From a03b356e28ce890c15883f5d19ca6dba3500c462 Mon Sep 17 00:00:00 2001
From: Anes Foufa <anes.foufa@upply.com>
Date: Tue, 28 Jul 2020 16:52:54 +0200
Subject: [PATCH] feat: FloatField optionally validates that the number is no
 greater than or equals a given value.

---
 docs/api-guide/fields.md     |  3 ++-
 rest_framework/fields.py     | 15 +++++++++++----
 rest_framework/validators.py |  9 +++++++++
 tests/test_fields.py         | 20 ++++++++++++++++++++
 4 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/docs/api-guide/fields.md b/docs/api-guide/fields.md
index 7722a1f27..c7a02bbb7 100644
--- a/docs/api-guide/fields.md
+++ b/docs/api-guide/fields.md
@@ -276,10 +276,11 @@ A floating point representation.
 
 Corresponds to `django.db.models.fields.FloatField`.
 
-**Signature**: `FloatField(max_value=None, min_value=None)`
+**Signature**: `FloatField(max_value=None, min_value=None, exclusive_min=False)`
 
 - `max_value` Validate that the number provided is no greater than this value.
 - `min_value` Validate that the number provided is no less than this value.
+- `exclusive_min` If true, validate that the number provided is no greater than or equals `min_value`.
 
 ## DecimalField
 
diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index da2dd54be..dd1cadc9b 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -38,7 +38,7 @@ from rest_framework.exceptions import ErrorDetail, ValidationError
 from rest_framework.settings import api_settings
 from rest_framework.utils import html, humanize_datetime, json, representation
 from rest_framework.utils.formatting import lazy_format
-from rest_framework.validators import ProhibitSurrogateCharactersValidator
+from rest_framework.validators import ExclusiveLMinValueValidator, ProhibitSurrogateCharactersValidator
 
 
 class empty:
@@ -968,6 +968,7 @@ class FloatField(Field):
         'invalid': _('A valid number is required.'),
         'max_value': _('Ensure this value is less than or equal to {max_value}.'),
         'min_value': _('Ensure this value is greater than or equal to {min_value}.'),
+        'exclusive_min_value': _('Ensure this value is greater than {min_value}.'),
         'max_string_length': _('String value too large.')
     }
     MAX_STRING_LENGTH = 1000  # Guard against malicious string inputs.
@@ -975,15 +976,21 @@ class FloatField(Field):
     def __init__(self, **kwargs):
         self.max_value = kwargs.pop('max_value', None)
         self.min_value = kwargs.pop('min_value', None)
+        self.exclusive_min = kwargs.pop("exclusive_min", False)
         super().__init__(**kwargs)
         if self.max_value is not None:
             message = lazy_format(self.error_messages['max_value'], max_value=self.max_value)
             self.validators.append(
                 MaxValueValidator(self.max_value, message=message))
         if self.min_value is not None:
-            message = lazy_format(self.error_messages['min_value'], min_value=self.min_value)
-            self.validators.append(
-                MinValueValidator(self.min_value, message=message))
+            if self.exclusive_min:
+                message = lazy_format(self.error_messages["exclusive_min_value"], min_value=self.min_value)
+                self.validators.append(
+                    ExclusiveLMinValueValidator(self.min_value, message=message))
+            else:
+                message = lazy_format(self.error_messages['min_value'], min_value=self.min_value)
+                self.validators.append(
+                    MinValueValidator(self.min_value, message=message))
 
     def to_internal_value(self, data):
 
diff --git a/rest_framework/validators.py b/rest_framework/validators.py
index a5cb75a84..1cae3cb67 100644
--- a/rest_framework/validators.py
+++ b/rest_framework/validators.py
@@ -6,6 +6,7 @@ This gives us better separation of concerns, allows us to use single-step
 object creation, and makes it possible to switch between using the implicit
 `ModelSerializer` class and an equivalent explicit `Serializer` class.
 """
+from django.core.validators import BaseValidator
 from django.db import DataError
 from django.utils.translation import gettext_lazy as _
 
@@ -278,3 +279,11 @@ class UniqueForYearValidator(BaseUniqueForValidator):
         filter_kwargs[field_name] = value
         filter_kwargs['%s__year' % date_field_name] = date.year
         return qs_filter(queryset, **filter_kwargs)
+
+
+class ExclusiveLMinValueValidator(BaseValidator):
+    message = _('Ensure this value is greater than %(limit_value)s.')
+    code = "exclusive_min_value"
+
+    def compare(self, a, b):
+        return a <= b
diff --git a/tests/test_fields.py b/tests/test_fields.py
index b1ad1dc66..0e2f787b6 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -1076,6 +1076,26 @@ class TestMinMaxFloatField(FieldValues):
     field = serializers.FloatField(min_value=1, max_value=3)
 
 
+class TestExclusiveMinFloatField(FieldValues):
+    """
+    Valid and invalid values for 'FloatField' with exclusive_min limits.
+    """
+    valid_inputs = {
+        '1.01': 1.01,
+        '3': 3,
+        1.01: 1.01,
+        3: 3,
+        3.0: 3.0,
+    }
+    invalid_inputs = {
+        1: ['Ensure this value is greater than 1.'],
+        '1': ['Ensure this value is greater than 1.'],
+        '1.0': ['Ensure this value is greater than 1.'],
+    }
+    outputs = {}
+    field = serializers.FloatField(min_value=1, exclusive_min=True)
+
+
 class TestDecimalField(FieldValues):
     """
     Valid and invalid values for `DecimalField`.