Validation and parsing library
Project description
Trafaret
Ultimate transformation library that supports validation, contexts and aiohttp.
Trafaret is rigid and powerful lib to work with foreign data, configs etc. It provides simple way to check anything, and convert it accordingly to your needs.
It has shortcut syntax and ability to express anything that you can code:
>>> from trafaret.constructor import construct
>>> validator = construct({'a': int, 'b': [str]})
>>> validator({'a': 5, 'b': ['lorem', 'ipsum']})
{'a': 5, 'b': ['lorem', 'ipsum']}
>>> validator({'a': 5, 'b': ['gorky', 9]})
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/mkrivushin/w/trafaret/trafaret/__init__.py", line 204, in __call__
return self.check(val)
File "/Users/mkrivushin/w/trafaret/trafaret/__init__.py", line 144, in check
return self._convert(self.check_and_return(value))
File "/Users/mkrivushin/w/trafaret/trafaret/__init__.py", line 1105, in check_and_return
raise DataError(error=errors, trafaret=self)
trafaret.DataError: {'b': DataError({1: DataError(value is not a string)})}Read The Docs hosted documentation http://trafaret.readthedocs.org/en/latest/ or look to the docs/intro.rst for start.
Trafaret can even generate Trafarets instances to build transformators from json, like in json schema implementation Trafaret Schema
New
2.0.2
construct for int and float will use ToInt and ToFloat
2.0.0
WithRepr – use it to return custom representation, like <Email>
Strip a lot from dict, like keys()
Trafarets are not mutable
DataError has new code attribute, self.failure has code argument
OnError has code argument too
New DataError.to_struct method that returns errors in more consistent way
String, AnyString, Bytes, FromBytes(encoding=utf-8)
Int, ToInt, Float, ToFloat
ToDecimal
Iterable that acts like a List, but works with any iterable
New Date, ToDate and DateTime, ToDateTime trafarets
StrBool trafaret renamed to ToBool
Visitor trafaret was deleted
Test coverage
1.x.x
converters and convert=False are deleted in favor of And and &
String parameter regex deleted in favor of Regexp and RegexpRaw usage
new OnError to customize error message
context=something argument for __call__ and check Trafaret methods. Supported by Or, And, Forward etc.
new customizable method transform like change_and_return but takes context= arg
new trafaret_instance.async_check method that works with await
Doc
For simple example what can be done:
import datetime
import trafaret as t
date = t.Dict(year=t.Int, month=t.Int, day=t.Int) >> (lambda d: datetime.datetime(**d))
assert date.check({'year': 2012, 'month': 1, 'day': 12}) == datetime.datetime(2012, 1, 12)Work with regex:
>>> c = t.RegexpRaw(r'^name=(\w+)$') >> (lambda m: m.group(1))
>>> c.check('name=Jeff')
'Jeff'Rename dict keys:
>>> c = t.Dict({(t.Key('uNJ') >> 'user_name'): t.String})
>>> c.check({'uNJ': 'Adam'})
{'user_name': 'Adam'}Arrow date checking:
import arrow
def check_datetime(str):
try:
return arrow.get(str).naive
except arrow.parser.ParserError:
return t.DataError('value is not in proper date/time format')Yes, you can write trafarets that simple.
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