{"title":"Hubungan satu-ke-satu","version":"1.10","locale":"id","docname":"topics/db/examples/one_to_one","url":"/id/1.10/topics/db/examples/one_to_one/","canonical":"https://djangodocs.dev/id/1.10/topics/db/examples/one_to_one/","summary":"Untuk menentukan hubungan satu-ke-satu, gunakan OneToOneField . Dalam contoh ini, sebuah pilihan Place dapat menjadi sebuah Restaurant : Code Copy from django.db…","html":"

Hubungan satu-ke-satuLink to this heading#

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Untuk menentukan hubungan satu-ke-satu, gunakan OneToOneField.

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Dalam contoh ini, sebuah pilihan Place dapat menjadi sebuah Restaurant:

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Code
from django.db import models\n\nclass Place(models.Model):\n    name = models.CharField(max_length=50)\n    address = models.CharField(max_length=80)\n\n    def __str__(self):              # __unicode__ on Python 2\n        return "%s the place" % self.name\n\nclass Restaurant(models.Model):\n    place = models.OneToOneField(\n        Place,\n        on_delete=models.CASCADE,\n        primary_key=True,\n    )\n    serves_hot_dogs = models.BooleanField(default=False)\n    serves_pizza = models.BooleanField(default=False)\n\n    def __str__(self):              # __unicode__ on Python 2\n        return "%s the restaurant" % self.place.name\n\nclass Waiter(models.Model):\n    restaurant = models.ForeignKey(Restaurant, on_delete=models.CASCADE)\n    name = models.CharField(max_length=50)\n\n    def __str__(self):              # __unicode__ on Python 2\n        return "%s the waiter at %s" % (self.name, self.restaurant)\n
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Apa yang mengikuti adalah contoh-contoh dari tindakan yang dapat dilakukan menggunakan fasilitas API Python.

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Buat sepasang Place:

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Python console
>>> p1 = Place(name='Demon Dogs', address='944 W. Fullerton')\n>>> p1.save()\n>>> p2 = Place(name='Ace Hardware', address='1013 N. Ashland')\n>>> p2.save()\n
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Buat sebuah restoran. Lewatkan ID dari obyek "parent" seperti ini ID obyek:

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Python console
>>> r = Restaurant(place=p1, serves_hot_dogs=True, serves_pizza=False)\n>>> r.save()\n
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Sebuah Restaurant dapat mengakses tempatnya:

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Python console
>>> r.place\n<Place: Demon Dogs the place>\n
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Sebuah Place dapat mengakses restorannya, jika tersedia:

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Python console
>>> p1.restaurant\n<Restaurant: Demon Dogs the restaurant>\n
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p2 tidak mempunyai restoran terkait:

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Python console
>>> from django.core.exceptions import ObjectDoesNotExist\n>>> try:\n>>>     p2.restaurant\n>>> except ObjectDoesNotExist:\n>>>     print("There is no restaurant here.")\nThere is no restaurant here.\n
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Anda dapat juga menggunakan hasattr untuk menghindari kebutuhan untuk menangkap pengecualian:

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Python console
>>> hasattr(p2, 'restaurant')\nFalse\n
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Setel tempat menggunakan penugasan catatan. Karena tempat adalah primary key pada Restaurant, penyimpanan akan membuat sebuah restoran baru:

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Python console
>>> r.place = p2\n>>> r.save()\n>>> p2.restaurant\n<Restaurant: Ace Hardware the restaurant>\n>>> r.place\n<Place: Ace Hardware the place>\n
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Setel tempat kembali lagi, menggunakan penugasan dalam membalikkan arah:

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Python console
>>> p1.restaurant = r\n>>> p1.restaurant\n<Restaurant: Demon Dogs the restaurant>\n
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Catat bahwa anda harus menyimpan sebuah obyek sebelum itu dapat diberikan ke hubungan one-to-one. Sebagai contoh, membuat Restaurant dengan Place tidak disimpan memunculkan ValueError:

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Python console
>>> p3 = Place(name='Demon Dogs', address='944 W. Fullerton')\n>>> Restaurant.objects.create(place=p3, serves_hot_dogs=True, serves_pizza=False)\nTraceback (most recent call last):\n...\nValueError: save() prohibited to prevent data loss due to unsaved related object 'place'.\n
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Restaurant.objects.all() hanya mengembalikan Restaurants, bukan the Places. Catat bahwa ada dua restoran - Ace Hardware Restaurant telah dibuat di panggilan pada r.place = p2:

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Python console
>>> Restaurant.objects.all()\n<QuerySet [<Restaurant: Demon Dogs the restaurant>, <Restaurant: Ace Hardware the restaurant>]>\n
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Place.objects.all() mengembalikan semua Places, tanpa memperhatikan apakah mereka mempunyai Restaurants:

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Python console
>>> Place.objects.order_by('name')\n<QuerySet [<Place: Ace Hardware the place>, <Place: Demon Dogs the place>]>\n
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Anda dapat meminta model menggunakan lookups across relationships:

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Python console
>>> Restaurant.objects.get(place=p1)\n<Restaurant: Demon Dogs the restaurant>\n>>> Restaurant.objects.get(place__pk=1)\n<Restaurant: Demon Dogs the restaurant>\n>>> Restaurant.objects.filter(place__name__startswith="Demon")\n<QuerySet [<Restaurant: Demon Dogs the restaurant>]>\n>>> Restaurant.objects.exclude(place__address__contains="Ashland")\n<QuerySet [<Restaurant: Demon Dogs the restaurant>]>\n
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Perjalanan ini bekerja dalam membalikkan:

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Python console
>>> Place.objects.get(pk=1)\n<Place: Demon Dogs the place>\n>>> Place.objects.get(restaurant__place=p1)\n<Place: Demon Dogs the place>\n>>> Place.objects.get(restaurant=r)\n<Place: Demon Dogs the place>\n>>> Place.objects.get(restaurant__place__name__startswith="Demon")\n<Place: Demon Dogs the place>\n
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Tambah Waiter ke Restaurant:

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Python console
>>> w = r.waiter_set.create(name='Joe')\n>>> w\n<Waiter: Joe the waiter at Demon Dogs the restaurant>\n
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Meminta pelayan:

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Python console
>>> Waiter.objects.filter(restaurant__place=p1)\n<QuerySet [<Waiter: Joe the waiter at Demon Dogs the restaurant>]>\n>>> Waiter.objects.filter(restaurant__place__name__startswith="Demon")\n<QuerySet [<Waiter: Joe the waiter at Demon Dogs the restaurant>]>\n
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