CODEWITHSUNDEEP
pythonflask
Egor Maksimov
Egor Maksimov

Reputation: 62

Flask: call function with parameters from form action

in routes.py I have a function:

@app.route('/')
@app.route('/makecsc_relocation') 
def makecsc_relocation(csc_post_index):
    ... 
    makeCscRelocationRep(repname, csc_post_index)
    return send_file(repname+'.xlsx', as_attachment=True, attachment_filename=repname+' '+csc_post_index+'.xlsx')

in index, I have the following:

@app.route('/')
@app.route('/index')
def index():
...
sForm = """<form action="makecsc_relocation">
                             Enter postal code here: <input type="text" name="post_index" value=""><br>
                             <input type="submit" value="Download report" ><br>
                             </form>"""

If I use function that has no parameters in <form action=""> and pass to it an empty input value, everything works fine, but as I tried to pass input post_index as an argument to that function, I get Internal Server Error with following URL: http://myservername/makecsc_relocation?post_index=452680

How do I fix that?

Upvotes: 0

Views: 4353

Answers (2)

Egor Maksimov
Egor Maksimov

Reputation: 62

I ended up with the following solution:

  1. Added POST method to the form
sForm = """<form action="makecsc_relocation" method="post">
                             Enter postal code here: <input type="text" name="post_index" value=""><br>
                             <input type="submit" value="Download report" ><br>
                             </form>"""
  1. In function makecsc_relocation, I added following string:
csc_post_index = request.form['post_index']

and passed that to makeCscRelocationRep

Upvotes: 0

Martijn Pieters
Martijn Pieters

Reputation: 1125308

Function parameters are always path parameters, the <parametername> components in the route path you register with @app.route(). You don't have such parameters, so don't give your function any parameters. See Variable Rules in the Flask Quickstart.

Query parameters (the key=value pairs from a form, put after the ? in the URL) end up in request.args:

@app.route('/makecsc_relocation') 
def makecsc_relocation():
    csc_post_index = request.args.get('post_index')  # can return None
    # ... 
    makeCscRelocationRep(repname, csc_post_index)
    return send_file(repname+'.xlsx', as_attachment=True, attachment_filename=repname+' '+csc_post_index+'.xlsx')

See The Request Object section of the Quickstart.

  • Use request.args.get(...) if a value is optional, or if you need to convert it from a string to a different type at the same type.
  • Use request.args[...] if it is an error to not provide the value. If the query parameter is missing, a 400 Bad Request HTTP error response is given to the client.

See the Werkzeug MultiDict documentation on how this mapping works in detail.

Upvotes: 1

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