🐛 Fix path and query parameters receiving dict as valid (#287)

* 🐛 Fix path and query parameters accepting dict

* ✅ Add several tests to ensure invalid types are not accepted

* 📝 Document (to include tested source) using query params with list

* 🐛 Fix OpenAPI schema in query with list tutorial

tests/test_tutorial/test_query_params_str_validations/test_tutorial011.py

@@ -86,3 +86,10 @@ def test_multi_query_values():
     response = client.get(url)
     assert response.status_code == 200
     assert response.json() == {"q": ["foo", "bar"]}
+
+
+def test_query_no_values():
+    url = "/items/"
+    response = client.get(url)
+    assert response.status_code == 200
+    assert response.json() == {"q": None}

tests/test_tutorial/test_query_params_str_validations/test_tutorial013.py

@@ -0,0 +1,91 @@
+from starlette.testclient import TestClient
+
+from query_params_str_validations.tutorial013 import app
+
+client = TestClient(app)
+
+openapi_schema = {
+    "openapi": "3.0.2",
+    "info": {"title": "Fast API", "version": "0.1.0"},
+    "paths": {
+        "/items/": {
+            "get": {
+                "responses": {
+                    "200": {
+                        "description": "Successful Response",
+                        "content": {"application/json": {"schema": {}}},
+                    },
+                    "422": {
+                        "description": "Validation Error",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "$ref": "#/components/schemas/HTTPValidationError"
+                                }
+                            }
+                        },
+                    },
+                },
+                "summary": "Read Items",
+                "operationId": "read_items_items__get",
+                "parameters": [
+                    {
+                        "required": False,
+                        "schema": {"title": "Q", "type": "array"},
+                        "name": "q",
+                        "in": "query",
+                    }
+                ],
+            }
+        }
+    },
+    "components": {
+        "schemas": {
+            "ValidationError": {
+                "title": "ValidationError",
+                "required": ["loc", "msg", "type"],
+                "type": "object",
+                "properties": {
+                    "loc": {
+                        "title": "Location",
+                        "type": "array",
+                        "items": {"type": "string"},
+                    },
+                    "msg": {"title": "Message", "type": "string"},
+                    "type": {"title": "Error Type", "type": "string"},
+                },
+            },
+            "HTTPValidationError": {
+                "title": "HTTPValidationError",
+                "type": "object",
+                "properties": {
+                    "detail": {
+                        "title": "Detail",
+                        "type": "array",
+                        "items": {"$ref": "#/components/schemas/ValidationError"},
+                    }
+                },
+            },
+        }
+    },
+}
+
+
+def test_openapi_schema():
+    response = client.get("/openapi.json")
+    assert response.status_code == 200
+    assert response.json() == openapi_schema
+
+
+def test_multi_query_values():
+    url = "/items/?q=foo&q=bar"
+    response = client.get(url)
+    assert response.status_code == 200
+    assert response.json() == {"q": ["foo", "bar"]}
+
+
+def test_query_no_values():
+    url = "/items/"
+    response = client.get(url)
+    assert response.status_code == 200
+    assert response.json() == {"q": None}