# dokumentasi Django 2.2.9.dev20191202104323

# Acuan obyek terkait

class `RelatedManager`

  A "related manager" is a manager used in a one-to-many or many-to-many related context. This happens in two cases:

  - "other side" dari sebuah hubungan `ForeignKey`. Yaitu:

        from django.db import models

        class Reporter(models.Model):
            # ...
            pass

        class Article(models.Model):
            reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    Dalam contoh diatas, metode-metode dibawah akan tersedia pada pengelola `reporter.article_set`.

  - Kedua sisi dari hubungan `ManyToManyField`:

        class Topping(models.Model):
            # ...
            pass

        class Pizza(models.Model):
            toppings = models.ManyToManyField(Topping)

    Dalam contoh ini, metode-metode dibawah akan tersedia kedua pada `topping.pizza_set` dan pada `pizza.toppings`.

  `add`(*objs, bulk=True, through_defaults=None)

    Menambahkan obyek model ditentukan ke kumpulan obyek terkait.

    Contoh:

        >>> b = Blog.objects.get(id=1)
        >>> e = Entry.objects.get(id=234)
        >>> b.entry_set.add(e) # Associates Entry e with Blog b.

    Dalam contoh diatas, dalam kasus hubungan `ForeignKey`, `QuerySet.update()` digunakan untuk melakukan pembaharuan. Ini membutuhkan obyek-obyek untuk sudah disimpan.

    Anda dapat menggunakan argumen `bulk=False` daripada memiliki pengelola terkait melakukan pembaharuan dengan memanggil `e.save()`.

    Using `add()` with a many-to-many relationship, however, will not call any `save()` methods (the `bulk` argument doesn't exist), but rather create the relationships using `QuerySet.bulk_create()`. If you need to execute some custom logic when a relationship is created, listen to the `m2m_changed` signal, which will trigger `pre_add` and `post_add` actions.

    Menggunakan `ada()` pada hubungan yang sudah ada tidak akan menggandakan hubungan, tetapi itu akan masih memicu sinyal.

    `add()` also accepts the field the relation points to as an argument. The above example can be rewritten as `b.entry_set.add(234)`.

    Use the `through_defaults` argument to specify values for the new intermediate model instance(s), if needed.

    Changed in Django 2.2:

    The `through_defaults` argument was added.

  `create`(through_defaults=None, **kwargs)

    Membuat sebuah obyek baru, menyimpan itu dan menaruh itu dalam kumpulan obyek terkait. Mengembalikan obyek yang baru dibuat:

        >>> b = Blog.objects.get(id=1)
        >>> e = b.entry_set.create(
        ...     headline='Hello',
        ...     body_text='Hi',
        ...     pub_date=datetime.date(2005, 1, 1)
        ... )

        # No need to call e.save() at this point -- it's already been saved.

    Ini adalah setara pada (tetapi lebih sederhana dari):

        >>> b = Blog.objects.get(id=1)
        >>> e = Entry(
        ...     blog=b,
        ...     headline='Hello',
        ...     body_text='Hi',
        ...     pub_date=datetime.date(2005, 1, 1)
        ... )
        >>> e.save(force_insert=True)

    Note that there's no need to specify the keyword argument of the model that defines the relationship. In the above example, we don't pass the parameter `blog` to `create()`. Django figures out that the new `Entry` object's `blog` field should be set to `b`.

    Use the `through_defaults` argument to specify values for the new intermediate model instance, if needed.

    Changed in Django 2.2:

    The `through_defaults` argument was added.

  `remove`(*objs, bulk=True)

    memindahkan pbyek-obyek model tertentu dari kumpulan obyek terkait:

        >>> b = Blog.objects.get(id=1)
        >>> e = Entry.objects.get(id=234)
        >>> b.entry_set.remove(e) # Disassociates Entry e from Blog b.

    Similar to `add()`, `e.save()` is called in the example above to perform the update. Using `remove()` with a many-to-many relationship, however, will delete the relationships using `QuerySet.delete()` which means no model `save()` methods are called; listen to the `m2m_changed` signal if you wish to execute custom code when a relationship is deleted.

    Similarly to `add()`, `remove()` also accepts the field the relation points to as an argument. The above example can be rewritten as `b.entry_set.remove(234)`.

    For `ForeignKey` objects, this method only exists if `null=True`. If the related field can't be set to `None` (`NULL`), then an object can't be removed from a relation without being added to another. In the above example, removing `e` from `b.entry_set()` is equivalent to doing `e.blog = None`, and because the `blog` `ForeignKey` doesn't have `null=True`, this is invalid.

    For `ForeignKey` objects, this method accepts a `bulk` argument to control how to perform the operation. If `True` (the default), `QuerySet.update()` is used. If `bulk=False`, the `save()` method of each individual model instance is called instead. This triggers the `pre_save` and `post_save` signals and comes at the expense of performance.

    Untuk hubungan many-to-many, argumen kata kunci `bulk` tidak ada.

  `clear`(bulk=True)

    Memindahkan semua obyek dari kumpulan obyek terkait:

        >>> b = Blog.objects.get(id=1)
        >>> b.entry_set.clear()

    Catat ini tidak menghapus obyek-obyek terkait -- itu hanya memisahkan mereka.

    Just like `remove()`, `clear()` is only available on `ForeignKey`s where `null=True` and it also accepts the `bulk` keyword argument.

    Untuk hubungan many-to-many, argumen kata kunci `bulk` tidak ada.

  `set`(objs, bulk=True, clear=False, through_defaults=None)

    Ganti kumpulan dari obyek terkait:

        >>> new_list = [obj1, obj2, obj3]
        >>> e.related_set.set(new_list)

    This method accepts a `clear` argument to control how to perform the operation. If `False` (the default), the elements missing from the new set are removed using `remove()` and only the new ones are added. If `clear=True`, the `clear()` method is called instead and the whole set is added at once.

    Untuk obyek `ForeignKey`, argumen `bulk` dilewatkan ke `add()` dan `remove()`.

    Untuk hubungan many-to-many, argumen kata kunci `bulk` tidak ada.

    Note that since `set()` is a compound operation, it is subject to race conditions. For instance, new objects may be added to the database in between the call to `clear()` and the call to `add()`.

    Similarly to `add()`, `set()` also accepts the field the relation points to as an argument. The above example can be rewritten as `e.related_set.set([obj1.pk, obj2.pk, obj3.pk])`.

    Use the `through_defaults` argument to specify values for the new intermediate model instance(s), if needed.

    Changed in Django 2.2:

    The `through_defaults` argument was added.

  Catatan

  Note that `add()`, `create()`, `remove()`, `clear()`, and `set()` all apply database changes immediately for all types of related fields. In other words, there is no need to call `save()` on either end of the relationship.

  Jika anda menggunakan `prefetch_related()`, metode `add()`, `remove()`, `clear()`, dan `set()` memberishkan cache yang terambil.