use many submit buttons in the same form

Question

I cannot access all the buttons from the frame. It is works only with the Histogram button.Here is my form which I want to access it in the Post method.

 <form id="package_form" action="" method="post">
      <div class="panel-body">
          <input type ="submit" name="Download" value="Download">
      </div>
      <div class="panel-body">
          <input type ="submit" name="Histogram" value="Histogram">
      </div>
      <div class="panel-body">
           <input type ="submit" name="Search" value="Search">
      </div>

 </form>

Here is my python code.

 if request.method == 'GET':
        return render_template("preview.html", link=link1)
    elif request.method == 'POST':
        if request.form['Histogram'] == 'Histogram':
            gray_img = cv2.imread(link2,cv2.IMREAD_GRAYSCALE)
            cv2.imshow('GoldenGate', gray_img)
            hist = cv2.calcHist([gray_img], [0], None, [256], [0, 256])
            plt.hist(gray_img.ravel(), 256, [0, 256])
            plt.xlabel('Pixel Intensity Values')
            plt.ylabel('Frequency')
            plt.title('Histogram for gray scale picture')
            plt.show()
            return render_template("preview.html", link=link1)

        elif request.form.get['Download'] == 'Download':
            response = make_response(link2)
            response.headers["Content-Disposition"] = "attachment; filename=link.txt"
            return response
        elif request.form.get['Search'] == 'Search':
            return link1

What I am doing wrong?

Answer 1

It won't work the way you've written it. Only the submit button you send will be included in request.form, you'll get an error if you try to use the name of one of the other buttons.

Also, request.form.get is a function, not a dictionary. You can use request.form.get("Histogram") -- this will return the value of the Histogram button if it was used, otherwise it will return None.

Instead of giving the buttons different names, use the same name but different values.

<form id="package_form" action="" method="post">
      <div class="panel-body">
          <input type ="submit" name="action" value="Download">
      </div>
      <div class="panel-body">
          <input type ="submit" name="action" value="Histogram">
      </div>
      <div class="panel-body">
          <input type ="submit" name="action" value="Search">
      </div>

 </form>

Then your Python code can be:

if request.form['action'] == 'Download':
    ...
elif request.form['action'] == 'Histogram':
    ...
elif request.form['action'] == 'Search':
    ...
else:
    ... // Report bad parameter

Answer 2

Although using the same name for different submits can work (as suggested in the previous answer), it can be not so convenient for i18n.

You can still use different names, but you should check handle them differently:

if 'Download' in request.form:
    ...
elif 'Histogram' in request.form:
    ...
elif 'Search' in request.form:
    ...
else:
    ... // Report bad parameter