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I have a Django webapp displaying a form. One of the fields is a FileField, defined via the Django model of the form:

From models.py:

class Document(models.Model):
    ...
    description = models.CharField(max_length=100, default="")
    document = models.FileField(upload_to="documents/", max_length=500)

The document file_field has an onchange ajax function attached that will parse the uploaded filename, check some database stuff depending on it, and populate other fields on the html-page with the results.

From forms.py:

class DocumentForm(forms.ModelForm):
    class Meta:
        model = Document
        fields = ("document",)

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.fields["customer"] = forms.CharField(initial="", required=True)
        self.fields["output_profile"] = forms.CharField(initial="", required=True)

        self.fields["document"].widget.attrs[
            "onchange"
        ] = "checkFileFunction(this.value, '/ajax/check_file/')"

From urls.py:

urlpatterns = [
    #...
    path("ajax/check_file/", views.check_file, name="ajax_check_file")
]

From views.py:

def check_file(request):

    full_data = {"my_errors": []}
    my_path = pathlib.Path(request.GET.get("file_path").replace("\\", os.sep))
    # parse customer ID from file_path
    # get data of customer from db
    # assemble everything into full_data

    return JsonResponse(full_data)

This is the full html page as displayed (copied from Chrome => show source and cleaned up the indentation & whitespaces some):

<!doctype html>
<html>

    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

        <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
        <link href="/static/css/main.css" rel="stylesheet" type="text/css">
        <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/themes/base/jquery-ui.css"/>
        <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.20/css/dataTables.jqueryui.css"/>

        <script src="/static/js/jquery.js"></script>
        <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
        <script type="text/javascript" src="https://cdn.datatables.net/1.10.20/js/jquery.dataTables.js"></script>
        <script type="text/javascript" src="https://cdn.datatables.net/1.10.20/js/dataTables.jqueryui.js"></script>

        <title>
            Convert RES FILE
        </title>

    </head>


    <body>

        <header id="header">
            <section class="top_menu_left">
                <a href="/accounts/login">Login</a>
                <a>&nbsp|&nbsp</a>
                <a href="/logout">Logout</a>
                <a>&nbsp|&nbsp</a>
                <a href="/edit_profile">Edit User</a>
                <a>&nbsp|&nbsp</a>
                <a href="/register">Register</a>
            </section>

            <section class="top_menu_right">
                <a href="/cartoon">About Us</a>
                <a>&nbsp|&nbsp</a>
                <a href="/contact">Contact Us</a>
                <a>&nbsp|&nbsp</a>
                <a href="/issue">Submit an issue</a>
                <a>&nbsp|&nbsp</a>
                <a href="/documentation">Documentation</a>
                <a>&nbsp|&nbsp</a>
                <a href="/home">Home</a>
            </section>

            <div id="topbanner" >
                <img src="/static/banner_small.png" alt="" width="100%" height="150"/>
            </div>

        </header>

        <aside id="leftsidebar">
            <section class="nav_account">
                <h4>Submit a New Request</h3>
                <ul>
                    <li><a href="/add_submission">Get Typing Results</a></li>
                    <li><a href="/add_comparison">Compare Typing Results</a></li>
                    <li><a href="/convert_typing_format">Convert Typing Format</a></li>
                </ul>
            </section>

            <section class="nav_tools">
                <h4>View Your Requests</h3>
                <ul>
                    <li><a href="/view_submission/?show_all=no">View My Submissions</a></li>
                </ul>
            </section>
        </aside>

        <section id="main">

    <p>&nbsp;</p>
    <h2>Convert Typing Results to Format of Choice</h2>
    <p>&nbsp;</p>

        <h3>Upload a file to our database</h3>
            <form method="post" enctype="multipart/form-data">
                <input type="hidden" name="csrfmiddlewaretoken" value="qqIKcsAynuE35MQ37dvjF5XeIyfcEbHb3wjtgygGZaigQReNxHLQewoDKcEb8Roj">

                <div id="div_id_document" class="form-group">
                    <label for="id_document" class=" requiredField">
                        Document<span class="asteriskField">*</span>
                    </label>

                    <div class="">
                        <input type="file" name="document" onchange="checkFileFunction(this.value, &#x27;/ajax/check_file/&#x27;)" class="clearablefileinput form-control-file" required id="id_document">
                    </div>
                </div>

                <input type="hidden" id="id_description" name="description" value="">

                <p>&nbsp;</p>

                <div id="div_id_customer" class="form-group">
                    <label for="id_customer" class=" requiredField">
                        Customer<span class="asteriskField">*</span>
                    </label>

                    <div class="">
                        <input type="text" name="customer" readonly class="textinput textInput form-control" required id="id_customer">
                    </div>
                </div>

                <div id="div_id_output_profile" class="form-group">
                    <label for="id_output_profile" class=" requiredField">
                        Output profile<span class="asteriskField">*</span>
                    </label>

                <div class="">
                    <input type="text" name="output_profile" readonly class="textinput textInput form-control" required id="id_output_profile">
                </div>

        </div>

        <div class="form-group">
            <div id="div_id_notify_me" class="form-check">
                <input type="checkbox" name="notify_me" style="width:15px;height:15px;" class="checkboxinput form-check-input" id="id_notify_me">
                <label for="id_notify_me" class="form-check-label">
                    Notify me
                </label>
            </div>
        </div>

        <p>
            <button class="linkbutton" type="submit" id="submit_btn">Convert</button>
            &nbsp;
            <button id="create-book" class="linkbutton" type="button" name="button" style="float: right;">Create an Output Profile</button>
        </p>
    </form>


    <div class="modal fade" tabindex="-1" role="dialog" id="modal">
        <div class="modal-dialog modal-lg" role="document">
            <div class="modal-content" id="form-modal-content">
            </div>
        </div>
    </div>

    <div class="modal fade" tabindex="-1" role="dialog" id="modal-check-res-file">
        <div class="modal-dialog" role="document">
            <div class="modal-content" id="form-modal-content-check-res-file">
            </div>
        </div>
    </div>

    <script>
        var formAjaxSubmit = function(form, modal) {
            $(form).on('submit', function (e) {
                e.preventDefault();
                console.log("submitting...");
                var my_val = $("#id_profile_name").val();
                var this_val =  $("#confirm_save").val();
                var res = this_val.split(",");
                var this_val_contains_my_val = (res.indexOf(my_val) > -1);

                if (this_val_contains_my_val === true) {
                    var conf = confirm("Are you sure want to overwrite an exsisting profile?");
                    }else {var conf = true;};
                if (conf === true) {
                $.ajax({
                    type: $(this).attr('method'),
                    url: "/new_customer_profile/",
                    data: $(this).serialize(),
                    success: function (xhr, ajaxOptions, thrownError) {

                        if ( $(xhr).find('.invalid-feedback').length > 0 ) {
                            $(modal).find('.modal-content').html(xhr);
                            formAjaxSubmit(form, modal);
                        } else {
                            $(modal).find('.modal-content').html(xhr);
                        }
                    },
                    error: function (xhr, ajaxOptions, thrownError) {
                    }
                });

                };
            });
        };

        $('#create-book').click(function() {
            console.log("hhallo");
            $('#form-modal-content').load('/new_customer_profile/', function () {
                var iam_alive = document.getElementById("modal");
                // check if iam_alive is defined, this is required if a session expired -> in that case the modal is lost and it would redirect to an almost empty page.
                if (iam_alive) {
                    $('#modal').modal('toggle');
                    formAjaxSubmit('#form-modal-body form', '#modal');
                }
                // if not iam_alive: redirect to login page
                else {
                    window.location.replace('/accounts/login/');
                }
            });
        });


        $('#check-res-file').click(function() {
            console.log("hhallo hier unten jetzt");
            $('#form-modal-content-check-res-file').load('/check_res_file/', function () {
                $('#modal-check-res-file').modal('toggle');
                //formAjaxSubmit('#form-modal-body form', '#modal');
            });
        });
    </script>

    <script type="text/javascript">
        $(document).ready(function() {
            var mycell = document.getElementById("create-book");
            mycell.style.display = "none";
        });
    </script>

    <script>
        function checkFileFunction(myfile, url) {
            $.ajax({                       // initialize an AJAX request
                url: url,                    // set the url of the request (= localhost:8000/hr/ajax/load-cities/)
                data: {"file_path": myfile},
                dataType: 'json',
                success: function (x) {
                    if (x.my_errors.length == 0) {
                        $('#id_customer').val(x.customer_name);
                        $('#id_output_profile').val(x.customer_profile);
                        $('#id_description').val(x.customer_file);
                    }else{
                        $('#id_customer').val("");
                        $('#id_customer').val("");
                        $('#id_output_profile').val("");
                        alert(x.my_errors);
                        var showme = function myFunction() {
                            var mycell = document.getElementById("create-book");
                            mycell.style.display = "block";
                            };
                        showme();
                    }
                    },
            });
        }
    </script>
    </section>
</body>
</html>

Now, I'm trying to test this with pytest via Selenium.

I can send the file path to the field via send_keys(). However, the onchange event seems not to be triggered. (It does work fine when I select the file manually.)

file_field = self.driver.find_element(By.NAME, "document")
file_field.clear()
file_field.send_keys(str(path/to/myfile))

This will register the file fine and it will be uploaded, but the onchange function never happens.

I have searched and it seems others also have encountered the problem of send_keys not triggering the onchange event. But I have not been able to implement any of the suggested solutions in my Python code. (I have not written the Django code for this app, I'm just the tester and my grasp on Django and javascript is not very good, yet. My native programming language is Python.)

The only solution I understood how to implement was sending a TAB or ENTER afterwards (file_field.send_keys(Keys.TAB)) to change the focus, but that triggers an

selenium.common.exceptions.InvalidArgumentException: Message: invalid argument: File not found

(The file I enterted does exist, the path is fine. I can successfully call .exists() on it.)

Simply selecting a different element after send_keys to shift the focus (i.e., customer_field.click()) does not trigger the onchange function of file_field, either.

How can I trigger an onchange event via Selenium from Python? Or otherwise make sure it is triggered?

CodingCat
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  • How are you concluding `onchange` isn't getting fired? – undetected Selenium Jan 21 '22 at 20:16
  • @undetected Selenium I have a function triggered by onchange. It is getting executed when filling the file_field manually, but not when filling it with Selenium. So I conclude that onchange isn't happening. Is there a different explanation? – CodingCat Jan 22 '22 at 09:35
  • @undetectedSelenium You can see the onchange-function in the html code above: `onchange="checkFileFunction(this.value, '/ajax/check_file/')"` Is there a way to explicitly check whether onchange is fired? – CodingCat Jan 24 '22 at 08:44

2 Answers2

2

First of all, your onchange specification is a bit kludgy and would be preferably specified as:

<input type="file" name="document" onchange="checkFileFunction(this.value, '/ajax/check_file/');">

I am using Selenium with the latest version of Chrome and its ChromeDriver under Windows 10 and have no problems with the onchange event being taken. This can be demonstrated with the following HTML document. If the onchange event is taken, then it should create a new div element with id 'result' that will contain the path of the filename selected:

File test.html

<!doctype html>
<html>
<head>
<title>Test</title>
<meta name=viewport content="width=device-width,initial-scale=1">
<meta charset="utf-8">
<script>
function checkFileFunction(value)
{
    const div = document.createElement('div');
    div.setAttribute('id', 'result');
    const content = document.createTextNode(value);
    div.appendChild(content);
    document.body.appendChild(div);
}
</script>
</head>
<body>
<input type="file" name="document" onchange="checkFileFunction(this.value);">
</body>
</html>

Next we have this simple Selenium program that sends a file path to the file input element and then waits for up to 3 seconds (with the call to driver.implicitly_wait(3)) for an element with an id value of 'result' to be found on the current page and then prints out the text value. This element will only exist if the onchange event occurs:

from selenium import webdriver

options = webdriver.ChromeOptions()
options.add_argument("headless")
options.add_experimental_option('excludeSwitches', ['enable-logging'])
driver = webdriver.Chrome(options=options)

try:
    # Wait up to 3 seconds for an element to appear
    driver.implicitly_wait(3)

    driver.get('http://localhost/test.html')

    file_field = driver.find_element_by_name("document")
    file_field.clear()
    file_field.send_keys(r'C:\Util\chromedriver_win32.zip')
    result = driver.find_element_by_id('result')
    print(result.text)
finally:
    driver.quit()

Prints:

C:\Util\chromedriver_win32.zip

Now if your driver is different and that is the reason why the onchange event is not occurring and you do not wish to or cannot switch to the lastest ChromeDriver, then you can manually execute the function specified by the onchange argument. In this version of the HTML file, I have not specified the onchange argument to simulate the situation where specifying it has no effect:

File test.html Version 2

<!doctype html>
<html>
<head>
<title>Test</title>
<meta name=viewport content="width=device-width,initial-scale=1">
<meta charset="utf-8">
<script>
function checkFileFunction(value)
{
    const div = document.createElement('div');
    div.setAttribute('id', 'result');
    const content = document.createTextNode(value);
    div.appendChild(content);
    document.body.appendChild(div);
}
</script>
</head>
<body>
<input type="file" name="document">
</body>
</html>

And the new Selenium code:

from selenium import webdriver

options = webdriver.ChromeOptions()
options.add_argument("headless")
options.add_experimental_option('excludeSwitches', ['enable-logging'])
driver = webdriver.Chrome(options=options)

try:
    # Wait up to 3 seconds for an element to appear
    driver.implicitly_wait(3)

    driver.get('http://localhost/test.html')

    file_field = driver.find_element_by_name("document")
    file_field.clear()
    file_path = r'C:\Util\chromedriver_win32.zip'
    file_field.send_keys(file_path)
    # Force execution of the onchange event function:
    driver.execute_script(f"checkFileFunction('{file_path}');")
    result = driver.find_element_by_id('result')
    print(result.text)
finally:
    driver.quit()

Update

I guess you missed <script src="/static/js/jquery.js"> in the <head> section, which appears to be jQuery. But I would have thought that with this script tag being in the <head> section that jQuery would have to be loaded by time Selenium found the file element. So I confess that your getting a javascript error: $ is not defined is somewhat surprising. I can only suggest now that you try loading it manually as follows as detailed in the code below.

I have re-iterated the 3 things you should try in order in the code below moving on to the next approach if the previous one does not work:

  1. Give jQuery time to load before sending keystrokes to eliminate the $ not defined error.
  2. Manually loading jQuery before sending keystrokes.
  3. Manually executing the checkFileFunction.
# 1. Give jQuery time to load before sending keystrokes:
import time
time.sleep(3)

# 2. if the above sleeping does not work,
# remove the above call to sleep and manually load jQuery.
# Specify where the home page would be loaded from:
document_path = '/home/usr/account/public_html' # for example
jQuery_path = document_path = '/static/js/jQuery.js'
with open(jQuery_path, 'r') as f:
    jQuery_js = f.read()
self.driver.execute_script(jQuery_js)

# Send keystrokes:
file_path = str(path/to/myfile)
file_field.send_keys(file_path)

# 3. Execute the following if the onchange doesn't fire by itself:
self.driver.execute_script(f"checkFileFunction('{file_path}', '/ajax/check_file/');")
Booboo
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  • Thanks for the elaborate answer! I got your test to run fine on my machine. I'm also using the most recent ChromeDriver. So that looks like `onchange` is not actually the problem? Do you have another idea what the problem may be? I have added more of the Django code to my question, maybe this clears something up? – CodingCat Jan 24 '22 at 15:02
  • I have tried adding your last line, but I get a `javascript error: $ is not defined`. – CodingCat Jan 24 '22 at 15:03
  • I am guessing that your **onchange** function uses jQuery. If that is the case then see [my answer here](https://stackoverflow.com/questions/70544340/execute-javascript-using-selenium-in-python#70544798). – Booboo Jan 24 '22 at 15:14
  • The only .js-files contained in this Django app are those contained in the Python packages used. – CodingCat Jan 24 '22 at 15:35
  • Well something is used to implement Ajax fetches. What have you coded in your `checkFileFunction`? And on the client side there are no Python packages, just HTML, JavaScript and CSS. If you use Chrome as a browser you can Inspect the page and see what source and JavaScript files are loaded or just view the page source. Looking at the page source, if you see a reference for the jQuery library following the

    tag, then it is probably not yet loaded by time you have tried executing the `checkFileFunction`, in which case you might want to sleep for a while before you do that. (more...)

    – Booboo Jan 24 '22 at 15:44
  • Sleeping would give a chance for jQuery to finish loading and that one simple change could make everything work including the **onchange** event firing and working as it is supposed to. Just add a `time.sleep(3)` following the `driver.find_element` call and see if it now works. You can then cut back on the sleep time until it stops working. Let me know what happens. – Booboo Jan 24 '22 at 15:46
  • @Bamboo There are no references to jquery in or below the body that I can see. Waiting did not change anything. I have added the full html of the page as retrieved from Chrome in the question above, does that clear up anything? – CodingCat Jan 25 '22 at 09:25
  • I have added an update that reviews and clarifies the steps you should try in order to resolve this including a new step 2. – Booboo Jan 25 '22 at 12:25
  • Ah. I was confused because I couldn't find the jQuery.js file. Apparently, Django creates this under the hood. To make it visible (and before serving on anything not Django itself), one has to call `python manage.py collectstatic` to create that static folder. Then it can be found. Step 2 solved the problem, thank you! – CodingCat Jan 25 '22 at 13:35
  • As it turns out, once the `collectstatic` had run and the `static` folder with the jQuery.js file been constructed, the Selenium test runs fine even without having to call jQuery explicitly. So the whole problem was actually that the Selenium-run test could not see Django's internal `static` folder. Which makes sense, of course, now that I know about it. Thanks for helping me find this! – CodingCat Jan 26 '22 at 08:06
0

As it turns out, the actual problem was that my manual test were done on the Django app served via python manage.py runserver. This calls some hidden Django magic, including collecting the statics files (css, jQuery.js etc.) under the hood.

I now learned that, in order to serve a Django app on a proper server, one needs to first call python manage.py collectstatic. This will generate a static folder in the parent directory, which contains all the static files and also an explicit jQuery.js.

Then, when Selenium is run, it will find that static folder and the jQuery.js file therein. And then, everything works as expected, including onchange.

So the problem was, that this parent static folder was missing, which I never saw because serving the website via python manage.py runserver doesn't need it.

CodingCat
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