feat: add python flask petstore example [skip ci]

.gitignore

@@ -1,3 +1,7 @@
+# Haskell
 dist-newstyle/
 cabal.project.local*
 dist
+
+# Python
+__pycache__/

example/petstore-python-flask/Makefile

@@ -0,0 +1,2 @@
+all:
+	 flask --app petstore run

example/petstore-python-flask/petstore-with-jwt.py

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+from flask import Flask
+from flask import jsonify
+from flask import request
+
+from flask_jwt_extended import create_access_token
+from flask_jwt_extended import get_jwt_identity
+from flask_jwt_extended import jwt_required
+from flask_jwt_extended import JWTManager
+
+app = Flask(__name__)
+
+# Setup the Flask-JWT-Extended extension
+app.config["JWT_SECRET_KEY"] = "super-secret"  # Change this!
+jwt = JWTManager(app)
+
+
+# Create a route to authenticate your users and return JWTs. The
+# create_access_token() function is used to actually generate the JWT.
+@app.route("/login", methods=["POST"])
+def login():
+    username = request.json.get("username", None)
+    password = request.json.get("password", None)
+    if username != "test" or password != "test":
+        return jsonify({"msg": "Bad username or password"}), 401
+
+    access_token = create_access_token(identity=username)
+    return jsonify(access_token=access_token)
+
+
+# Protect a route with jwt_required, which will kick out requests
+# without a valid JWT present.
+@app.route("/protected", methods=["GET"])
+@jwt_required()
+def protected():
+    # Access the identity of the current user with get_jwt_identity
+    current_user = get_jwt_identity()
+    return jsonify(logged_in_as=current_user), 200
+
+
+if __name__ == "__main__":
+    app.run()

example/petstore-python-flask/petstore.py

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+from flask import Flask
+from flask import jsonify
+from flask import request
+
+app = Flask(__name__)
+
+# NOTE: Not thread-safe and won't work if clients connect concurrently.
+petstore = {}
+
+@app.route("/pet/<pet_id>", methods=["GET"])
+def get_pet(pet_id):
+    if pet_id in petstore:
+        pet_name = petstore[pet_id]
+        return jsonify(petId=pet_id, petName=pet_name)
+    else:
+        return "Pet not found", 404
+
+@app.route("/pet", methods=["POST"])
+def add_pet():
+    pet_id = request.json.get("petId", None)
+    pet_name = request.json.get("petName", None)
+    if pet_id in petstore:
+        return jsonify(error="Pet already exists"), 409
+    petstore[pet_id] = pet_name
+    return "[]", 201
+
+@app.route("/health", methods=["GET"])
+def health():
+    return "[]", 200
+
+@app.route("/_reset", methods=["DELETE"])
+def _reset():
+    petstore.clear()
+    return "[]", 200
+
+if __name__ == "__main__":
+    app.run()

example/petstore-python-flask/shell.nix

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+let
+  nixpkgs = fetchTarball "https://github.com/NixOS/nixpkgs/archive/refs/tags/24.05.tar.gz";
+  pkgs = import nixpkgs { config = {}; overlays = []; };
+in
+
+pkgs.mkShell {
+  packages = with pkgs; [
+    (pkgs.python3.withPackages (python-pkgs: with python-pkgs; [
+      flask
+      flask-jwt-extended
+    ]))
+  ];
+}