add `ConstrainedFloat, confloat, PositiveFloat and NegativeFloat` types #166 (#166)

HISTORY.rst

@@ -8,6 +8,7 @@ v0.8.1 (2018-XX-XX)
 * tweak email-validator import error message #145
 * fix parse error of parse_date() and parse_datetime() when input is 0 #144
 * add ``Config.anystr_strip_whitespace`` and ``strip_whitespace`` kwarg to ``constr``, by default values is `False` #163
+* add ``ConstrainedFloat``, ``confloat``, ``PositiveFloat`` and ``NegativeFloat`` types #166
 
 v0.8.0 (2018-03-25)
 ...................

docs/examples/exotic.py

@@ -1,8 +1,8 @@
 from pathlib import Path
 from uuid import UUID
 
-from pydantic import (DSN, BaseModel, EmailStr, NameEmail, PyObject, conint,
-                      constr, PositiveInt, NegativeInt)
+from pydantic import (DSN, BaseModel, EmailStr, NameEmail, NegativeFloat, NegativeInt, PositiveFloat, PositiveInt,
+                      PyObject, confloat, conint, constr)
 
 
 class Model(BaseModel):
@@ -17,6 +17,10 @@ class Model(BaseModel):
     pos_int: PositiveInt = None
     neg_int: NegativeInt = None
 
+    big_float: confloat(gt=1000, lt=1024) = None
+    pos_float: PositiveFloat = None
+    neg_float: NegativeFloat = None
+
     email_address: EmailStr = None
     email_and_name: NameEmail = None
 
@@ -39,6 +43,9 @@ m = Model(
     big_int=1001,
     pos_int=1,
     neg_int=-1,
+    big_float=1002.1,
+    pos_float=2.2,
+    neg_float=-2.3,
     email_address='Samuel Colvin <s@muelcolvin.com >',
     email_and_name='Samuel Colvin <s@muelcolvin.com >',
     uuid='ebcdab58-6eb8-46fb-a190-d07a33e9eac8'
@@ -54,6 +61,9 @@ print(m.dict())
     'big_int': 1001,
     'pos_int': 1,
     'neg_int': -1,
+    'big_float': 1002.1,
+    'pos_float': 2.2,
+    'neg_float': -2.3,
     'email_address': 's@muelcolvin.com',
     'email_and_name': <NameEmail("Samuel Colvin <s@muelcolvin.com>")>,
     ...

pydantic/types.py

@@ -25,6 +25,10 @@ __all__ = [
     'conint',
     'PositiveInt',
     'NegativeInt',
+    'ConstrainedFloat',
+    'confloat',
+    'PositiveFloat',
+    'NegativeFloat',
 ]
 
 NoneStr = Optional[str]
@@ -201,4 +205,36 @@ class NegativeInt(ConstrainedInt):
     lt = 0
 
 
+class ConstrainedFloat(float):
+    gt: Union[int, float] = None
+    lt: Union[int, float] = None
+
+    @classmethod
+    def get_validators(cls):
+        yield float
+        yield cls.validate
+
+    @classmethod
+    def validate(cls, value: float) -> float:
+        if cls.gt is not None and value <= cls.gt:
+            raise ValueError(f'size less than minimum allowed: {cls.gt}')
+        elif cls.lt is not None and value >= cls.lt:
+            raise ValueError(f'size greater than maximum allowed: {cls.lt}')
+        return value
+
+
+def confloat(*, gt=None, lt=None) -> Type[float]:
+    # use kwargs then define conf in a dict to aid with IDE type hinting
+    namespace = dict(gt=gt, lt=lt)
+    return type('ConstrainedFloatValue', (ConstrainedFloat,), namespace)
+
+
+class PositiveFloat(ConstrainedFloat):
+    gt = 0
+
+
+class NegativeFloat(ConstrainedFloat):
+    lt = 0
+
+
 # TODO, JsonEither, JsonList, JsonDict

tests/test_types.py

@@ -6,8 +6,8 @@ from uuid import UUID
 
 import pytest
 
-from pydantic import (DSN, BaseModel, EmailStr, NameEmail, NegativeInt, PositiveInt, PyObject, StrictStr,
-                      ValidationError, conint, constr)
+from pydantic import (DSN, BaseModel, EmailStr, NameEmail, NegativeFloat, NegativeInt, PositiveFloat, PositiveInt,
+                      PyObject, StrictStr, ValidationError, confloat, conint, constr)
 
 try:
     import email_validator
@@ -410,6 +410,20 @@ def test_int_validation():
     assert exc_info.value.message == '3 errors validating input'
 
 
+class FloatModel(BaseModel):
+    a: PositiveFloat = None
+    b: NegativeFloat = None
+    c: confloat(gt=4, lt=12.2) = None
+
+
+def test_float_validation():
+    m = FloatModel(a=5.1, b=-5.2, c=5.3)
+    assert m == {'a': 5.1, 'b': -5.2, 'c': 5.3}
+    with pytest.raises(ValidationError) as exc_info:
+        FloatModel(a=-5.1, b=5.2, c=-5.3)
+    assert exc_info.value.message == '3 errors validating input'
+
+
 def test_set():
     class SetModel(BaseModel):
         v: set = ...