mirror of
				https://github.com/django/django.git
				synced 2025-10-31 09:41:08 +00:00 
			
		
		
		
	[5.0.x] Added missing pycon directives in various docs.
Backport of 718b32c691 from main
			
			
This commit is contained in:
		| @@ -1246,25 +1246,31 @@ blue. | ||||
|     sources (using the sample data from the GeoDjango tests; see also the | ||||
|     :ref:`gdal_sample_data` section). | ||||
|  | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> from django.contrib.gis.gdal import GDALRaster | ||||
|         >>> rst = GDALRaster('/path/to/your/raster.tif', write=False) | ||||
|         >>> rst = GDALRaster("/path/to/your/raster.tif", write=False) | ||||
|         >>> rst.name | ||||
|         '/path/to/your/raster.tif' | ||||
|         >>> rst.width, rst.height  # This file has 163 x 174 pixels | ||||
|         (163, 174) | ||||
|         >>> rst = GDALRaster({  # Creates an in-memory raster | ||||
|         ...     'srid': 4326, | ||||
|         ...     'width': 4, | ||||
|         ...     'height': 4, | ||||
|         ...     'datatype': 1, | ||||
|         ...     'bands': [{ | ||||
|         ...         'data': (2, 3), | ||||
|         ...         'offset': (1, 1), | ||||
|         ...         'size': (2, 2), | ||||
|         ...         'shape': (2, 1), | ||||
|         ...         'nodata_value': 5, | ||||
|         ...     }] | ||||
|         ... }) | ||||
|         >>> rst = GDALRaster( | ||||
|         ...     {  # Creates an in-memory raster | ||||
|         ...         "srid": 4326, | ||||
|         ...         "width": 4, | ||||
|         ...         "height": 4, | ||||
|         ...         "datatype": 1, | ||||
|         ...         "bands": [ | ||||
|         ...             { | ||||
|         ...                 "data": (2, 3), | ||||
|         ...                 "offset": (1, 1), | ||||
|         ...                 "size": (2, 2), | ||||
|         ...                 "shape": (2, 1), | ||||
|         ...                 "nodata_value": 5, | ||||
|         ...             } | ||||
|         ...         ], | ||||
|         ...     } | ||||
|         ... ) | ||||
|         >>> rst.srs.srid | ||||
|         4326 | ||||
|         >>> rst.width, rst.height | ||||
| @@ -1274,7 +1280,7 @@ blue. | ||||
|                [5, 2, 3, 5], | ||||
|                [5, 2, 3, 5], | ||||
|                [5, 5, 5, 5]], dtype=uint8) | ||||
|         >>> rst_file = open('/path/to/your/raster.tif', 'rb') | ||||
|         >>> rst_file = open("/path/to/your/raster.tif", "rb") | ||||
|         >>> rst_bytes = rst_file.read() | ||||
|         >>> rst = GDALRaster(rst_bytes) | ||||
|         >>> rst.is_vsi_based | ||||
| @@ -1291,7 +1297,9 @@ blue. | ||||
|         The name of the source which is equivalent to the input file path or the name | ||||
|         provided upon instantiation. | ||||
|  | ||||
|             >>> GDALRaster({'width': 10, 'height': 10, 'name': 'myraster', 'srid': 4326}).name | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> GDALRaster({"width": 10, "height": 10, "name": "myraster", "srid": 4326}).name | ||||
|             'myraster' | ||||
|  | ||||
|     .. attribute:: driver | ||||
| @@ -1306,15 +1314,27 @@ blue. | ||||
|  | ||||
|         An in-memory raster is created through the following example: | ||||
|  | ||||
|             >>> GDALRaster({'width': 10, 'height': 10, 'srid': 4326}).driver.name | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> GDALRaster({"width": 10, "height": 10, "srid": 4326}).driver.name | ||||
|             'MEM' | ||||
|  | ||||
|         A file based GeoTiff raster is created through the following example: | ||||
|  | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> import tempfile | ||||
|             >>> rstfile = tempfile.NamedTemporaryFile(suffix='.tif') | ||||
|             >>> rst = GDALRaster({'driver': 'GTiff', 'name': rstfile.name, 'srid': 4326, | ||||
|             ...                   'width': 255, 'height': 255, 'nr_of_bands': 1}) | ||||
|             >>> rstfile = tempfile.NamedTemporaryFile(suffix=".tif") | ||||
|             >>> rst = GDALRaster( | ||||
|             ...     { | ||||
|             ...         "driver": "GTiff", | ||||
|             ...         "name": rstfile.name, | ||||
|             ...         "srid": 4326, | ||||
|             ...         "width": 255, | ||||
|             ...         "height": 255, | ||||
|             ...         "nr_of_bands": 1, | ||||
|             ...     } | ||||
|             ... ) | ||||
|             >>> rst.name | ||||
|             '/tmp/tmp7x9H4J.tif'           # The exact filename will be different on your computer | ||||
|             >>> rst.driver.name | ||||
| @@ -1324,14 +1344,18 @@ blue. | ||||
|  | ||||
|         The width of the source in pixels (X-axis). | ||||
|  | ||||
|             >>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).width | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> GDALRaster({"width": 10, "height": 20, "srid": 4326}).width | ||||
|             10 | ||||
|  | ||||
|     .. attribute:: height | ||||
|  | ||||
|         The height of the source in pixels (Y-axis). | ||||
|  | ||||
|             >>> GDALRaster({'width': 10, 'height': 20, 'srid': 4326}).height | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> GDALRaster({"width": 10, "height": 20, "srid": 4326}).height | ||||
|             20 | ||||
|  | ||||
|     .. attribute:: srs | ||||
| @@ -1341,7 +1365,9 @@ blue. | ||||
|         setting it to an other :class:`SpatialReference` or providing any input | ||||
|         that is accepted by the :class:`SpatialReference` constructor. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.srs.srid | ||||
|             4326 | ||||
|             >>> rst.srs = 3086 | ||||
| @@ -1354,7 +1380,9 @@ blue. | ||||
|         property is a shortcut to getting or setting the SRID through the | ||||
|         :attr:`srs` attribute. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.srid | ||||
|             4326 | ||||
|             >>> rst.srid = 3086 | ||||
| @@ -1378,7 +1406,9 @@ blue. | ||||
|  | ||||
|         The default is ``[0.0, 1.0, 0.0, 0.0, 0.0, -1.0]``. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.geotransform | ||||
|             [0.0, 1.0, 0.0, 0.0, 0.0, -1.0] | ||||
|  | ||||
| @@ -1388,7 +1418,9 @@ blue. | ||||
|         reference system of the source, as a point object with ``x`` and ``y`` | ||||
|         members. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.origin | ||||
|             [0.0, 0.0] | ||||
|             >>> rst.origin.x = 1 | ||||
| @@ -1401,7 +1433,9 @@ blue. | ||||
|         object with ``x`` and ``y``  members. See :attr:`geotransform` for more | ||||
|         information. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.scale | ||||
|             [1.0, -1.0] | ||||
|             >>> rst.scale.x = 2 | ||||
| @@ -1414,7 +1448,9 @@ blue. | ||||
|         with ``x`` and ``y``  members. In case of north up images, these | ||||
|         coefficients are both ``0``. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.skew | ||||
|             [0.0, 0.0] | ||||
|             >>> rst.skew.x = 3 | ||||
| @@ -1427,7 +1463,9 @@ blue. | ||||
|         ``(xmin, ymin, xmax, ymax)`` in the spatial reference system of the | ||||
|         source. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.extent | ||||
|             (0.0, -20.0, 10.0, 0.0) | ||||
|             >>> rst.origin.x = 100 | ||||
| @@ -1438,8 +1476,16 @@ blue. | ||||
|  | ||||
|         List of all bands of the source, as :class:`GDALBand` instances. | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 1, "height": 2, 'srid': 4326, | ||||
|             ...                   "bands": [{"data": [0, 1]}, {"data": [2, 3]}]}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster( | ||||
|             ...     { | ||||
|             ...         "width": 1, | ||||
|             ...         "height": 2, | ||||
|             ...         "srid": 4326, | ||||
|             ...         "bands": [{"data": [0, 1]}, {"data": [2, 3]}], | ||||
|             ...     } | ||||
|             ... ) | ||||
|             >>> len(rst.bands) | ||||
|             2 | ||||
|             >>> rst.bands[1].data() | ||||
| @@ -1482,12 +1528,18 @@ blue. | ||||
|         For example, the warp function can be used for aggregating a raster to | ||||
|         the double of its original pixel scale: | ||||
|  | ||||
|             >>> rst = GDALRaster({ | ||||
|             ...     "width": 6, "height": 6, "srid": 3086, | ||||
|             ...     "origin": [500000, 400000], | ||||
|             ...     "scale": [100, -100], | ||||
|             ...     "bands": [{"data": range(36), "nodata_value": 99}] | ||||
|             ... }) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster( | ||||
|             ...     { | ||||
|             ...         "width": 6, | ||||
|             ...         "height": 6, | ||||
|             ...         "srid": 3086, | ||||
|             ...         "origin": [500000, 400000], | ||||
|             ...         "scale": [100, -100], | ||||
|             ...         "bands": [{"data": range(36), "nodata_value": 99}], | ||||
|             ...     } | ||||
|             ... ) | ||||
|             >>> target = rst.warp({"scale": [200, -200], "width": 3, "height": 3}) | ||||
|             >>> target.bands[0].data() | ||||
|             array([[  7.,   9.,  11.], | ||||
| @@ -1516,12 +1568,18 @@ blue. | ||||
|         argument. Consult the :attr:`~GDALRaster.warp` documentation for detail | ||||
|         on those arguments. | ||||
|  | ||||
|             >>> rst = GDALRaster({ | ||||
|             ...     "width": 6, "height": 6, "srid": 3086, | ||||
|             ...     "origin": [500000, 400000], | ||||
|             ...     "scale": [100, -100], | ||||
|             ...     "bands": [{"data": range(36), "nodata_value": 99}] | ||||
|             ... }) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster( | ||||
|             ...     { | ||||
|             ...         "width": 6, | ||||
|             ...         "height": 6, | ||||
|             ...         "srid": 3086, | ||||
|             ...         "origin": [500000, 400000], | ||||
|             ...         "scale": [100, -100], | ||||
|             ...         "bands": [{"data": range(36), "nodata_value": 99}], | ||||
|             ...     } | ||||
|             ... ) | ||||
|             >>> target_srs = SpatialReference(4326) | ||||
|             >>> target = rst.transform(target_srs) | ||||
|             >>> target.origin | ||||
| @@ -1547,13 +1605,15 @@ blue. | ||||
|  | ||||
|         To remove a metadata item, use ``None`` as the metadata value. | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 10, 'height': 20, 'srid': 4326}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster({"width": 10, "height": 20, "srid": 4326}) | ||||
|             >>> rst.metadata | ||||
|             {} | ||||
|             >>> rst.metadata = {'DEFAULT': {'OWNER': 'Django', 'VERSION': '1.0'}} | ||||
|             >>> rst.metadata = {"DEFAULT": {"OWNER": "Django", "VERSION": "1.0"}} | ||||
|             >>> rst.metadata | ||||
|             {'DEFAULT': {'OWNER': 'Django', 'VERSION': '1.0'}} | ||||
|             >>> rst.metadata = {'DEFAULT': {'OWNER': None, 'VERSION': '2.0'}} | ||||
|             >>> rst.metadata = {"DEFAULT": {"OWNER": None, "VERSION": "2.0"}} | ||||
|             >>> rst.metadata | ||||
|             {'DEFAULT': {'VERSION': '2.0'}} | ||||
|  | ||||
| @@ -1691,7 +1751,11 @@ blue. | ||||
|  | ||||
|         For example: | ||||
|  | ||||
|             >>> rst = GDALRaster({'width': 4, 'height': 4, 'srid': 4326, 'datatype': 1, 'nr_of_bands': 1}) | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> rst = GDALRaster( | ||||
|             ...     {"width": 4, "height": 4, "srid": 4326, "datatype": 1, "nr_of_bands": 1} | ||||
|             ... ) | ||||
|             >>> bnd = rst.bands[0] | ||||
|             >>> bnd.data(range(16)) | ||||
|             >>> bnd.data() | ||||
| @@ -1708,7 +1772,7 @@ blue. | ||||
|                    [ 4, -1, -2,  7], | ||||
|                    [ 8, -3, -4, 11], | ||||
|                    [12, 13, 14, 15]], dtype=int8) | ||||
|             >>> bnd.data(data='\x9d\xa8\xb3\xbe', offset=(1, 1), size=(2, 2)) | ||||
|             >>> bnd.data(data="\x9d\xa8\xb3\xbe", offset=(1, 1), size=(2, 2)) | ||||
|             >>> bnd.data() | ||||
|             array([[  0,   1,   2,   3], | ||||
|                    [  4, -99, -88,   7], | ||||
|   | ||||
| @@ -94,13 +94,17 @@ Examples: | ||||
|  | ||||
| .. _Full Text Search docs: https://www.postgresql.org/docs/current/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> from django.contrib.postgres.search import SearchQuery | ||||
|     >>> SearchQuery('red tomato')  # two keywords | ||||
|     >>> SearchQuery('tomato red')  # same results as above | ||||
|     >>> SearchQuery('red tomato', search_type='phrase')  # a phrase | ||||
|     >>> SearchQuery('tomato red', search_type='phrase')  # a different phrase | ||||
|     >>> SearchQuery("'tomato' & ('red' | 'green')", search_type='raw')  # boolean operators | ||||
|     >>> SearchQuery("'tomato' ('red' OR 'green')", search_type='websearch')  # websearch operators | ||||
|     >>> SearchQuery("red tomato")  # two keywords | ||||
|     >>> SearchQuery("tomato red")  # same results as above | ||||
|     >>> SearchQuery("red tomato", search_type="phrase")  # a phrase | ||||
|     >>> SearchQuery("tomato red", search_type="phrase")  # a different phrase | ||||
|     >>> SearchQuery("'tomato' & ('red' | 'green')", search_type="raw")  # boolean operators | ||||
|     >>> SearchQuery( | ||||
|     ...     "'tomato' ('red' OR 'green')", search_type="websearch" | ||||
|     ... )  # websearch operators | ||||
|  | ||||
| ``SearchQuery`` terms can be combined logically to provide more flexibility: | ||||
|  | ||||
|   | ||||
| @@ -148,6 +148,8 @@ if validation has side effects, those side effects will only be triggered once. | ||||
| Returns a ``dict`` that maps fields to their original ``ValidationError`` | ||||
| instances. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> f.errors.as_data() | ||||
|     {'sender': [ValidationError(['Enter a valid email address.'])], | ||||
|     'subject': [ValidationError(['This field is required.'])]} | ||||
| @@ -170,6 +172,8 @@ messages in ``Form.errors``. | ||||
|  | ||||
| Returns the errors serialized as JSON. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> f.errors.as_json() | ||||
|     {"sender": [{"message": "Enter a valid email address.", "code": "invalid"}], | ||||
|     "subject": [{"message": "This field is required.", "code": "required"}]} | ||||
| @@ -325,10 +329,14 @@ Checking which form data has changed | ||||
| Use the ``has_changed()`` method on your ``Form`` when you need to check if the | ||||
| form data has been changed from the initial data. | ||||
|  | ||||
|     >>> data = {'subject': 'hello', | ||||
|     ...         'message': 'Hi there', | ||||
|     ...         'sender': 'foo@example.com', | ||||
|     ...         'cc_myself': True} | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> data = { | ||||
|     ...     "subject": "hello", | ||||
|     ...     "message": "Hi there", | ||||
|     ...     "sender": "foo@example.com", | ||||
|     ...     "cc_myself": True, | ||||
|     ... } | ||||
|     >>> f = ContactForm(data, initial=data) | ||||
|     >>> f.has_changed() | ||||
|     False | ||||
| @@ -336,6 +344,8 @@ form data has been changed from the initial data. | ||||
| When the form is submitted, we reconstruct it and provide the original data | ||||
| so that the comparison can be done: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> f = ContactForm(request.POST, initial=data) | ||||
|     >>> f.has_changed() | ||||
|  | ||||
| @@ -350,9 +360,12 @@ The ``changed_data`` attribute returns a list of the names of the fields whose | ||||
| values in the form's bound data (usually ``request.POST``) differ from what was | ||||
| provided in :attr:`~Form.initial`. It returns an empty list if no data differs. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> f = ContactForm(request.POST, initial=data) | ||||
|     >>> if f.has_changed(): | ||||
|     ...     print("The following fields changed: %s" % ", ".join(f.changed_data)) | ||||
|     ... | ||||
|     >>> f.changed_data | ||||
|     ['subject', 'message'] | ||||
|  | ||||
|   | ||||
| @@ -1187,11 +1187,13 @@ Slightly complex built-in ``Field`` classes | ||||
|         The list of fields that should be used to validate the field's value (in | ||||
|         the order in which they are provided). | ||||
|  | ||||
|         .. code-block:: pycon | ||||
|  | ||||
|             >>> from django.forms import ComboField | ||||
|             >>> f = ComboField(fields=[CharField(max_length=20), EmailField()]) | ||||
|             >>> f.clean('test@example.com') | ||||
|             >>> f.clean("test@example.com") | ||||
|             'test@example.com' | ||||
|             >>> f.clean('longemailaddress@example.com') | ||||
|             >>> f.clean("longemailaddress@example.com") | ||||
|             Traceback (most recent call last): | ||||
|             ... | ||||
|             ValidationError: ['Ensure this value has at most 20 characters (it has 28).'] | ||||
|   | ||||
| @@ -89,11 +89,13 @@ Usage examples: | ||||
|     A Python value passed to ``Coalesce`` on MySQL may be converted to an | ||||
|     incorrect type unless explicitly cast to the correct database type: | ||||
|  | ||||
|     >>> from django.db.models import DateTimeField | ||||
|     >>> from django.db.models.functions import Cast, Coalesce | ||||
|     >>> from django.utils import timezone | ||||
|     >>> now = timezone.now() | ||||
|     >>> Coalesce('updated', Cast(now, DateTimeField())) | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> from django.db.models import DateTimeField | ||||
|         >>> from django.db.models.functions import Cast, Coalesce | ||||
|         >>> from django.utils import timezone | ||||
|         >>> now = timezone.now() | ||||
|         >>> Coalesce("updated", Cast(now, DateTimeField())) | ||||
|  | ||||
| ``Collate`` | ||||
| ----------- | ||||
|   | ||||
| @@ -997,6 +997,8 @@ databases don't allow ``LIMIT`` or ``OFFSET`` in the combined queries. | ||||
| Uses SQL's ``INTERSECT`` operator to return the shared elements of two or more | ||||
| ``QuerySet``\s. For example: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> qs1.intersection(qs2, qs3) | ||||
|  | ||||
| See :meth:`union` for some restrictions. | ||||
| @@ -1197,7 +1199,9 @@ item in the Pizza ``QuerySet``. | ||||
|  | ||||
| We can reduce to just two queries using ``prefetch_related``: | ||||
|  | ||||
|     >>> Pizza.objects.prefetch_related('toppings') | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> Pizza.objects.prefetch_related("toppings") | ||||
|  | ||||
| This implies a ``self.toppings.all()`` for each ``Pizza``; now each time | ||||
| ``self.toppings.all()`` is called, instead of having to go to the database for | ||||
| @@ -1241,7 +1245,9 @@ database. | ||||
|     results, and retrieve data using a fresh database query. So, if you write | ||||
|     the following: | ||||
|  | ||||
|         >>> pizzas = Pizza.objects.prefetch_related('toppings') | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> pizzas = Pizza.objects.prefetch_related("toppings") | ||||
|         >>> [list(pizza.toppings.filter(spicy=True)) for pizza in pizzas] | ||||
|  | ||||
|     ...then the fact that ``pizza.toppings.all()`` has been prefetched will not | ||||
| @@ -1301,7 +1307,9 @@ Chaining ``prefetch_related`` calls will accumulate the lookups that are | ||||
| prefetched. To clear any ``prefetch_related`` behavior, pass ``None`` as a | ||||
| parameter: | ||||
|  | ||||
|    >>> non_prefetched = qs.prefetch_related(None) | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> non_prefetched = qs.prefetch_related(None) | ||||
|  | ||||
| One difference to note when using ``prefetch_related`` is that objects created | ||||
| by a query can be shared between the different objects that they are related to | ||||
| @@ -1332,20 +1340,28 @@ the prefetch operation. | ||||
| In its simplest form ``Prefetch`` is equivalent to the traditional string based | ||||
| lookups: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> from django.db.models import Prefetch | ||||
|     >>> Restaurant.objects.prefetch_related(Prefetch('pizzas__toppings')) | ||||
|     >>> Restaurant.objects.prefetch_related(Prefetch("pizzas__toppings")) | ||||
|  | ||||
| You can provide a custom queryset with the optional ``queryset`` argument. | ||||
| This can be used to change the default ordering of the queryset: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('pizzas__toppings', queryset=Toppings.objects.order_by('name'))) | ||||
|     ...     Prefetch("pizzas__toppings", queryset=Toppings.objects.order_by("name")) | ||||
|     ... ) | ||||
|  | ||||
| Or to call :meth:`~django.db.models.query.QuerySet.select_related()` when | ||||
| applicable to reduce the number of queries even further: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> Pizza.objects.prefetch_related( | ||||
|     ...     Prefetch('restaurants', queryset=Restaurant.objects.select_related('best_pizza'))) | ||||
|     ...     Prefetch("restaurants", queryset=Restaurant.objects.select_related("best_pizza")) | ||||
|     ... ) | ||||
|  | ||||
| You can also assign the prefetched result to a custom attribute with the optional | ||||
| ``to_attr`` argument. The result will be stored directly in a list. | ||||
| @@ -1353,32 +1369,42 @@ You can also assign the prefetched result to a custom attribute with the optiona | ||||
| This allows prefetching the same relation multiple times with a different | ||||
| ``QuerySet``; for instance: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> vegetarian_pizzas = Pizza.objects.filter(vegetarian=True) | ||||
|     >>> Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('pizzas', to_attr='menu'), | ||||
|     ...     Prefetch('pizzas', queryset=vegetarian_pizzas, to_attr='vegetarian_menu')) | ||||
|     ...     Prefetch("pizzas", to_attr="menu"), | ||||
|     ...     Prefetch("pizzas", queryset=vegetarian_pizzas, to_attr="vegetarian_menu"), | ||||
|     ... ) | ||||
|  | ||||
| Lookups created with custom ``to_attr`` can still be traversed as usual by other | ||||
| lookups: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> vegetarian_pizzas = Pizza.objects.filter(vegetarian=True) | ||||
|     >>> Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('pizzas', queryset=vegetarian_pizzas, to_attr='vegetarian_menu'), | ||||
|     ...     'vegetarian_menu__toppings') | ||||
|     ...     Prefetch("pizzas", queryset=vegetarian_pizzas, to_attr="vegetarian_menu"), | ||||
|     ...     "vegetarian_menu__toppings", | ||||
|     ... ) | ||||
|  | ||||
| Using ``to_attr`` is recommended when filtering down the prefetch result as it is | ||||
| less ambiguous than storing a filtered result in the related manager's cache: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> queryset = Pizza.objects.filter(vegetarian=True) | ||||
|     >>> | ||||
|     >>> # Recommended: | ||||
|     >>> restaurants = Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('pizzas', queryset=queryset, to_attr='vegetarian_pizzas')) | ||||
|     ...     Prefetch("pizzas", queryset=queryset, to_attr="vegetarian_pizzas") | ||||
|     ... ) | ||||
|     >>> vegetarian_pizzas = restaurants[0].vegetarian_pizzas | ||||
|     >>> | ||||
|     >>> # Not recommended: | ||||
|     >>> restaurants = Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('pizzas', queryset=queryset)) | ||||
|     ...     Prefetch("pizzas", queryset=queryset), | ||||
|     ... ) | ||||
|     >>> vegetarian_pizzas = restaurants[0].pizzas.all() | ||||
|  | ||||
| Custom prefetching also works with single related relations like | ||||
| @@ -1394,10 +1420,13 @@ where prefetching with a custom ``QuerySet`` is useful: | ||||
| * You want to use performance optimization techniques like | ||||
|   :meth:`deferred fields <defer()>`: | ||||
|  | ||||
|     >>> queryset = Pizza.objects.only('name') | ||||
|   .. code-block:: pycon | ||||
|  | ||||
|     >>> queryset = Pizza.objects.only("name") | ||||
|     >>> | ||||
|     >>> restaurants = Restaurant.objects.prefetch_related( | ||||
|     ...     Prefetch('best_pizza', queryset=queryset)) | ||||
|     ...     Prefetch("best_pizza", queryset=queryset) | ||||
|     ... ) | ||||
|  | ||||
| When using multiple databases, ``Prefetch`` will respect your choice of | ||||
| database. If the inner query does not specify a database, it will use the | ||||
| @@ -1427,20 +1456,26 @@ database selected by the outer query. All of the following are valid: | ||||
|  | ||||
|     Take the following examples: | ||||
|  | ||||
|        >>> prefetch_related('pizzas__toppings', 'pizzas') | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|        >>> prefetch_related("pizzas__toppings", "pizzas") | ||||
|  | ||||
|     This works even though it's unordered because ``'pizzas__toppings'`` | ||||
|     already contains all the needed information, therefore the second argument | ||||
|     ``'pizzas'`` is actually redundant. | ||||
|  | ||||
|         >>> prefetch_related('pizzas__toppings', Prefetch('pizzas', queryset=Pizza.objects.all())) | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> prefetch_related("pizzas__toppings", Prefetch("pizzas", queryset=Pizza.objects.all())) | ||||
|  | ||||
|     This will raise a ``ValueError`` because of the attempt to redefine the | ||||
|     queryset of a previously seen lookup. Note that an implicit queryset was | ||||
|     created to traverse ``'pizzas'`` as part of the ``'pizzas__toppings'`` | ||||
|     lookup. | ||||
|  | ||||
|         >>> prefetch_related('pizza_list__toppings', Prefetch('pizzas', to_attr='pizza_list')) | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> prefetch_related("pizza_list__toppings", Prefetch("pizzas", to_attr="pizza_list")) | ||||
|  | ||||
|     This will trigger an ``AttributeError`` because ``'pizza_list'`` doesn't exist yet | ||||
|     when ``'pizza_list__toppings'`` is being processed. | ||||
| @@ -4059,12 +4094,14 @@ The ``lookup`` argument describes the relations to follow and works the same | ||||
| as the string based lookups passed to | ||||
| :meth:`~django.db.models.query.QuerySet.prefetch_related()`. For example: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> from django.db.models import Prefetch | ||||
|     >>> Question.objects.prefetch_related(Prefetch('choice_set')).get().choice_set.all() | ||||
|     >>> Question.objects.prefetch_related(Prefetch("choice_set")).get().choice_set.all() | ||||
|     <QuerySet [<Choice: Not much>, <Choice: The sky>, <Choice: Just hacking again>]> | ||||
|     # This will only execute two queries regardless of the number of Question | ||||
|     # and Choice objects. | ||||
|     >>> Question.objects.prefetch_related(Prefetch('choice_set')) | ||||
|     >>> Question.objects.prefetch_related(Prefetch("choice_set")) | ||||
|     <QuerySet [<Question: What's up?>]> | ||||
|  | ||||
| The ``queryset`` argument supplies a base ``QuerySet`` for the given lookup. | ||||
| @@ -4072,17 +4109,21 @@ This is useful to further filter down the prefetch operation, or to call | ||||
| :meth:`~django.db.models.query.QuerySet.select_related()` from the prefetched | ||||
| relation, hence reducing the number of queries even further: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> voted_choices = Choice.objects.filter(votes__gt=0) | ||||
|     >>> voted_choices | ||||
|     <QuerySet [<Choice: The sky>]> | ||||
|     >>> prefetch = Prefetch('choice_set', queryset=voted_choices) | ||||
|     >>> prefetch = Prefetch("choice_set", queryset=voted_choices) | ||||
|     >>> Question.objects.prefetch_related(prefetch).get().choice_set.all() | ||||
|     <QuerySet [<Choice: The sky>]> | ||||
|  | ||||
| The ``to_attr`` argument sets the result of the prefetch operation to a custom | ||||
| attribute: | ||||
|  | ||||
|     >>> prefetch = Prefetch('choice_set', queryset=voted_choices, to_attr='voted_choices') | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> prefetch = Prefetch("choice_set", queryset=voted_choices, to_attr="voted_choices") | ||||
|     >>> Question.objects.prefetch_related(prefetch).get().voted_choices | ||||
|     [<Choice: The sky>] | ||||
|     >>> Question.objects.prefetch_related(prefetch).get().choice_set.all() | ||||
|   | ||||
| @@ -371,12 +371,14 @@ Methods | ||||
|     Otherwise the absolute URI is built using the server variables available in | ||||
|     this request. For example: | ||||
|  | ||||
|     >>> request.build_absolute_uri() | ||||
|     'https://example.com/music/bands/the_beatles/?print=true' | ||||
|     >>> request.build_absolute_uri('/bands/') | ||||
|     'https://example.com/bands/' | ||||
|     >>> request.build_absolute_uri('https://example2.com/bands/') | ||||
|     'https://example2.com/bands/' | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> request.build_absolute_uri() | ||||
|         'https://example.com/music/bands/the_beatles/?print=true' | ||||
|         >>> request.build_absolute_uri("/bands/") | ||||
|         'https://example.com/bands/' | ||||
|         >>> request.build_absolute_uri("https://example2.com/bands/") | ||||
|         'https://example2.com/bands/' | ||||
|  | ||||
|     .. note:: | ||||
|  | ||||
| @@ -494,8 +496,10 @@ a subclass of dictionary. Exceptions are outlined here: | ||||
|  | ||||
|     Instantiates a ``QueryDict`` object based on ``query_string``. | ||||
|  | ||||
|     >>> QueryDict('a=1&a=2&c=3') | ||||
|     <QueryDict: {'a': ['1', '2'], 'c': ['3']}> | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> QueryDict("a=1&a=2&c=3") | ||||
|         <QueryDict: {'a': ['1', '2'], 'c': ['3']}> | ||||
|  | ||||
|     If ``query_string`` is not passed in, the resulting ``QueryDict`` will be | ||||
|     empty (it will have no keys or values). | ||||
|   | ||||
| @@ -498,24 +498,30 @@ If you ``pop()`` too much, it'll raise | ||||
| You can also use ``push()`` as a context manager to ensure a matching ``pop()`` | ||||
| is called. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c = Context() | ||||
|     >>> c['foo'] = 'first level' | ||||
|     >>> c["foo"] = "first level" | ||||
|     >>> with c.push(): | ||||
|     ...     c['foo'] = 'second level' | ||||
|     ...     c['foo'] | ||||
|     ...     c["foo"] = "second level" | ||||
|     ...     c["foo"] | ||||
|     ... | ||||
|     'second level' | ||||
|     >>> c['foo'] | ||||
|     >>> c["foo"] | ||||
|     'first level' | ||||
|  | ||||
| All arguments passed to ``push()`` will be passed to the ``dict`` constructor | ||||
| used to build the new context level. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c = Context() | ||||
|     >>> c['foo'] = 'first level' | ||||
|     >>> with c.push(foo='second level'): | ||||
|     ...     c['foo'] | ||||
|     >>> c["foo"] = "first level" | ||||
|     >>> with c.push(foo="second level"): | ||||
|     ...     c["foo"] | ||||
|     ... | ||||
|     'second level' | ||||
|     >>> c['foo'] | ||||
|     >>> c["foo"] | ||||
|     'first level' | ||||
|  | ||||
| .. method:: Context.update(other_dict) | ||||
| @@ -525,26 +531,31 @@ object also defines an ``update()`` method. This works like ``push()`` | ||||
| but takes a dictionary as an argument and pushes that dictionary onto | ||||
| the stack instead of an empty one. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c = Context() | ||||
|     >>> c['foo'] = 'first level' | ||||
|     >>> c.update({'foo': 'updated'}) | ||||
|     >>> c["foo"] = "first level" | ||||
|     >>> c.update({"foo": "updated"}) | ||||
|     {'foo': 'updated'} | ||||
|     >>> c['foo'] | ||||
|     >>> c["foo"] | ||||
|     'updated' | ||||
|     >>> c.pop() | ||||
|     {'foo': 'updated'} | ||||
|     >>> c['foo'] | ||||
|     >>> c["foo"] | ||||
|     'first level' | ||||
|  | ||||
| Like ``push()``, you can use ``update()`` as a context manager to ensure a | ||||
| matching ``pop()`` is called. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c = Context() | ||||
|     >>> c['foo'] = 'first level' | ||||
|     >>> with c.update({'foo': 'second level'}): | ||||
|     ...     c['foo'] | ||||
|     >>> c["foo"] = "first level" | ||||
|     >>> with c.update({"foo": "second level"}): | ||||
|     ...     c["foo"] | ||||
|     ... | ||||
|     'second level' | ||||
|     >>> c['foo'] | ||||
|     >>> c["foo"] | ||||
|     'first level' | ||||
|  | ||||
| Using a ``Context`` as a stack comes in handy in :ref:`some custom template | ||||
| @@ -555,20 +566,24 @@ tags <howto-writing-custom-template-tags>`. | ||||
| Using ``flatten()`` method you can get whole ``Context`` stack as one dictionary | ||||
| including builtin variables. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c = Context() | ||||
|     >>> c['foo'] = 'first level' | ||||
|     >>> c.update({'bar': 'second level'}) | ||||
|     >>> c["foo"] = "first level" | ||||
|     >>> c.update({"bar": "second level"}) | ||||
|     {'bar': 'second level'} | ||||
|     >>> c.flatten() | ||||
|     {'True': True, 'None': None, 'foo': 'first level', 'False': False, 'bar': 'second level'} | ||||
|  | ||||
| A ``flatten()`` method is also internally used to make ``Context`` objects comparable. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> c1 = Context() | ||||
|     >>> c1['foo'] = 'first level' | ||||
|     >>> c1['bar'] = 'second level' | ||||
|     >>> c1["foo"] = "first level" | ||||
|     >>> c1["bar"] = "second level" | ||||
|     >>> c2 = Context() | ||||
|     >>> c2.update({'bar': 'second level', 'foo': 'first level'}) | ||||
|     >>> c2.update({"bar": "second level", "foo": "first level"}) | ||||
|     {'foo': 'first level', 'bar': 'second level'} | ||||
|     >>> c1 == c2 | ||||
|     True | ||||
|   | ||||
| @@ -872,9 +872,11 @@ Accessing the cache | ||||
|     requests for the same alias in the same thread will return the same | ||||
|     object. | ||||
|  | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> from django.core.cache import caches | ||||
|         >>> cache1 = caches['myalias'] | ||||
|         >>> cache2 = caches['myalias'] | ||||
|         >>> cache1 = caches["myalias"] | ||||
|         >>> cache2 = caches["myalias"] | ||||
|         >>> cache1 is cache2 | ||||
|         True | ||||
|  | ||||
| @@ -906,11 +908,15 @@ The basic interface is: | ||||
|  | ||||
| .. method:: cache.set(key, value, timeout=DEFAULT_TIMEOUT, version=None) | ||||
|  | ||||
|     >>> cache.set('my_key', 'hello, world!', 30) | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> cache.set("my_key", "hello, world!", 30) | ||||
|  | ||||
| .. method:: cache.get(key, default=None, version=None) | ||||
|  | ||||
|     >>> cache.get('my_key') | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> cache.get("my_key") | ||||
|     'hello, world!' | ||||
|  | ||||
| ``key`` should be a ``str``, and ``value`` can be any picklable Python object. | ||||
| @@ -1100,6 +1106,8 @@ nonexistent cache key: | ||||
| You can close the connection to your cache with ``close()`` if implemented by | ||||
| the cache backend. | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> cache.close() | ||||
|  | ||||
| .. note:: | ||||
|   | ||||
| @@ -222,12 +222,14 @@ Combining multiple aggregations | ||||
| Combining multiple aggregations with ``annotate()`` will :ticket:`yield the | ||||
| wrong results <10060>` because joins are used instead of subqueries: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> book = Book.objects.first() | ||||
|     >>> book.authors.count() | ||||
|     2 | ||||
|     >>> book.store_set.count() | ||||
|     3 | ||||
|     >>> q = Book.objects.annotate(Count('authors'), Count('store')) | ||||
|     >>> q = Book.objects.annotate(Count("authors"), Count("store")) | ||||
|     >>> q[0].authors__count | ||||
|     6 | ||||
|     >>> q[0].store__count | ||||
| @@ -237,7 +239,11 @@ For most aggregates, there is no way to avoid this problem, however, the | ||||
| :class:`~django.db.models.Count` aggregate has a ``distinct`` parameter that | ||||
| may help: | ||||
|  | ||||
|     >>> q = Book.objects.annotate(Count('authors', distinct=True), Count('store', distinct=True)) | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> q = Book.objects.annotate( | ||||
|     ...     Count("authors", distinct=True), Count("store", distinct=True) | ||||
|     ... ) | ||||
|     >>> q[0].authors__count | ||||
|     2 | ||||
|     >>> q[0].store__count | ||||
| @@ -514,7 +520,9 @@ the annotation is computed over all members of the group. | ||||
| For example, consider an author query that attempts to find out the average | ||||
| rating of books written by each author: | ||||
|  | ||||
|     >>> Author.objects.annotate(average_rating=Avg('book__rating')) | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> Author.objects.annotate(average_rating=Avg("book__rating")) | ||||
|  | ||||
| This will return one result for each author in the database, annotated with | ||||
| their average book rating. | ||||
|   | ||||
| @@ -448,6 +448,8 @@ can specify the field name suffixed with ``_id``. In this case, the value | ||||
| parameter is expected to contain the raw value of the foreign model's primary | ||||
| key. For example: | ||||
|  | ||||
| .. code-block:: pycon | ||||
|  | ||||
|     >>> Entry.objects.filter(blog_id=4) | ||||
|  | ||||
| If you pass an invalid keyword argument, a lookup function will raise | ||||
| @@ -610,40 +612,42 @@ contained in a single :meth:`~django.db.models.query.QuerySet.filter` call. | ||||
|     As the second (more permissive) query chains multiple filters, it performs | ||||
|     multiple joins to the primary model, potentially yielding duplicates. | ||||
|  | ||||
|     .. code-block:: pycon | ||||
|  | ||||
|         >>> from datetime import date | ||||
|         >>> beatles = Blog.objects.create(name='Beatles Blog') | ||||
|         >>> pop = Blog.objects.create(name='Pop Music Blog') | ||||
|         >>> beatles = Blog.objects.create(name="Beatles Blog") | ||||
|         >>> pop = Blog.objects.create(name="Pop Music Blog") | ||||
|         >>> Entry.objects.create( | ||||
|         ...     blog=beatles, | ||||
|         ...     headline='New Lennon Biography', | ||||
|         ...     headline="New Lennon Biography", | ||||
|         ...     pub_date=date(2008, 6, 1), | ||||
|         ... ) | ||||
|         <Entry: New Lennon Biography> | ||||
|         >>> Entry.objects.create( | ||||
|         ...     blog=beatles, | ||||
|         ...     headline='New Lennon Biography in Paperback', | ||||
|         ...     headline="New Lennon Biography in Paperback", | ||||
|         ...     pub_date=date(2009, 6, 1), | ||||
|         ... ) | ||||
|         <Entry: New Lennon Biography in Paperback> | ||||
|         >>> Entry.objects.create( | ||||
|         ...     blog=pop, | ||||
|         ...     headline='Best Albums of 2008', | ||||
|         ...     headline="Best Albums of 2008", | ||||
|         ...     pub_date=date(2008, 12, 15), | ||||
|         ... ) | ||||
|         <Entry: Best Albums of 2008> | ||||
|         >>> Entry.objects.create( | ||||
|         ...     blog=pop, | ||||
|         ...     headline='Lennon Would Have Loved Hip Hop', | ||||
|         ...     headline="Lennon Would Have Loved Hip Hop", | ||||
|         ...     pub_date=date(2020, 4, 1), | ||||
|         ... ) | ||||
|         <Entry: Lennon Would Have Loved Hip Hop> | ||||
|         >>> Blog.objects.filter( | ||||
|         ...     entry__headline__contains='Lennon', | ||||
|         ...     entry__headline__contains="Lennon", | ||||
|         ...     entry__pub_date__year=2008, | ||||
|         ... ) | ||||
|         <QuerySet [<Blog: Beatles Blog>]> | ||||
|         >>> Blog.objects.filter( | ||||
|         ...     entry__headline__contains='Lennon', | ||||
|         ...     entry__headline__contains="Lennon", | ||||
|         ... ).filter( | ||||
|         ...     entry__pub_date__year=2008, | ||||
|         ... ) | ||||
|   | ||||
		Reference in New Issue
	
	Block a user