Diferencias

Muestra las diferencias entre dos versiones de la página.

--- fw:mongoengine [2014/05/20 10:23]
alfred [In a nutshell]
+++ fw:mongoengine [2020/05/09 09:25] (actual)
@@ Línea 45: / Línea 45: @@
 === Other field objects ===
   * ''tags = ListField(StringField(max_length=30))'', a ''ListField'' is a field object that allows to have a list of other field objects (including other lists).
+  * ''date_modified = DateTimeField(default=datetime.datetime.now)''
-==== One to many relationship ====
+More about this subject in: [[http://docs.mongoengine.org/guide/defining-documents.html#fields]]
+==== Storing an object ====
+<code python>
+Comment.objects.create(text='Me gusta!')
+</code>
+==== Storing an object inside another ====
 <code python>
 class Comment(EmbeddedDocument):
@@ Línea 57: / Línea 62: @@
     tags = ListField(StringField(max_length=30))
     comments = ListField(EmbeddedDocumentField(Comment))
+</code>
+We also could use ''GenericReferenceField'' to reference any kind of document:
+<code python>
+class Bookmark(Document):
+    bookmark_object = GenericReferenceField()
+</code>
+==== Cascade delete ====
+When we define a ''ReferenceField'' we can indicate ''reverse_delete_rule=CASCADE'' to delete all the objects when a referenced object is deleted (it does not work with MapFields neither DictFields).
+<code python>
+class Post(Document):
+    title = StringField(max_length=120, required=True)
+    author = ReferenceField(User, reverse_delete_rule=CASCADE)
+    tags = ListField(StringField(max_length=30))
+    comments = ListField(EmbeddedDocumentField(Comment))
+</code>
+Other constans we can pass:
+  * ''mongoengine.DO_NOTHING''
+  * ''mongoengine.DENY''
+  * ''mongoengine.NULLIFY''
+  * ''mongoengine.CASCADE''
+  * ''mongoengine.PULL''
+==== Dynamic documents ====
+DynamicDocument documents work like Document but any data or attributes set to them will also be saved (fields cannot start with _ ).
+<code>
+from mongoengine import *
+class Page(DynamicDocument):
+    title = StringField(max_length=200, required=True)
+# Create a new page and add tags
+page = Page(title='Using MongoEngine')
+page.tags = ['mongodb', 'mongoengine']
+page.save()
+</code>
+==== Defining constraints ====
+We can specify field uniqueness with ''unique=True'' and multi-fielduniqueness with ''unique_with'' (for a field name, or a list, or a tuple):
+<code python>
+class User(Document):
+    username = StringField(unique=True)
+    first_name = StringField()
+    last_name = StringField(unique_with='first_name')
+</code>
+===== Editing Data =====
+==== Adding documents ====
+<code python>
+ross = User(email='ross@example.com', first_name='Ross', last_name='Lawley').save()
+# this is other way to save ross
+ross1 = User(email='ross1@example.com')
+ross1.first_name = 'Ross1'
+ross1.last_name = 'Lawley'
+ross1.save()
+post1 = TextPost(title='Fun with MongoEngine', author=john)
+post1.content = 'Took a look at MongoEngine today, looks pretty cool.'
+post1.tags = ['mongodb', 'mongoengine']
+post1.save()
+post2 = LinkPost(title='MongoEngine Documentation', author=ross)
+post2.link_url = 'http://docs.mongoengine.com/'
+post2.tags = ['mongoengine']
+post2.save()
+</code>
+===== Accessing data =====
+A ''Document'' object is actually a ''QuerySet'' object. It lazily queries the database when you need the data. ''QuerySet'' objects perform searches on the data base using functions like...
+  * ''first()'' to retrieve the first object that matches with the provided query.
+  * ''count()'' to know the number of objects that matche with the provided query.
+==== Examples ====
+=== Retrieving all the post titles ===
+<code python>
+for post in Post.objects:
+    print post.title
+</code>
+=== Retrieving a concrete type content ===
+<code python>
+for post in TextPost.objects:
+    print post.content
+</code>
+=== Searching by tag ===
+<code python>
+for post in Post.objects(tags='mongodb'):
+    print post.title
+</code>
+===== Others =====
+==== Django support ====
+=== Connecting ===
+You only need to call ''connect()'' somewhere in the settings module.
+If you were not using another Database backend you may need to add a dummy database:
+<code python>
+DATABASES = {
+    'default': {
+        'ENGINE': 'django.db.backends.dummy'
+    }
+}
+</code>
+=== Users ===
+Django authentication classes are included as Document classes so they are compatible. To enable them you should add the following to your settings.py file:
+<code python>
+AUTHENTICATION_BACKENDS = (
+    'mongoengine.django.auth.MongoEngineBackend',
+)
+</code>
+Remember to call ''set_password()'' method in ''User'' class when assign a password value:
+<code python>
+instance.set_password(attrs.get('password', instance.password))
 </code>

Programming

Herramientas de usuario

Herramientas del sitio

Diferencias

Herramientas de la página