I have a view that calls a function to get the response. However, it gives the error View function did not return a response
. How do I fix this?
The following does not return a response:
@app.route('/hello', methods=['GET', 'POST'])
def hello():
hello_world()
You mean to say...
@app.route('/hello', methods=['GET', 'POST'])
def hello():
return hello_world()
Note the addition of return
in this fixed function.
No matter what code executes in a view function, the view must return a value that Flask recognizes as a response. If the function doesn't return anything, that's equivalent to returning None
, which is not a valid response.
In addition to omitting a return
statement completely, another common error is to only return a response in some cases. If your view has different behavior based on an if
or a try
/except
, you need to ensure that every branch returns a response.
This incorrect example doesn't return a response on GET requests, it needs a return statement after the if
:
@app.route("/hello", methods=["GET", "POST"])
def hello():
if request.method == "POST":
return hello_world()
# missing return statement here
This correct example returns a response on success and failure (and logs the failure for debugging):
@app.route("/hello")
def hello():
try:
return database_hello()
except DatabaseError as e:
app.logger.exception(e)
return "Can't say hello."