<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>

@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'))
          ....

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

    form = TrialSearchMultipleForm()

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

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

if value1 is not 0 or None: