Allow setting trim_whitespace globally through API settings

docs/api-guide/fields.md

@@ -158,12 +158,12 @@ A text representation. Optionally validates the text to be shorter than `max_len
 
 Corresponds to `django.db.models.fields.CharField` or `django.db.models.fields.TextField`.
 
-**Signature:** `CharField(max_length=None, min_length=None, allow_blank=False, trim_whitespace=True)`
+**Signature:** `CharField(max_length=None, min_length=None, allow_blank=False, trim_whitespace=api_settings.TRIM_WHITESPACE)`
 
 - `max_length` - Validates that the input contains no more than this number of characters.
 - `min_length` - Validates that the input contains no fewer than this number of characters.
 - `allow_blank` - If set to `True` then the empty string should be considered a valid value. If set to `False` then the empty string is considered invalid and will raise a validation error. Defaults to `False`.
-- `trim_whitespace` - If set to `True` then leading and trailing whitespace is trimmed. Defaults to `True`.
+- `trim_whitespace` - If set to `True` then leading and trailing whitespace is trimmed. Defaults to the `TRIM_WHITESPACE` settings key which is `True` by default.
 
 The `allow_null` option is also available for string fields, although its usage is discouraged in favor of `allow_blank`. It is valid to set both `allow_blank=True` and `allow_null=True`, but doing so means that there will be two differing types of empty value permissible for string representations, which can lead to data inconsistencies and subtle application bugs.
 

rest_framework/fields.py

@@ -768,7 +768,7 @@ class CharField(Field):
 
     def __init__(self, **kwargs):
         self.allow_blank = kwargs.pop('allow_blank', False)
-        self.trim_whitespace = kwargs.pop('trim_whitespace', True)
+        self.trim_whitespace = kwargs.pop('trim_whitespace', api_settings.TRIM_WHITESPACE)
         self.max_length = kwargs.pop('max_length', None)
         self.min_length = kwargs.pop('min_length', None)
         super().__init__(**kwargs)

rest_framework/settings.py

@@ -113,6 +113,7 @@ DEFAULTS = {
     'STRICT_JSON': True,
     'COERCE_DECIMAL_TO_STRING': True,
     'UPLOADED_FILES_USE_URL': True,
+    'TRIM_WHITESPACE': True,
 
     # Browseable API
     'HTML_SELECT_CUTOFF': 1000,