diff --git a/poetry.lock b/poetry.lock
index fe390e8..58e0745 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -367,6 +367,17 @@ docs = ["furo", "jaraco.packaging (>=9)", "jaraco.tidelift (>=1.4)", "rst.linker
 perf = ["ipython"]
 testing = ["flufl.flake8", "importlib-resources (>=1.3)", "packaging", "pyfakefs", "pytest (>=6)", "pytest-black (>=0.3.7)", "pytest-checkdocs (>=2.4)", "pytest-cov", "pytest-enabler (>=1.3)", "pytest-mypy (>=0.9.1)", "pytest-perf (>=0.9.2)", "pytest-ruff"]
 
+[[package]]
+name = "inflection"
+version = "0.5.1"
+description = "A port of Ruby on Rails inflector to Python"
+optional = false
+python-versions = ">=3.5"
+files = [
+    {file = "inflection-0.5.1-py2.py3-none-any.whl", hash = "sha256:f38b2b640938a4f35ade69ac3d053042959b62a0f1076a5bbaa1b9526605a8a2"},
+    {file = "inflection-0.5.1.tar.gz", hash = "sha256:1a29730d366e996aaacffb2f1f1cb9593dc38e2ddd30c91250c6dde09ea9b417"},
+]
+
 [[package]]
 name = "iniconfig"
 version = "2.0.0"
@@ -1505,4 +1516,4 @@ testing = ["big-O", "flake8 (<5)", "jaraco.functools", "jaraco.itertools", "more
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.7"
-content-hash = "bc16e9c8d9b067e6cee6870a30473e74a8c641305f5da551b9157f96c1546bee"
+content-hash = "e29038a3548768e3be7cc1bce96c0170325667dff52ebf2126f63536fbd82e0f"
diff --git a/pyproject.toml b/pyproject.toml
index 3ab7e97..909700d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,6 +20,7 @@ classifiers = [
 python = "^3.7"
 requests = "^2.28.1"
 portalocker = "^2.7.0"
+inflection = "^0.5.1"
 
 [tool.poetry.group.dev]
 optional = true
diff --git a/test/test_util.py b/test/test_util.py
index 021194c..4f58f19 100644
--- a/test/test_util.py
+++ b/test/test_util.py
@@ -10,6 +10,7 @@
     clean_request_params,
     clean_request_payload,
     find_model_id,
+    to_camel_case,
     to_snake_case,
 )
 
@@ -129,7 +130,8 @@ def test_clean_datetime(dt, expected, request):
         "FOOBar",
     ],
 )
-def test_to_snake_case(input):
+def test_case_converters(input):
+    assert to_camel_case(input) == "fooBar"
     assert to_snake_case(input) == "foo_bar"
 
 
diff --git a/welkin/util.py b/welkin/util.py
index 4424dd8..c92cdc5 100644
--- a/welkin/util.py
+++ b/welkin/util.py
@@ -1,10 +1,12 @@
-import functools
-import re
 from datetime import date, datetime, timezone
+from functools import cache, wraps
+from types import FunctionType
 from typing import Any
 from uuid import UUID
 
-from welkin.models.base import SchemaBase
+import inflection
+
+from welkin.models.base import Collection, Resource, SchemaBase
 
 # NOTE: `clean_request_payload` and `clean_request_params` are intentionally DRY
 # violations. The code may be the same, but they represent different knowledge.
@@ -111,21 +113,46 @@ def clean_datetime(dt: datetime) -> str:
     )
 
 
-def find_model_id(obj, model: str):
-    if obj.__class__.__name__ == model:
-        return obj.id
-    elif hasattr(obj, f"{to_snake_case(model)}Id"):
-        return obj.patientId
-    elif obj._parent:
-        return find_model_id(obj._parent, model)
+def find_model_id(instance: Collection | Resource, model_name: str) -> str:
+    """Recursively traverse the `_parent` chain searching for a model id.
 
-    raise AttributeError(f"Cannot find {model} id. Model._parent chain ends in {obj}")
+    Args:
+        instance (Collection | Resource): The instanceect instance to inspect.
+        model_name (str): The class name of the model to find.
 
+    Raises:
+        AttributeError: If recursion ends without finding the model id.
 
-def model_id(*models):
-    def decorator(f):
-        @functools.wraps(f)
-        def wrapper(self, *args, **kwargs):
+    Returns:
+        str: The model id.
+    """
+    body_id_key = f"{to_camel_case(model_name)}Id"
+
+    if instance.__class__.__name__ == model_name:
+        return instance.id
+    elif hasattr(instance, body_id_key):
+        return getattr(instance, body_id_key)
+    elif instance._parent:
+        return find_model_id(instance._parent, model_name)
+
+    raise AttributeError(
+        f"Cannot find {model_name} id. Model._parent chain ends in {instance}"
+    )
+
+
+def model_id(*models: tuple[str]) -> FunctionType:
+    """Insert values for `model_id` arguments if not provided.
+
+    Args:
+        *models (tuple[str]): The model names to search for.
+
+    Raises:
+        TypeError: If no ID is found and no arguments are provided.
+    """
+
+    def decorator(f: FunctionType):
+        @wraps(f)
+        def wrapper(self, *args, **kwargs) -> FunctionType:
             outer_exc = None
             for model in models:
                 key = f"{to_snake_case(model)}_id"
@@ -139,6 +166,7 @@ def wrapper(self, *args, **kwargs):
             try:
                 return f(self, *args, **kwargs)
             except TypeError as exc:
+                # Raise from the outer `AttributeError` so we don't lose context.
                 raise exc from outer_exc
 
         return wrapper
@@ -146,9 +174,27 @@ def wrapper(self, *args, **kwargs):
     return decorator
 
 
-def to_snake_case(s):
-    first = re.compile(r"(.)([A-Z][a-z]+)")
-    second = re.compile(r"([a-z0-9])([A-Z])")
-    repl = r"\1_\2"
+@cache
+def to_camel_case(s: str) -> str:
+    """Convert a string to camelCase.
+
+    Args:
+        s (str): The string to convert.
+
+    Returns:
+        str: The converted camelCase string.
+    """
+    return inflection.camelize(to_snake_case(s), uppercase_first_letter=False)
+
+
+@cache
+def to_snake_case(s: str) -> str:
+    """Convert a string to snake_case.
+
+    Args:
+        s (str): The string to convert.
 
-    return second.sub(repl, first.sub(repl, s)).lower()
+    Returns:
+        str: The converted snake_case string.
+    """
+    return inflection.underscore(s)