new to_lower_camel() function (#3473)

* Create utils.py

I needed non pascal case camel case support

* write tests for new `to_lower_camel()` function

* Create 3463-schlerp.md

* added mention to to_lower_camel()

* changed quotes to single tick

* adding second blank line at end of file.

* again, adding second blank line...

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

changes/3463-schlerp.md

@@ -0,0 +1 @@
+created new function `to_lower_camel()` for "non pascal case" camel case.

docs/usage/model_config.md

@@ -143,7 +143,7 @@ _(This script is complete, it should run "as is")_
 
 Here camel case refers to ["upper camel case"](https://en.wikipedia.org/wiki/Camel_case) aka pascal case
 e.g. `CamelCase`. If you'd like instead to use lower camel case e.g. `camelCase`,
-it should be trivial to modify the `to_camel` function above.
+instead use the `to_lower_camel` function.
 
 ## Alias Precedence
 

pydantic/utils.py

@@ -303,6 +303,13 @@ def to_camel(string: str) -> str:
     return ''.join(word.capitalize() for word in string.split('_'))
 
 
+def to_lower_camel(string: str) -> str:
+    if len(string) >= 1:
+        pascal_string = to_camel(string)
+        return pascal_string[0].lower() + pascal_string[1:]
+    return string.lower()
+
+
 T = TypeVar('T')
 
 

tests/test_utils.py

@@ -37,6 +37,7 @@ from pydantic.utils import (
     lenient_issubclass,
     path_type,
     smart_deepcopy,
+    to_lower_camel,
     truncate,
     unique_list,
 )
@@ -528,6 +529,18 @@ def test_undefined_pickle():
     assert undefined2 is Undefined
 
 
+def test_on_lower_camel_zero_length():
+    assert to_lower_camel('') == ''
+
+
+def test_on_lower_camel_one_length():
+    assert to_lower_camel('a') == 'a'
+
+
+def test_on_lower_camel_many_length():
+    assert to_lower_camel('i_like_turtles') == 'iLikeTurtles'
+
+
 def test_limited_dict():
     d = LimitedDict(10)
     d[1] = '1'