diff --git a/template/api.mustache b/template/api.mustache
index e3372c7f..50710e06 100644
--- a/template/api.mustache
+++ b/template/api.mustache
@@ -8,6 +8,19 @@ from typing_extensions import Annotated
 {{#imports}}
 {{import}}
 {{/imports}}
+{{#operations.operation}}
+{{! Workaround for missing imports for parameters that use oneOf }}
+{{#allParams}}
+{{^hasDiscriminatorWithNonEmptyMapping}}
+{{#composedSchemas.oneOf}}
+{{#-first}}
+from {{packageName}}.models.{{#lambda.snakecase}}{{schema.complexType}}{{/lambda.snakecase}} import {{schema.complexType}}
+from datetime import datetime, date, timezone
+{{/-first}}
+{{/composedSchemas.oneOf}}
+{{/hasDiscriminatorWithNonEmptyMapping}}
+{{/allParams}}
+{{/operations.operation}}
 from {{packageName}}.api_client import ApiClient, RequestSerialized
 from {{packageName}}.api_response import ApiResponse
 from {{packageName}}.configuration import Configuration
@@ -117,6 +130,7 @@ class {{classname}}:
 {{#queryParams}}
         # process the query parameters
         if {{paramName}} is not None:
+            {{^schema.composedSchemas.oneOf}}
             {{#isDateTime}}
             if isinstance({{paramName}}, datetime):
                 _query_params.append(
@@ -146,6 +160,27 @@ class {{classname}}:
             {{^isDateTime}}{{^isDate}}
             _query_params.append(('{{baseName}}', {{paramName}}{{#isEnumRef}}.value{{/isEnumRef}}))
             {{/isDate}}{{/isDateTime}}
+            {{/schema.composedSchemas.oneOf}}
+            {{#schema.composedSchemas.oneOf}}
+            {{#-first}}
+            if isinstance({{paramName}}, datetime):
+                _query_params.append(
+                    (
+                        '{{schema.baseName}}',
+                        {{paramName}}.isoformat(timespec='microseconds')
+                    )
+                )
+            elif isinstance({{paramName}}, date):
+                _query_params.append(
+                    (
+                        '{{schema.baseName}}',
+                        {{paramName}}.isoformat()
+                    )
+                )
+            else:
+                _query_params.append(('{{schema.baseName}}', {{paramName}}))
+            {{/-first}}
+            {{/schema.composedSchemas.oneOf}}
 {{/queryParams}}
 
 {{#headerParams}}
diff --git a/template/model_doc.mustache b/template/model_doc.mustache
index 9bc9dd8b..054ad333 100644
--- a/template/model_doc.mustache
+++ b/template/model_doc.mustache
@@ -11,6 +11,17 @@ Name | Type | Description | Notes
 {{#vars}}**{{name}}** | {{#isPrimitiveType}}**{{dataType}}**{{/isPrimitiveType}}{{^isPrimitiveType}}[**{{dataType}}**]({{complexType}}.md){{/isPrimitiveType}} | {{{description}}} | {{^required}}[optional] {{/required}}{{#isReadOnly}}[readonly] {{/isReadOnly}}{{#defaultValue}}[default to {{{.}}}]{{/defaultValue}}
 {{/vars}}
 {{/emptyVars}}
+{{#emptyVars}}
+{{^model.discriminator}}
+{{#composedSchemas.oneOf}}
+{{#-first}}
+## Type alias
+
+`Union[{{#oneOf}}{{^-last}}{{.}},{{/-last}}{{#-last}}{{.}}{{/-last}}{{/oneOf}}]`
+{{/-first}}
+{{/composedSchemas.oneOf}}
+{{/model.discriminator}}
+{{/emptyVars}}
 {{/isEnum}}
 {{#isEnum}}
 ## Enum
diff --git a/template/model_oneof.mustache b/template/model_oneof.mustache
index 958812d7..e04708a0 100644
--- a/template/model_oneof.mustache
+++ b/template/model_oneof.mustache
@@ -1,3 +1,4 @@
+{{#hasDiscriminatorWithNonEmptyMapping}}
 from __future__ import annotations
 import json
 import pprint
@@ -206,3 +207,13 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
 # TODO: Rewrite to not use raise_errors
 {{classname}}.model_rebuild(raise_errors=False)
 {{/vendorExtensions.x-py-postponed-model-imports.size}}
+{{/hasDiscriminatorWithNonEmptyMapping}}
+{{^hasDiscriminatorWithNonEmptyMapping}}
+from typing import Union
+{{#composedSchemas.oneOf}}
+{{#isDateTime}}
+from pydantic import AwareDatetime
+{{/isDateTime}}
+{{/composedSchemas.oneOf}}
+{{classname}} = Union[{{#composedSchemas.oneOf}}{{#isDateTime}}AwareDatetime{{/isDateTime}}{{^isDateTime}}{{dataType}}{{/isDateTime}}{{^-last}},{{/-last}}{{/composedSchemas.oneOf}}]
+{{/hasDiscriminatorWithNonEmptyMapping}}
\ No newline at end of file
diff --git a/template/partial_api_args.mustache b/template/partial_api_args.mustache
index 21eea6ed..3d145a39 100644
--- a/template/partial_api_args.mustache
+++ b/template/partial_api_args.mustache
@@ -1,7 +1,7 @@
 (
         self,
         {{#allParams}}
-        {{paramName}}: {{{vendorExtensions.x-py-typing}}}{{^required}} = None{{/required}},
+        {{paramName}}: {{^schema.composedSchemas}}{{{vendorExtensions.x-py-typing}}}{{/schema.composedSchemas}}{{#schema.composedSchemas}}Annotated[{{^required}}Optional[{{/required}}{{schema.complexType}}{{^required}}]{{/required}},Field(description="{{{description}}}",)]{{/schema.composedSchemas}}{{^required}} = None{{/required}},
         {{/allParams}}
         _request_timeout: Union[
             None,