Dicts

Todo

intro

set() Policy

Todo

strict, duck, etc.

Validation

If descent_validators is defined, these validators will be run first, before member elements are validated.

If validators is defined, these validators will be run after member elements are validated.

Dict

class Dict(value=Unspecified, **kw)

Bases: flatland.schema.containers.Mapping, dict

A mapping Container with named members.

policy = 'subset'

Deprecated. One of ‘strict’, ‘subset’ or ‘duck’. Default ‘subset’.

Operates as SetWithAllFields and SetWithKnownFields, except raises an exception immediately upon set().

To migrate to the new validators, set policy to None to disable the policy behavior.

of(*fields)

Todo

doc of()

classmethod from_object(obj, include=None, omit=None, rename=None, **kw)

Return an element initialized with an object’s attributes.

Parameters:

• obj – any object
• include – optional, an iterable of attribute names to pull from obj, if present on the object. Only these attributes will be included.
• omit – optional, an iterable of attribute names to ignore on obj. All other attributes matching a named field on the mapping will be included.
• rename – optional, a mapping of attribute-to-field name transformations. Attributes specified in the mapping will be included regardless of include or omit.
• **kw – keyword arguments will be passed to the element’s constructor.

include and omit are mutually exclusive.

This is a convenience constructor for set_by_object():

element = cls(**kw)
element.set_by_object(obj, include, omit, rename)

set(value, policy=None)

Todo

doc set()

set_by_object(obj, include=None, omit=None, rename=None)

Set fields with an object’s attributes.

Parameters:

• obj – any object
• include – optional, an iterable of attribute names to pull from obj, if present on the object. Only these attributes will be included.
• omit – optional, an iterable of attribute names to ignore on obj. All other attributes matching a named field on the mapping will be included.
• rename – optional, a mapping of attribute-to-field name transformations. Attributes specified in the mapping will be included regardless of include or omit.

include and omit are mutually exclusive.

Sets fields on self, using as many attributes as possible from obj. Object attributes that do not correspond to field names are ignored.

Mapping instances have two corresponding methods useful for round-tripping values in and out of your domain objects.

update_object() performs the inverse of set_object(), and slice() is useful for constructing new objects.

>>> user = User('biff', 'secret')
>>> form = UserForm()
>>> form.set_by_object(user)
>>> form['login'].value
u'biff'
>>> form['password'] = u'new-password'
>>> form.update_object(user, omit=['verify_password'])
>>> user.password
u'new-password'
>>> user_keywords = form.slice(omit=['verify_password'], key=str)
>>> sorted(user_keywords.keys())
['login', 'password']
>>> new_user = User(**user_keywords)

update_object(obj, include=None, omit=None, rename=None, key=<function identifier_transform>)

Update an object’s attributes using the element’s values.

Produces a slice() using include, omit, rename and key, and sets the selected attributes on obj using setattr.

Returns:nothing. obj is modified directly.

slice(include=None, omit=None, rename=None, key=None)

Return a dict containing a subset of the element’s values.

SparseDict

class SparseDict(value=Unspecified, **kw)

Bases: flatland.schema.containers.Dict

A Mapping which may contain a subset of the schema’s allowed keys.

This differs from Dict in that new instances are not created with empty values for all possible keys. In addition, mutating operations are allowed so long as the operations operate within the schema. For example, you may pop() and del members of the mapping.

minimum_fields = None

The subset of fields to autovivify on instantiation.

May be None or 'required'. If None, mappings will be created empty and mutation operations are unrestricted within the bounds of the field_schema. If required, fields with optional of False will always be present after instantiation, and attempts to remove them from the mapping with del and friends will raise TypeError.

may_contain(key)

Return True if the element schema allows a field named key.

clear() → None. Remove all items from D.

popitem() → (k, v), remove and return some (key, value) pair as a

2-tuple; but raise KeyError if D is empty.

pop(k[, d]) → v, remove specified key and return the corresponding value.

If key is not found, d is returned if given, otherwise KeyError is raised

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D

set_default()

set() the element to the schema default.