Add colander.Set type, ported from deform.Set
Add Python 3.3 to tox configuration and use newer tox testing regime (setup.py dev).
Add Python 3.3 Trove classifier.
Calling bind on a schema node e.g. cloned_node = somenode.bind(a=1, b=2) on a schema node now results in the cloned node having a bindings attribute of the value {'a':1, 'b':2}.
It is no longer necessary to pass a typ argument to a SchemaNode constructor if the node class has a schema_type callable as a class attribute which, when called with no arguments, returns a schema type. This callable will be called to obtain the schema type if a typ is not supplied to the constructor. The default SchemaNode object’s schema_type callable raises a NotImplementedError when it is called.
SchemaNode now has a raise_invalid method which accepts a message and raises a colander.Invalid exception using self as the node and the message as its message.
It is now possible and advisable to subclass SchemaNode in order to create a bundle of default node behavior. The subclass can define the following methods and attributes: preparer, validator, default, missing, name, title, description, widget, and after_bind.
For example, the older, more imperative style that looked like this still works, of course:
from colander import SchemaNode
ranged_int = colander.SchemaNode(
validator=colander.Range(0, 10),
default = 10,
title='Ranged Int'
)
But you can alternately now do something like this:
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
validator = colander.Range(0, 10)
default = 10
title = 'Ranged Int'
ranged_int = RangedInt()
Values that are expected to be callables can now alternately be methods of the schemanode subclass instead of plain attributes:
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
default = 10
title = 'Ranged Int'
def validator(self, node, cstruct):
if not 0 < cstruct < 10:
raise colander.Invalid(node, 'Must be between 0 and 10')
ranged_int = RangedInt()
Note that when implementing a method value such as validator that expects to receive a node argument, node must be provided in the call signature, even though node will almost always be the same as self. This is because Colander simply treats the method as another kind of callable, be it a method, or a function, or an instance that has a __call__ method. It doesn’t care that it happens to be a method of self, and it needs to support callables that are not methods, so it sends node in regardless.
You can’t currently use method definitions as colander.deferred callables. For example this will not work:
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
default = 10
title = 'Ranged Int'
@colander.deferred
def validator(self, node, kw):
request = kw['request']
def avalidator(node, cstruct):
if not 0 < cstruct < 10:
if request.user != 'admin':
raise colander.Invalid(node, 'Must be between 0 and 10')
return avalidator
ranged_int = RangedInt()
bound_ranged_int = ranged_int.bind(request=request)
This will result in:
TypeError: avalidator() takes exactly 3 arguments (2 given)
However, if you treat the thing being decorated as a function instead of a method (remove the self argument from the argument list), it will indeed work):
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
default = 10
title = 'Ranged Int'
@colander.deferred
def validator(node, kw):
request = kw['request']
def avalidator(node, cstruct):
if not 0 < cstruct < 10:
if request.user != 'admin':
raise colander.Invalid(node, 'Must be between 0 and 10')
return avalidator
ranged_int = RangedInt()
bound_ranged_int = ranged_int.bind(request=request)
In previous releases of Colander, the only way to defer the computation of values was via the colander.deferred decorator. In this release, however, you can instead use the bindings attribute of self to obtain access to the bind parameters within values that are plain old methods:
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
default = 10
title = 'Ranged Int'
def validator(self, node, cstruct):
request = self.bindings['request']
if not 0 < cstruct < 10:
if request.user != 'admin':
raise colander.Invalid(node, 'Must be between 0 and 10')
ranged_int = RangedInt()
bound_range_int = ranged_int.bind(request=request)
If the things you’re trying to defer aren’t callables like validator, but they’re instead just plain attributes like missing or default, instead of using a colander.deferred, you can use after_bind to set attributes of the schemanode that rely on binding variables:
from colander import SchemaNode
class UserIdSchemaNode(SchemaNode):
title = 'User Id'
def after_bind(self, node, kw):
self.default = kw['request'].user.id
You can override the default values of a schemanode subclass in its constructor:
from colander import SchemaNode
class RangedIntSchemaNode(SchemaNode):
default = 10
title = 'Ranged Int'
validator = colander.Range(0, 10)
ranged_int = RangedInt(validator=colander.Range(0, 20))
In the above example, the validation will be done on 0-20, not 0-10.
If a schema node name conflicts with a schema value attribute name on the same class, you can work around it by giving the schema node a bogus name in the class definition but providing a correct name argument to the schema node constructor:
from colander import SchemaNode, Schema
class SomeSchema(Schema):
title = 'Some Schema'
thisnamewillbeignored = colander.SchemaNode(
colander.String(),
name='title'
)
Note that such a workaround is only required if the conflicting names are attached to the exact same class definition. Colander scrapes off schema node definitions at each class’ construction time, so it’s not an issue for inherited values. For example:
from colander import SchemaNode, Schema
class SomeSchema(Schema):
title = colander.SchemaNode(colander.String())
class AnotherSchema(SomeSchema):
title = 'Some Schema'
schema = AnotherSchema()
In the above example, even though the title = 'Some Schema' appears to override the superclass’ title SchemaNode, a title SchemaNode will indeed be present in the child list of the schema instance (schema['title'] will return the title SchemaNode) and the schema’s title attribute will be Some Schema (schema.title will return Some Schema).
Normal inheritance rules apply to class attributes and methods defined in a schemanode subclass. If your schemanode subclass inherits from another schemanode class, your schemanode subclass’ methods and class attributes will override the superclass’ methods and class attributes.
Ordering of child schema nodes when inheritance is used works like this: the “deepest” SchemaNode class in the MRO of the inheritance chain is consulted first for nodes, then the next deepest, then the next, and so on. So the deepest class’ nodes come first in the relative ordering of schema nodes, then the next deepest, and so on. For example:
class One(colander.Schema):
a = colander.SchemaNode(
colander.String(),
id='a1',
)
b = colander.SchemaNode(
colander.String(),
id='b1',
)
d = colander.SchemaNode(
colander.String(),
id='d1',
)
class Two(One):
a = colander.SchemaNode(
colander.String(),
id='a2',
)
c = colander.SchemaNode(
colander.String(),
id='c2',
)
e = colander.SchemaNode(
colander.String(),
id='e2',
)
class Three(Two):
b = colander.SchemaNode(
colander.String(),
id='b3',
)
d = colander.SchemaNode(
colander.String(),
id='d3',
)
f = colander.SchemaNode(
colander.String(),
id='f3',
)
three = Three()
The ordering of child nodes computed in the schema node three will be ['a2', 'b3', 'd3', 'c2', 'e2', 'f3']. The ordering starts a1, b1, d1 because that’s the ordering of nodes in One, and One is the deepest SchemaNode in the inheritance hierarchy. Then it processes the nodes attached to Two, the next deepest, which causes a1 to be replaced by a2, and c2 and e2 to be appended to the node list. Then finally it processes the nodes attached to Three, which causes b1 to be replaced by b3, and d1 to be replaced by d3, then finally f is appended.
Multiple inheritance works the same way:
class One(colander.Schema):
a = colander.SchemaNode(
colander.String(),
id='a1',
)
b = colander.SchemaNode(
colander.String(),
id='b1',
)
d = colander.SchemaNode(
colander.String(),
id='d1',
)
class Two(colander.Schema):
a = colander.SchemaNode(
colander.String(),
id='a2',
)
c = colander.SchemaNode(
colander.String(),
id='c2',
)
e = colander.SchemaNode(
colander.String(),
id='e2',
)
class Three(Two, One):
b = colander.SchemaNode(
colander.String(),
id='b3',
)
d = colander.SchemaNode(
colander.String(),
id='d3',
)
f = colander.SchemaNode(
colander.String(),
id='f3',
)
three = Three()
The resulting node ordering of three is the same as the single inheritance example: ['a2', 'b3', 'd3', 'c2', 'e2', 'f3'] due to the MRO deepest-first ordering (One, then Two, then Three).
A release centered around normalizing the treatment of default and missing values.
missing constructor arg to SchemaNode: signifies deserialization default, disambiguated from default which acted as both serialization and deserialization default previously.
Changes necessitated / made possible by SchemaNode missing addition:
New concept: colander.null input to serialization and deserialization. Use of colander.null normalizes serialization and deserialization default handling.
Changes necessitated / made possible by colander.null addition:
been removed; all serializations are partial, and partial deserializations are not necessary.
serializations instead of omitting missing node values from the cstruct.
deserialized data structures.
sdefault attribute of SchemaNode has been removed; we never need to serialize a default anymore.
The value colander.null will be passed as appstruct to each type’s serialize method when a mapping appstruct doesn’t have a corresponding key instead of None, as was the practice previously.
The value colander.null will be passed as cstruct to each type’s deserialize method when a mapping cstruct doesn’t have a corresponding key instead of None, as was the practice previously.
Types now must handle colander.null explicitly during serialization.
Updated and expanded documentation, particularly with respect to new colander.null handling.
The value argument`` to the serialize method of a SchemaNode is now named appstruct. It is no longer a required argument; it defaults to colander.null now.
The value argument to the deserialize method of a SchemaNode is now named cstruct. It is no longer a required argument; it defaults to colander.null now.
The value argument to the serialize method of each built-in type is now named appstruct, and is now required: it is no longer a keyword argument that has a default.
The value argument to the deserialize method of each built-in type is now named cstruct, and is now required: it is no longer a keyword argument that has a default.