From e21156ff17f88ae4892045580b47a47b66d45331 Mon Sep 17 00:00:00 2001
From: Clinton Blackburn <clinton.blackburn@gmail.com>
Date: Sat, 4 Apr 2020 16:17:55 -0700
Subject: [PATCH] Corrected OpenAPI schema type for DecimalField

The API renders DecimalFields as strings. The generated schema now renders decimal fields correctly as strings.

Fixes #7253
---
 rest_framework/schemas/openapi.py | 30 +++++++-----------------------
 tests/schemas/test_openapi.py     |  8 ++------
 2 files changed, 9 insertions(+), 29 deletions(-)

diff --git a/rest_framework/schemas/openapi.py b/rest_framework/schemas/openapi.py
index 1d0ec35d5..88f4db08c 100644
--- a/rest_framework/schemas/openapi.py
+++ b/rest_framework/schemas/openapi.py
@@ -6,8 +6,8 @@ from operator import attrgetter
 from urllib.parse import urljoin
 
 from django.core.validators import (
-    DecimalValidator, EmailValidator, MaxLengthValidator, MaxValueValidator,
-    MinLengthValidator, MinValueValidator, RegexValidator, URLValidator
+    EmailValidator, MaxLengthValidator, MaxValueValidator, MinLengthValidator,
+    MinValueValidator, RegexValidator, URLValidator
 )
 from django.db import models
 from django.utils.encoding import force_str
@@ -329,10 +329,10 @@ class AutoSchema(ViewInspector):
             type = 'boolean'
         elif all(isinstance(choice, int) for choice in choices):
             type = 'integer'
-        elif all(isinstance(choice, (int, float, Decimal)) for choice in choices):  # `number` includes `integer`
+        elif all(isinstance(choice, (int, float)) for choice in choices):  # `number` includes `integer`
             # Ref: https://tools.ietf.org/html/draft-wright-json-schema-validation-00#section-5.21
             type = 'number'
-        elif all(isinstance(choice, str) for choice in choices):
+        elif all(isinstance(choice, (str, Decimal)) for choice in choices):
             type = 'string'
         else:
             type = None
@@ -442,18 +442,11 @@ class AutoSchema(ViewInspector):
                 content['format'] = field.protocol
             return content
 
-        # DecimalField has multipleOf based on decimal_places
         if isinstance(field, serializers.DecimalField):
-            content = {
-                'type': 'number'
+            return {
+                'type': 'string',
+                'format': 'decimal'
             }
-            if field.decimal_places:
-                content['multipleOf'] = float('.' + (field.decimal_places - 1) * '0' + '1')
-            if field.max_whole_digits:
-                content['maximum'] = int(field.max_whole_digits * '9') + 1
-                content['minimum'] = -content['maximum']
-            self._map_min_max(field, content)
-            return content
 
         if isinstance(field, serializers.FloatField):
             content = {
@@ -556,15 +549,6 @@ class AutoSchema(ViewInspector):
                 schema['maximum'] = v.limit_value
             elif isinstance(v, MinValueValidator):
                 schema['minimum'] = v.limit_value
-            elif isinstance(v, DecimalValidator):
-                if v.decimal_places:
-                    schema['multipleOf'] = float('.' + (v.decimal_places - 1) * '0' + '1')
-                if v.max_digits:
-                    digits = v.max_digits
-                    if v.decimal_places is not None and v.decimal_places > 0:
-                        digits -= v.decimal_places
-                    schema['maximum'] = int(digits * '9') + 1
-                    schema['minimum'] = -schema['maximum']
 
     def _get_paginator(self):
         pagination_class = getattr(self.view, 'pagination_class', None)
diff --git a/tests/schemas/test_openapi.py b/tests/schemas/test_openapi.py
index c9f6d967e..604dd7ffa 100644
--- a/tests/schemas/test_openapi.py
+++ b/tests/schemas/test_openapi.py
@@ -830,13 +830,9 @@ class TestOperationIntrospection(TestCase):
         assert properties['regex']['pattern'] == r'[ABC]12{3}'
         assert properties['regex']['description'] == 'must have an A, B, or C followed by 1222'
 
-        assert properties['decimal1']['type'] == 'number'
-        assert properties['decimal1']['multipleOf'] == .01
-        assert properties['decimal1']['maximum'] == 10000
-        assert properties['decimal1']['minimum'] == -10000
+        assert properties['decimal1'] == {'type': 'string', 'format': 'decimal'}
 
-        assert properties['decimal2']['type'] == 'number'
-        assert properties['decimal2']['multipleOf'] == .0001
+        assert properties['decimal2'] == {'type': 'string', 'format': 'decimal'}
 
         assert properties['email']['type'] == 'string'
         assert properties['email']['format'] == 'email'