Le principal problème avec la création et l'ajout de plusieurs champs dans Django est qu'il peut être difficile de gérer correctement les données. En effet, il peut être difficile de savoir quels enregistrements appartiennent à quels champs et il peut être difficile de déterminer quels champs sont requis pour un enregistrement donné.
J'ai un modèle avec un champ plusieurs à plusieurs:
class MyModel(models.Model):
name = models.CharField(max_length=50)
tags = models.ManyToManyField('Tag')
def __unicode__(self):
return self.name
Je veux créer une nouvelle instance de MyModel, et ajoutez une liste de Tag des objets à la tags champ:
my_model = MyModel() # Create new instance of MyModel without saving it yet.
my_model.name = 'foo' # Set the name field on the new instance.
tag1 = Tag() # Create first Tag object without saving it yet.
tag1.name = 'bar' # Set the name field on the first Tag object.
tag2 = Tag() # Create second Tag object without saving it yet.
tag2.name = 'baz' # Set the name field on the second Tag object.
my_model_tags=[tag1, tag2]# Add both tags to my list of tags for my model
my_model=MyModel(tags=my_model_tags)# Add both tags to my model's tags field and save everything in one go!
my_model=MyModel()#Create new instance of MyModel without saving it yet again! This time we'll add some existing Tags from our database instead of creating them from scratch like we did above!
tag3=Tag().objects('id': 1)#Get an existing tag from our database by its id number and store it in a variable called "tag3"
tag4=Tag().objects('id': 2)#Get another existing tag from our database by its id number and store it in a variable called "tag4"
my_model2Tags=[tag3, tag4]#Add both tags (which already exist in our database) to my list of tags for my model this time around!
my_model2=MyModel(tags=myModeltags2)#Add both tags (which already exist in our database) to my model's "tags" field and save everything in one go again! Hooray! Now all four Tags are associated with this one MyModeL instance that we created, two of which were created right here while two others were pulled straight out of our database! All using just two lines each time around too boot!!! :D :D :D Yippee!!! :) :) :) </pre></blockquote><p>Note that you can also do this:</p><blockquote style="margin: 0px 0px 0px 40px;" class="speaker-notes-content-element speaker-notes-content-element--s1" data-highlighted="" data-speaker-notes="" data-end="1518106096000" data-start="1518106096000" tabindex="0" contenteditable="false" spellcheck="false" role="textbox" data-previouscontenteditablevalue="" draggable="true">
myModeltags=[Tag().objects('id': 1), Tag().objects('id': 2)] </pre></blockquote>", "type": "rich", "version": 1}]}], "type": "rich", "version": 1}]}], [{"data": {"text/html": "
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