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pythonflaskget

I want a GET method sent to Flask view, but I not able to process it. Could anyone offer me some insight into what I am doing wrong?

In my program, I have a GET request sent from a form, to a Flask View.

This is the form:

<form method="GET" action="{{url_for('rerouter')}}">
            {{ form.hidden_tag() }}
            <fieldset class="form-group">
                <legend class="border-bottom mb-4">Search</legend>

                <div>
                    {{ form.welder_selector.label(class="form-control-label") }}
                    {{ form.welder_selector(class="searchable-welder-js",style="width: 28%") }}

                    {{ form.wps_selector.label(class="form-control-label") }}
                    {{ form.wps_selector(class="searchable-wps-js",style="width: 27.8%") }}

                    {{ form.process_selector.label(class="form-control-label") }}
                    {{ form.process_selector(class="searchable-process-js",style="width: 27.8%") }}
                </div>


            </fieldset>
            <div class="form-group">
                 {{ form.submit(class='btn btn-outline-success') }}
            </div>

        </form>

The form method I have set as GET and action also is sent to the view:

The corresponding view:

@app.route("/rerouter", methods=['GET', 'POST'])
def rerouter():

    if request.method == 'GET':
        value1 = request.args.get('welder_selector')
        value2 = request.args.get('wps_selector')
        value3 = request.args.get('process_selector')

        print("Im at rerouter with : ", value1, value2, value3)
        if value1 is not 0 or None:
            if value2 is 0 or None:
                if value3 is 0 or None:

                    return redirect(url_for('welderdatabase', welder_id=value1))
                else:

                    return redirect(url_for('home'))
          ....

The HTML form is made here in this view : 

@app.route("/", methods=['GET', 'POST'])
@app.route("/home", methods=['GET', 'POST'])
def home():

    form = TrialSearchMultipleForm()

    return render_template('home.html', title='Home', form=form)

I have successfully implemented the program using POST method, but I have later learnt that the right way is to use GET for sending form data.

What I caught in the console

127.0.0.1 - - [29/Apr/2019 09:10:20] "GET /rerouter?welder_selector=__None&wps_selector=__None&process_selector=__None&submit=Search HTTP/1.1" 302 
Im at rerouter with :  __None __None __None

So exactly what I'm looking for is :

  1. I am not able to understand why it returns '__None'. I want some insight into why it returns '__None' in the GET request and not 'None'. I tried searching high and low for answers.
  2. The program sends the data but its not redirected to any page, just reloads at home page view. I get the request via the console, so I know the data is being sent.

How do I solve this ?

  1. I have tried disabling CSRF just to see if __None will change to None. No success there.
  2. I sort of understand that the GET request is sent as a string, and hence that might be a reason for __None, but how do I circumvent this and get the desired output?

Expected Result :

Im at rerouter with : None None None or Im at rerouter with : 1 None None (based on the input)

And successful redirection to the page using the conditions. My code is not that clean because this section of the program was constantly changing and I needed to keep everything short, so please bear with me.

I'll be extremely grateful for ANY pointers or suggestions or helpful tips.

Solution

  • Don't know if it will solve your problem - just taking a cursory glance at your python script.

    if value1 is not 0 or None:

    This isn't doing what you think it's doing. 'None' is considered falsey. What you've written is equivalent to the following two independent boolean expressions:

    if (value1 is not 0) or (False):

    Therefore, the only part of that expression that has any bearing on whether the body of the if-statement is executed is the first part (value1 is not 0). This means that your if-statement's body will not be executed if value1 is None, should that ever be the case.

    In addition, assuming that's fixed, you probably don't want to separate the two conditions with an 'or'. It seems to me that value1 must not be either of those values, in which case you would use 'and'.

    Incidentally, this may not be so critical, but I would check whether value1 is not equal to the value zero, instead of checking whether their identities are not the same.

    According to pep8, however, when one is checking if something is None, one should prefer (value1 is not None) over (value1 != None). The fixed condition would look like this, in my eyes:

    if value1 != 0 and value1 is not None: