        {% endfor %}
    </ul>
    {% endif %}

If you're using the context processor, your template should be rendered with a `RequestContext`. Otherwise, ensure `messages` is available to the template context.

Even if you know there is only just one message, you should still iterate over the `messages` sequence, because otherwise the message storage will not be cleared for the next request.

The context processor also provides a `DEFAULT_MESSAGE_LEVELS` variable which is a mapping of the message level names to their numeric value:

    {% if messages %}
    <ul class="messages">
        {% for message in messages %}
        <li{% if message.tags %} class="{{ message.tags }}"{% endif %}>
            {% if message.level == DEFAULT_MESSAGE_LEVELS.ERROR %}Important: {% endif %}
            {{ message }}
        </li>
        {% endfor %}
    </ul>
    {% endif %}

Diluar Cetakan, anda dapat menggunakan `get_messages()`:

    from django.contrib.messages import get_messages

    storage = get_messages(request)
    for message in storage:
        do_something_with_the_message(message)

For instance, you can fetch all the messages to return them in a JSONResponseMixin instead of a `TemplateResponseMixin`.

`get_messages()` akan mengembalikan sebuah instance dari backend penyimpanan dikonfigurasi

### Kelas `Message`

class `storage.base.``Message`

  When you loop over the list of messages in a template, what you get are instances of the `Message` class. It's quite a simple object, with only a few attributes:

  - `message`: Teks sebenarnya dari pesan.
  - `level`: An integer describing the type of the message (see the message levels section above).
  - `tags`: A string combining all the message's tags (`extra_tags` and `level_tag`) separated by spaces.
  - `extra_tags`: A string containing custom tags for this message, separated by spaces. It's empty by default.
  - `level_tag`: The string representation of the level. By default, it's the lowercase version of the name of the associated constant, but this can be changed if you need by using the `MESSAGE_TAGS` setting.

### Membuat penyesuaian tingkatan pesan

Messages levels are nothing more than integers, so you can define your own level constants and use them to create more customized user feedback, e.g.:

    CRITICAL = 50

    def my_view(request):
        messages.add_message(request, CRITICAL, 'A serious error occurred.')

When creating custom message levels you should be careful to avoid overloading existing levels. The values for the built-in levels are:

Tingkat Ketetapan | Nilai
--- | ---
`DEBUG` | 10
`INFO` | 20
`BERHASIL` | 25
`PERINGATAN` | 30
`KESALAHAN` | 40

If you need to identify the custom levels in your HTML or CSS, you need to provide a mapping via the `MESSAGE_TAGS` setting.

Catatan

Jika anda sedang membuat aplikasi digunakan kembali, itu sangat dianjurkan untuk menggunakan hanya message levels siap-pakai dan jangan bergantung pada penyesuaian tingkat apapun

### Merubah tingkat terekam minimal per-permintaan

Tingkat terekam minimal dapat disetel per permintaan melalui metode `set_level`:

    from django.contrib import messages

    # Change the messages level to ensure the debug message is added.
    messages.set_level(request, messages.DEBUG)
    messages.debug(request, 'Test message...')

    # In another request, record only messages with a level of WARNING and higher
    messages.set_level(request, messages.WARNING)
    messages.success(request, 'Your profile was updated.') # ignored
    messages.warning(request, 'Your account is about to expire.') # recorded

    # Set the messages level back to default.
    messages.set_level(request, None)

Mirip, tingkat efektif saat ini dapat diambil dengan `get_level`:

    from django.contrib import messages
    current_level = messages.get_level(request)

Untuk informasi lebih pada bagaimana fungsi tingkat terekam minimal, lihat Message levels diatas.

### Menambahkan etiket pesan tambahan

Untuk lebih kendali langsung melalui etiket pesan, anda dapat secara pilihan menyediakan string mengandung etiket tambahan ke apapun dari metode tambah:

    messages.add_message(request, messages.INFO, 'Over 9000!', extra_tags='dragonball')
    messages.error(request, 'Email box full', extra_tags='email')

Etiket tambahan ditambahkan sebelum etiket awalan untuk tingkat itu dan ruang terpisah.

### Failing silently when the message framework is disabled

If you're writing a reusable app (or other piece of code) and want to include messaging functionality, but don't want to require your users to enable it if they don't want to, you may pass an additional keyword argument `fail_silently=True` to any of the `add_message` family of methods. For example:

    messages.add_message(
        request, messages.SUCCESS, 'Profile details updated.',
        fail_silently=True,
    )
    messages.info(request, 'Hello world.', fail_silently=True)

Catatan

Setting `fail_silently=True` only hides the `MessageFailure` that would otherwise occur when the messages framework disabled and one attempts to use one of the `add_message` family of methods. It does not hide failures that may occur for other reasons.

### Menambahkan pesan-pesan di tampilan berdasarkan-kelas

class `views.``SuccessMessageMixin`

  Menambah sebuah atribut pesan berhasil pada `FormView` berdasarkan kelas-kelas

  `get_success_message`(cleaned_data)

    `cleaned_data` adalah data dibersihkan dari formulir yang digunakan untuk pembentukan string

Contoh views.py:

    from django.contrib.messages.views import SuccessMessageMixin
    from django.views.generic.edit import CreateView
    from myapp.models import Author

    class AuthorCreate(SuccessMessageMixin, CreateView):
        model = Author
        success_url = '/success/'
        success_message = "%(name)s was created successfully"

The cleaned data from the `form` is available for string interpolation using the `%(field_name)s` syntax. For ModelForms, if you need access to fields from the saved `object` override the `get_success_message()` method.

Contoh views.py untuk ModelForms:

    from django.contrib.messages.views import SuccessMessageMixin
    from django.views.generic.edit import CreateView
    from myapp.models import ComplicatedModel

    class ComplicatedCreate(SuccessMessageMixin, CreateView):
        model = ComplicatedModel
        success_url = '/success/'
        success_message = "%(calculated_field)s was created successfully"

        def get_success_message(self, cleaned_data):
            return self.success_message % dict(
                cleaned_data,
                calculated_field=self.object.calculated_field,
            )

## Pesan berakhir

The messages are marked to be cleared when the storage instance is iterated (and cleared when the response is processed).

Untuk menghindari pesan-pesan sedang dibesihkan, anda dapat menyetel penyimpanan pesan-pesan menjadi `False` setelah perulangan:

    storage = messages.get_messages(request)
    for message in storage:
        do_something_with(message)
    storage.used = False

## Perilaku dari permintaan paralel

Due to the way cookies (and hence sessions) work, the behavior of any backends that make use of cookies or sessions is undefined when the same client makes multiple requests that set or get messages in parallel. For example, if a client initiates a request that creates a message in one window (or tab) and then another that fetches any uniterated messages in another window, before the first window redirects, the message may appear in the second window instead of the first window where it may be expected.

In short, when multiple simultaneous requests from the same client are involved, messages are not guaranteed to be delivered to the same window that created them nor, in some cases, at all. Note that this is typically not a problem in most applications and will become a non-issue in HTML5, where each window/tab will have its own browsing context.

## Pengaturan

Sedikit settings memberikan anda kendali terhadap perilaku pesan:

- `MESSAGE_LEVEL`
- `MESSAGE_STORAGE`
- `MESSAGE_TAGS`

Untuk backend yang menggunakan kue, pengaturan untuk kue diambil dari pengaturan kue sesi:

- `SESSION_COOKIE_DOMAIN`
- `SESSION_COOKIE_SECURE`
- `SESSION_COOKIE_HTTPONLY`