dict2colander
=============
*Convert python dict (YAML, JSON) to colander schema.*
`Colander <http://docs.pylonsproject.org/projects/colander/en/latest/>`_
is library, which enables you to validate and convert YAML, JSON
and HTML form data. Colander schema as it is could be defined only
in Python declaratively for example like this:
.. code-block:: python
import colander
class Person(colander.MappingSchema):
name = colander.SchemaNode(colander.String())
age = colander.SchemaNode(colander.Int(),
validator=colander.Range(0, 200))
@colander.instantiate()
class phones(colander.SequenceSchema):
@colander.instantiate()
class phone(colander.MappingSchema):
location = colander.SchemaNode(colander.String(),
validator=colander.OneOf(['home', 'work']))
number = colander.SchemaNode(colander.String())
With dict2colander you can define the same colander schema in
dictionary and convert it to colader.MappingSchema object.
Instalation
-----------
You can install dict2colander from
`Python Package Index <https://pypi.python.org/pypi/dict2colander/0.1>`_
like this:
.. code-block:: shell
pip install dict2colander
Usage
-----
.. code-block:: python
from dict2colander import dict2colander
schema_dict = {
'type': 'Mapping',
'name': 'person',
'subnodes': [
{'type': 'String', 'name': 'name'},
{'type': 'Integer', 'name': 'age',
'validators':
{'Range': {'args': ('0', '200')}}},
{'type': 'Sequence',
'name': 'phones',
'subnodes': [
{'type': 'Mapping', 'name': 'phone',
'subnodes': [
{'type': 'String', 'name': 'location',
'validators':
{'OneOf': {'args': (['home', 'work'],)}}},
{'type': 'String', 'name': 'number'}
]}]},
]
}
schema = dict2colander(schema_dict)
data = {
'name': 'keith',
'age': '20',
'friends':[('1', 'jim'),('2', 'bob'), ('3', 'joe'), ('4', 'fred')],
'phones':[{'location':'home', 'number':'555-1212'},
{'location':'work', 'number':'555-8989'},],
}
serialized_data = schema.deserialize(data)
print serialized_data
Dict2colander is intended to make possible to read colander schemas
from YAML or JSON format. So here is schema from previous example
written in YAML:
.. code-block:: yaml
---
name: person
type: Mapping
subnodes:
- name: name
type: String
- name: age
type: Integer
validators:
Range:
args: ['0', '200']
- name: phones
type: Sequence
subnodes:
- name: phone
type: Mapping
subnodes:
- name: location
type: String
validators:
OneOf:
args: [[home, work]]
- name: number
type: String
Note that *Range* validator has arguments defined as *Strings* not
*Integers* although that field *age* is of type *Integer*.
Here are data to deserialize in YAML format from first example:
.. code-block:: yaml
---
name: keith
age: 20
friends:
- [1, jim]
- [2, bob]
- [3, joe]
- [4, fred]
phones:
- location: home
number: 555-1212
- location: work
number: 555-8989
Here is example how YAML data are deserialized with schema defined
in YAML document.
.. code-block:: python
import yaml
import dict2colander
def deserialize(yaml_doc, yaml_schema):
mapping_schema = dict2colander.dict2colander(yaml_schema)
return mapping_schema.deserialize(yaml_doc)
f = open('doc.yaml')
doc = yaml.load(f)
f.close()
f = open('schema.yaml')
schema = yaml.load(f)
f.close()
dict_doc = deserialize(doc, schema)
print dict_doc
