Synchronous and Asynchronous Requests
To begin, Robyn taught Batman about its ability to handle both synchronous and asynchronous requests. Batman was excited to learn about these features and started implementing them in the application.
For a simple synchronous request, Batman wrote:
Request
from robyn import Robyn
app = Robyn(__file__)
@app.get("/")
def h(request):
return "Hello, world"
app.start(port=8080, host="0.0.0.0") # host is optional, defaults to 127.0.0.1
For an asynchronous request, Batman used:
Request
@app.get("/")
async def h(request):
return "Hello, world"
Running the Application
Batman was curious about how to run the application. Robyn explained that he could run the application through a simple command python3 app.py
A robyn application exposes certain commands to the user. These commands can be used to run the application, or to generate a new project.
Request
usage: app.py [-h] [--processes PROCESSES] [--workers WORKERS] [--log-level LOG_LEVEL] [--create] [--docs] [--open-browser] [--version]
Robyn, a fast async web framework with a rust runtime.
options:
-h, --help show this help message and exit
--processes PROCESSES
Choose the number of processes. [Default: 1]
--workers WORKERS Choose the number of workers. [Default: 1]
--dev Development mode. It restarts the server based on file changes.
--log-level LOG_LEVEL
Set the log level name
--create Create a new project template.
--docs Open the Robyn documentation.
--open-browser Open the browser on successful start.
--version Show the Robyn version.
--compile-rust-path COMPILE_RUST_PATH
Compile rust files in the given path.
--create-rust-file CREATE_RUST_FILE
Create a rust file with the given name.
--disable-openapi Disable the OpenAPI documentation.
--fast Fast mode. It sets the optimal values for processes, workers and log level. However, you can override them.
Or the application can be run using Robyn's CLI, i.e. using python -m robyn app.py
Request
usage: python -m robyn app.py [-h] [--processes PROCESSES] [--workers WORKERS] [--dev] [--log-level LOG_LEVEL] [--create] [--docs] [--open-browser] [--version]
Robyn, a fast async web framework with a rust runtime.
options:
-h, --help show this help message and exit
--processes PROCESSES
Choose the number of processes. [Default: 1]
--workers WORKERS Choose the number of workers. [Default: 1]
--dev Development mode. It restarts the server based on file changes.
--log-level LOG_LEVEL
Set the log level name
--create Create a new project template.
--docs Open the Robyn documentation.
--open-browser Open the browser on successful start.
--version Show the Robyn version.
--compile-rust-path COMPILE_RUST_PATH
Compile rust files in the given path.
--create-rust-file CREATE_RUST_FILE
Create a rust file with the given name.
--disable-openapi Disable the OpenAPI documentation.
--fast Fast mode. It sets the optimal values for processes, workers and log level. However, you can override them.
Handling Different HTTP Requests
Robyn then taught Batman how to handle various HTTP requests like GET, POST, PUT, PATCH, and DELETE. With Robyn's guidance, Batman could create endpoints for each request type, making the application versatile and efficient.
For example, Batman learned to create a POST request like this:
Request
@app.post("/")
async def h(request):
return "Hello World"
Returning JSON Responses
Batman was curios about the ability to return JSON responses from the application. Robyn showed him how to do this using the jsonify function.
Batman could now return JSON responses from his application, making it easier to parse the data on the frontend.
Request
from robyn import jsonify
@app.post("/jsonify")
async def json(request):
return {"hello": "world"}
Accessing Path Parameters and Query Parameters
Batman was curious about how to access path parameters and query parameters from incoming requests. This allowed Batman to create dynamic routes and gather specific information from the request.
Robyn also showed Batman how to access path parameters and query parameters from incoming requests.
For instance, Batman could create a route with a path parameter and access it like this:
Request
from robyn import jsonify
@app.post("/jsonify/:id")
async def json(request, path_params):
print(request.path_params["id"])
print(path_params["id"])
assert request.path_params["id"] == path_params["id"]
return {"hello": "world"}
And for accessing query parameters, Batman could use the following code snippet:
Request
@app.get("/query")
async def query_get(request, query_params):
query_data = query_params.to_dict()
assert query_data == request.query_params.to_dict()
return jsonify(query_data)
Any request param can be used in the handler function either using type annotations or using the reserved names.
Do note that the type annotations will take precedence over the reserved names.
Robyn showed Batman example syntaxes of accessing the request params:
Request
from robyn.robyn import QueryParams, Headers
from robyn.types import PathParams, RequestMethod, RequestBody, RequestURL
@app.get("/untyped/query_params")
def untyped_basic(query_params):
return query_params.to_dict()
@app.get("/typed/query_params")
def typed_basic(query_data: QueryParams):
return query_data.to_dict()
@app.get("/untyped/path_params/:id")
def untyped_path_params(query_params: PathParams):
return query_params # contains the path params since the type annotations takes precedence over the reserved names
@app.post("/typed_untyped/combined")
def typed_untyped_combined(
query_params,
method_data: RequestMethod,
body_data: RequestBody,
url: RequestURL,
headers_item: Headers,
):
return {
"body": body_data,
"query_params": query_params.to_dict(),
"method": method_data,
"url": url.path,
"headers": headers_item.get("server"),
}
Type Aliases: Request, QueryParams, Headers, PathParams, RequestBody, RequestMethod, RequestURL, FormData, RequestFiles, RequestIP, RequestIdentity
Reserved Names: r, req, request, query_params, headers, path_params, body, method, url, ip_addr, identity, form_data, files
As Batman continued to develop his web application with Robyn, he explored more features and implemented them using code samples.
Customizing Response Formats and Headers
After understanding the dynamic nature of Robyn, Batman, now wanted the ability to customize response formats and headers. Robyn showed him how to do this using dictionaries and Robyn's Response object.
Using Dictionaries
Batman learned to customize response formats by returning dictionaries or using Robyn's Response object. He could also set status codes and headers for each response. For example, Batman created a response with a dictionary like this:
Request
@app.post("/dictionary")
async def dictionary(request):
return {
"status_code": 200,
"description": "This is a regular response",
"type": "text",
"headers": {"Header": "header_value"},
}
Using the Response object
To use the Response object, he wrote:
Request
from robyn.robyn import Response
@app.get("/response")
async def response(request):
return Response(status_code=200, headers=Headers({}), description="OK")
Returning a Binary Output
Batman then wanted to return a binary output from his application. He could do this by setting the type of the response to "binary" and returning a bytes object. For example, he wrote:
Request
@app.get("/binary_output_response_sync")
def binary_output_response_sync(request):
return Response(
status_code=200,
headers={"Content-Type": "application/octet-stream"},
description="OK",
)
@app.get("/binary_output_async")
async def binary_output_async(request):
return b"OK"
@app.get("/binary_output_response_async")
async def binary_output_response_async(request):
return Response(
status_code=200,
headers={"Content-Type": "application/octet-stream"},
description="OK",
)
Response Headers
Batman, being the world's greatest detective, spotted the headers field in the Response object. He, naturally wanted to know more about it. Robyn explained that he could use the headers field to set response headers. For example, he could set the Content-Type header to application/json by writing:
Local Response Headers
Either, by using the headers field in the Response object:
Request
@app.get("/")
def binary_output_response_sync(request):
return Response(
status_code=200,
headers={"Content-Type": "application/octet-stream"},
description="OK",
)
Global Response Headers
Request
app.add_response_header("content-type", "application/json")
add_response_header appends the header to the list of headers, while set_response_header replaces the header if it exists.
Request
app.set_response_header("content-type", "application/json")
To prevent the headers from getting applied to certain endpoints, you can use the exclude_response_headers_for function.
Request
app.exclude_response_headers_for(["/login", "/signup"])
Cookies
Set cookies using the set_cookies function.
Request
@app.get("/")
def binary_output_response_sync(request):
response = Response(200, {'type': 'int'}, "desc")
response.set_cookie(key="fakesession", value="fake-cookie-session-value")
return response
Request Headers
Batman, now wanted to know how to read request headers. Robyn explained that he could use the request.headers field to read request headers. For example, he could read the Content-Type header by writing:
Local Request Headers
Either, by using the headers field in the Request object:
Request
@app.get("/")
def binary_output_response_sync(request):
headers = request.headers
print("These are the request headers: ", headers)
existing_header = headers.get("exisiting_header")
existing_header = headers.get("exisiting_header", "default_value")
exisiting_header = headers["exisiting_header"] # This syntax is also valid
headers.set("modified", "modified_value")
headers["new_header"] = "new_value" # This syntax is also valid
print("These are the modified request headers: ", headers)
return ""
Or by using the global Request Headers:
Request
app.add_request_header("server", "robyn")
add_request_header appends the header to the list of headers, while set_request_header replaces the header if it exists.
Request
app.set_request_header("server", "robyn")
Status Codes
After learning about response formats and headers, Batman learned to set status codes for his responses.
Request
from robyn import status_codes
@app.get("/response")
async def response(request):
return Response(status_code=status_codes.HTTP_200_OK, headers=Headers({}), description="OK")
What's next?
Great, now Robyn, what is the Request Object that you keep talking about?, Batman said. "Next section", said Robyn.
Batman was also interested to know about the architecture of Robyn. "Next section", said Robyn.