As we saw in the Request chapter, Emmett provides several tools for handling requests from clients.
However, since your application has to produce responses to these requests, Emmett also supplies some tools for that.
As for the request object, Emmett stores some data in the response object,
data which will be used when the request has been processed and the output
is pushed back to the client.
Accessing the response object is as simple as accessing a request:
from emmett import response
and this is the list of attributes you can deal with:
| attribute | description |
|---|---|
| status | HTTP status for the response, set on 200 unless an exception/redirect/abort occurs |
| cookies | contains the cookies that will be pushed to the client |
| headers | HTTP headers for the response |
| meta | meta tags for the response |
| meta_prop | meta properties tags for the response |
If you need to set a cookie you can just write:
response.cookies['yourcookiename'] = 'yourdata'
response.cookies['yourcookiename']['path'] = '/'
or to set a header:
response.headers['Cache-Control'] = 'private'
HTML has 2 kind of meta tags:
<meta property="og:title" content="Walter Bishop's place" />
<meta name="description" content="A pocket universe" />
they can be very helpful for improving your application's SEO.
Instead of manually writing them in your templates, you can add these tags to your response in an easier way. Lets say, for example, that we have a blog and we want to automatically add our meta tags on a single post:
@app.route("/p/<int:post_id>")
async def single(post_id):
post = somedb.findmypost(post_id)
response.meta.title = "MyBlog - "+post.title
response.meta.keywords = ",".join(key for key in post.keywords)
response.meta_prop["og:title"] = response.meta.title
Then, in your template, you can just write:
<html>
<head>
<title>{{ =current.response.meta.title }}</title>
{{ include_meta }}
</head>
and you will have all the meta tags included in your HTML.
New in version 2.6
Emmett Response object also provides some wrapping methods in order to respond with files or streams of data, specifically:
wrap_iterwrap_aiterwrap_filewrap_ioThese methods can be used to produce responses from iterators and files.
The wrap_iter and wrap_aiter methods are very similar, both accepts iterables: you can use the latter for asynchronous iterators:
def iterator():
for _ in range(3):
yield b"hello"
async def aiterator():
for _ in range(3):
yield b"hello"
@app.route()
async def response_iter():
return response.wrap_iter(iterator())
@app.route()
async def response_aiter():
return response.wrap_aiter(aiterator())
You can produce responses from file using two different methods in Emmett:
wrap_file when you want to create a response from a pathwrap_io when you want to create a response from a file-like object@app.route("/file/<name:str>")
async def file(name):
return response.wrap_file(f"assets/{name}")
@app.route("/io/<name:str>")
async def io(name):
with open(f"assets/{name}", "r") as f:
return response.wrap_io(f)
When you need to store a message at the end of one request, and access it
during the next one, Emmett's response.alerts() become quite handy.
For example, you may want to send a success alert to the user. Let's say you have function which exposes a form, you can use message flashing to alert the user the form was accepted:
from emmett.helpers import flash
@app.route("/someurl")
async def myform():
form = await Form()
if form.accepted:
flash("We stored your question!")
return dict(form=form)
then, in your template, you can access the flashed messages using response:
<div class="container">
{{ for flash in current.response.alerts(): }}
<div class="myflashstyle">{{ =flash }}</div>
{{ pass }}
</div>
and style them however you prefer.
flash() and response.alerts() also accept category filtering, so you can do:
flash('message1', 'error')
response.alerts(category_filter=["error"])
or you can receive all flash messages with their category:
>>> response.alerts(with_categories=True)
[('error', 'message1')]