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Added single and multifield uniqueness constraints

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Harry Marr
2010-01-08 12:04:11 +00:00
parent 45080d3fd1
commit 4d695a3544
7 changed files with 144 additions and 24 deletions
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44
docs/userguide.rst
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@@ -138,6 +138,21 @@ field::
The :class:`User` object is automatically turned into a reference behind the
scenes, and dereferenced when the :class:`Page` object is retrieved.
Uniqueness constraints
^^^^^^^^^^^^^^^^^^^^^^
MongoEngine allows you to specify that a field should be unique across a
collection by providing ``unique=True`` to a :class:`~mongoengine.Field`\ 's
constructor. If you try to save a document that has the same value for a unique
field as a document that is already in the database, a
:class:`~mongoengine.ValidationError` will be raised. You may also specify
multi-field uniqueness constraints by using :attr:`unique_with`, which may be
either a single field name, or a list or tuple of field names::
class User(Document):
username = StringField(unique=True)
first_name = StringField()
last_name = StringField(unique_with='last_name')
Document collections
--------------------
Document classes that inherit **directly** from :class:`~mongoengine.Document`
@@ -172,10 +187,10 @@ Indexes
-------
You can specify indexes on collections to make querying faster. This is done
by creating a list of index specifications called :attr:`indexes` in the
:attr:`~Document.meta` dictionary, where an index specification may either be
a single field name, or a tuple containing multiple field names. A direction
may be specified on fields by prefixing the field name with a **+** or a **-**
sign. Note that direction only matters on multi-field indexes. ::
:attr:`~mongoengine.Document.meta` dictionary, where an index specification may
either be a single field name, or a tuple containing multiple field names. A
direction may be specified on fields by prefixing the field name with a **+**
or a **-** sign. Note that direction only matters on multi-field indexes. ::
class Page(Document):
title = StringField()
@@ -186,11 +201,11 @@ sign. Note that direction only matters on multi-field indexes. ::
Ordering
--------
A default ordering can be specified for your :class:`~mongoengine.queryset.QuerySet`
using the :attr:`ordering` attributeof :attr:`~Document.meta`.
Ordering will be applied when the ``QuerySet`` is created, and can be
overridden by subsequent calls to :meth:`~mongoengine.QuerySet.order_by`. ::
A default ordering can be specified for your
:class:`~mongoengine.queryset.QuerySet` using the :attr:`ordering` attribute of
:attr:`~mongoengine.Document.meta`. Ordering will be applied when the
:class:`~mongoengine.queryset.QuerySet` is created, and can be overridden by
subsequent calls to :meth:`~mongoengine.queryset.QuerySet.order_by`. ::
from datetime import datetime
@@ -202,9 +217,14 @@ overridden by subsequent calls to :meth:`~mongoengine.QuerySet.order_by`. ::
'ordering': ['-published_date']
}
blog_post_1 = BlogPost(title="Blog Post #1", published_date=datetime(2010, 1, 5, 0, 0 ,0))
blog_post_2 = BlogPost(title="Blog Post #2", published_date=datetime(2010, 1, 6, 0, 0 ,0))
blog_post_3 = BlogPost(title="Blog Post #3", published_date=datetime(2010, 1, 7, 0, 0 ,0))
blog_post_1 = BlogPost(title="Blog Post #1")
blog_post_1.published_date = datetime(2010, 1, 5, 0, 0 ,0))
blog_post_2 = BlogPost(title="Blog Post #2")
blog_post_2.published_date = datetime(2010, 1, 6, 0, 0 ,0))
blog_post_3 = BlogPost(title="Blog Post #3")
blog_post_3.published_date = datetime(2010, 1, 7, 0, 0 ,0))
blog_post_1.save()
blog_post_2.save()