1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
Custom `class Meta <marshmallow.Schema.Meta>` options
=====================================================
`class Meta <marshmallow.Schema.Meta>` options are a way to configure and modify a `Schema's <Schema>` behavior. See `marshmallow.Schema.Meta` for a listing of available options.
You can add custom `class Meta <marshmallow.Schema.Meta>` options by subclassing `marshmallow.SchemaOpts`.
Example: Enveloping, revisited
------------------------------
Let's build upon the :ref:`previous enveloping implementation <enveloping_1>` above for adding an envelope to serialized output.
This time, we will allow the envelope key to be customizable with `class Meta <marshmallow.Schema.Meta>` options.
::
# Example outputs
{
'user': {
'name': 'Keith',
'email': 'keith@stones.com'
}
}
# List output
{
'users': [{'name': 'Keith'}, {'name': 'Mick'}]
}
First, we'll add our namespace configuration to a custom options class.
.. code-block:: python
from marshmallow import Schema, SchemaOpts
class NamespaceOpts(SchemaOpts):
"""Same as the default class Meta options, but adds "name" and
"plural_name" options for enveloping.
"""
def __init__(self, meta, **kwargs):
SchemaOpts.__init__(self, meta, **kwargs)
self.name = getattr(meta, "name", None)
self.plural_name = getattr(meta, "plural_name", self.name)
Then we create a custom :class:`Schema` that uses our options class.
.. code-block:: python
class NamespacedSchema(Schema):
OPTIONS_CLASS = NamespaceOpts
@pre_load(pass_many=True)
def unwrap_envelope(self, data, many, **kwargs):
key = self.opts.plural_name if many else self.opts.name
return data[key]
@post_dump(pass_many=True)
def wrap_with_envelope(self, data, many, **kwargs):
key = self.opts.plural_name if many else self.opts.name
return {key: data}
Our application schemas can now inherit from our custom schema class.
.. code-block:: python
class UserSchema(NamespacedSchema):
name = fields.String()
email = fields.Email()
class Meta:
name = "user"
plural_name = "users"
ser = UserSchema()
user = User("Keith", email="keith@stones.com")
result = ser.dump(user)
result # {"user": {"name": "Keith", "email": "keith@stones.com"}}
|
