More liberal flask number converters for float and int in paths (#1306)

* Use more liberal flask converters for float and int

These don't try to enforce a "single representation" of paths but instead try to convert the numbers that callers pass in.

Addresses #1040 and #1041

* Use f-strings instead of string concat or %-formats

* Complying with style rules added long after this PR was made

connexion/apps/flask_app.py

@@ -27,6 +27,8 @@ class FlaskApp(AbstractApp):
     def create_app(self):
         app = flask.Flask(self.import_name, **self.server_args)
         app.json_encoder = FlaskJSONEncoder
+        app.url_map.converters['float'] = NumberConverter
+        app.url_map.converters['int'] = IntegerConverter
         return app
 
     def get_root_path(self):
@@ -142,3 +144,19 @@ class FlaskJSONEncoder(json.JSONEncoder):
             return float(o)
 
         return json.JSONEncoder.default(self, o)
+
+
+class NumberConverter(werkzeug.routing.BaseConverter):
+    """ Flask converter for OpenAPI number type """
+    regex = r"[+-]?[0-9]*(\.[0-9]*)?"
+
+    def to_python(self, value):
+        return float(value)
+
+
+class IntegerConverter(werkzeug.routing.BaseConverter):
+    """ Flask converter for OpenAPI integer type """
+    regex = r"[+-]?[0-9]+"
+
+    def to_python(self, value):
+        return int(value)

tests/api/test_parameters.py

@@ -1,6 +1,8 @@
 import json
 from io import BytesIO
 
+import pytest
+
 
 def test_parameter_validation(simple_app):
     app_client = simple_app.app.test_client()
@@ -124,22 +126,57 @@ def test_strict_formdata_param(strict_app):
     assert resp.status_code == 200
 
 
-def test_path_parameter_someint(simple_app):
+@pytest.mark.parametrize('arg, result', [
+    # The cases accepted by the Flask/Werkzeug converter
+    ['123', 'int 123'],
+    ['0', 'int 0'],
+    ['0000', 'int 0'],
+    # Additional cases that we want to support
+    ['+123', 'int 123'],
+    ['+0', 'int 0'],
+    ['-0', 'int 0'],
+    ['-123', 'int -123'],
+])
+def test_path_parameter_someint(simple_app, arg, result):
+    assert isinstance(arg, str)  # sanity check
     app_client = simple_app.app.test_client()
-    resp = app_client.get('/v1.0/test-int-path/123')  # type: flask.Response
+    resp = app_client.get(f'/v1.0/test-int-path/{arg}')  # type: flask.Response
-    assert resp.data.decode('utf-8', 'replace') == '"int"\n'
+    assert resp.data.decode('utf-8', 'replace') == f'"{result}"\n'
 
+
+def test_path_parameter_someint__bad(simple_app):
     # non-integer values will not match Flask route
+    app_client = simple_app.app.test_client()
     resp = app_client.get('/v1.0/test-int-path/foo')  # type: flask.Response
     assert resp.status_code == 404
 
 
-def test_path_parameter_somefloat(simple_app):
+@pytest.mark.parametrize('arg, result', [
+    # The cases accepted by the Flask/Werkzeug converter
+    ['123.45', 'float 123.45'],
+    ['123.0', 'float 123'],
+    ['0.999999999999999999', 'float 1'],
+    # Additional cases that we want to support
+    ['+123.45', 'float 123.45'],
+    ['-123.45', 'float -123.45'],
+    ['123.', 'float 123'],
+    ['.45', 'float 0.45'],
+    ['123', 'float 123'],
+    ['0', 'float 0'],
+    ['0000', 'float 0'],
+    ['-0.000000001', 'float -1e-09'],
+    ['100000000000', 'float 1e+11'],
+])
+def test_path_parameter_somefloat(simple_app, arg, result):
+    assert isinstance(arg, str)  # sanity check
     app_client = simple_app.app.test_client()
-    resp = app_client.get('/v1.0/test-float-path/123.45')  # type: flask.Response
+    resp = app_client.get(f'/v1.0/test-float-path/{arg}')  # type: flask.Response
-    assert resp.data.decode('utf-8' , 'replace') == '"float"\n'
+    assert resp.data.decode('utf-8', 'replace') == f'"{result}"\n'
 
+
+def test_path_parameter_somefloat__bad(simple_app):
     # non-float values will not match Flask route
+    app_client = simple_app.app.test_client()
     resp = app_client.get('/v1.0/test-float-path/123,45')  # type: flask.Response
     assert resp.status_code == 404
 

tests/fakeapi/hello/__init__.py

@@ -266,11 +266,11 @@ def test_schema_int(test_int):
 
 
 def test_get_someint(someint):
-    return type(someint).__name__
+    return f'{type(someint).__name__} {someint:g}'
 
 
 def test_get_somefloat(somefloat):
-    return type(somefloat).__name__
+    return f'{type(somefloat).__name__} {somefloat:g}'
 
 
 def test_default_param(name):