Develop Reference

Warn on non-ASCII Characters in Django Form

I'm trying to add some client-side Ajax validation of my Django form. I want to warn users, as they are typing in a field, if any of the characters they just inputted are not ascii.
I originally put the basic python to check for ascii characters in my form's clean method. I don't want to do that, though, as I don't want to produce an error but rather just give a warning message and let the user continue with the rest of the form.
try:
field_value.decode('ascii')
except UnicodeEncodeError:
#raise forms.ValidationError("Non-ASCII characters may cause issues in registering your data. Consider removing these characters. You may still submit at your own risk.")
# Just want to show a warning so the user can still submit the form if they wish
I want to show a small warning under the field as the user is typing. I've tried using django-dajax, but am not sure. How can I do this?
EDIT:
To clarify, I want to show the warning before the user submits the form. So, as they are filling out the form...

Use
> <input type="text" pattern="^[\x20-\x7F]+$" id ....>
in html

Use JavaScript to validate that form field.
Example (using jQuery):
<form>
<input name="whatever" id="fieldId">
...
</form>
<script type="text/javascript">
/* Define a function to check the form field value */
function containsAllAscii(str) {
return /^[\000-\177]*$/.test(str); // returns true if all are ASCII characters. false otherwise.
}
/* Now a little jQuery */
$('#fieldId').on('change', function() {
str = $(this).val();
is_valid = containsAllAscii(str);
if (!is_valid) {
window.alert("There are Non-ASCII characters in the input field");
}
});
</script>
The above code will check the given field's value whenever it changes (i.e. loses focus). You can use .on('keyup', ... instead of .on('change', ... which will check the field's value as the user is typing.
Finally, the error message that is shown is just a browser alert. Which is crappy. You can display a beautiful error message, you just need to learn a little more of jQuery. But I hope I've given you a good starting point.
Credits:
The code for containsAllAscii function is taken from this answer by Juan Mendes.

In your django form, create a custom field and take advantage of the media class.
from django import forms
class MyWidget(forms.TextInput):
class Media:
css = {
'all': ('pretty.css',)
}
js = ('animations.js', 'actions.js')
and set the js to the javascript file you will use for validation. something along the lines of the the other answer
https://docs.djangoproject.com/en/1.9/topics/forms/media/

jQuery validation plugin - how to style 1 validation message differently to others

I have a form that is being validated with the jQuery validation plugin successfully.
Messages are displayed in the correct position and in the correct situations.
So far, so good.
I have 1 field that is being validated correctly, but I need to position that 1 validation message differently to the others. With 2 inputs next to each other, I want the validation to appear under them both (ie under the block that wraps them both) rather than to the right per individual inputs.
The validation on these 2 inputs are dependent on each other, ie at least one must have input. The validation rule works, it's just the positioning I'm struggling with.
I'm using the following validation syntax:
$('#formId').validate({
rules: {
},
messages : {
}
}
In my HTML I have created a label specifically for the (radio) field I am trying to customise:
<label for="radioName" id="radioNameId-invalid" class="error"">Some error message</label>
I tried adding content to the 'showErrors' function of validate, which works, but seemingly then doesn't show any of the other validation messages in my page.
showErrors: function(errors) {
var collectionMethodError = errors['collectionMethod'];
if(collectionMethodError) {
$('#radioNameId-invalid').text(errorString);
$('#radioNameId-invalid').css("display","block");
}
}
I want to enable this error AND then allow validator to continue to do its default behaviour for other fields.
If I remove the showErrors function, the other validation messages are displayed but not my custom one.
How can I get both behaviours?

I ended up using the errorPlacement function instead of the showErrors function:
errorPlacement: function(error, element){
$(error).insertAfter(element);
// special case for display
if($(element).attr("name")=="radioName") {
$(error).insertAfter("#anElement"));
$("label[for=radioName].error").attr("id","invalid-radio-message");
}
}
So in short I'm adding an ID to a label that validation plugin adds, then styling to that ID in my css.
That seems to do what I was trying to do. Now to workout the re-hiding of the message!

How to manually show an HTML validation message from a JavaScript function?

I want to know if there is any way to programmatically show a HTML validation error, using a JavaScript function.
This is useful for scenarios where email duplication has to be checked. For example, a person enters an email, presses the Submit button, and then has to be notified that this email is already registered or something.
I know there are other ways of showing such an error, but I wanted to display it in the same way as how the validation error messages are shown (e.g. invalid email, empty field, etc.).
JSFiddle: http://jsfiddle.net/ahmadka/tjXG3/
HTML Form:
<form>
<input type="email" id="email" placeholder="Enter your email here..." required>
<button type="submit">Submit</button>
</form>
<button id="triggerMsg" onclick="triggerCustomMsg()">Trigger Custom Message</button>
JavaScript:
function triggerCustomMsg()
{
document.getElementById("email").setCustomValidity("This email is already used");
}
The above code sets the custom message, but its not automatically shown. It's only shown when the person presses the submit button or something.

You can now use the HTMLFormElement.reportValidity() method, at the moment it's implemented in most browsers except Internet Explorer (see Browser compatibility at MDN). It reports validity errors without triggering the submit event and they are shown in the same way.

var applicationForm = document.getElementById("applicationForm");
if (applicationForm.checkValidity()) {
applicationForm.submit();
} else {
applicationForm.reportValidity();
}
reportValidity() method will trigger HTML5 validation message.

This question was asked over a year ago, but it's a good question that I recently encountered as well...
My solution was to use JavaScript to create an attribute (I went with "data-invalid") on the <label> of each <input>, <select> and <textarea> containing the validationMessage.
Then some CSS...
label:after {
content: attr(data-invalid);
...
}
... displays the error message.
Limitations
This only works provided each element has a label. It will not work if you put the attribute on the element itself, because <input> elements cannot have :after pseudo elements.
Demo
http://jsfiddle.net/u4ca6kvm/2/

As mentoned by #Diego you can use form.reportValidity();
To support IE and Safari include this polyfill, it just works:
if (!HTMLFormElement.prototype.reportValidity) {
HTMLFormElement.prototype.reportValidity = function() {
if (this.checkValidity()) return true;
var btn = document.createElement('button');
this.appendChild(btn);
btn.click();
this.removeChild(btn);
return false;
}
}

Delete empty values from form's params before submitting it

I have some javascript which catches changes to a form then calls the form's regular submit function. The form is a GET form (for a search) and i have lots of empty attributes come through in the params. What i'd like to do is to delete any empty attributes before submitting, to get a cleaner url: for example, if someone changes the 'subject' select to 'english' i want their search url to be
http://localhost:3000/quizzes?subject=English
rather than
http://localhost:3000/quizzes?term=&subject=English&topic=&age_group_id=&difficulty_id=&made_by=&order=&style=
as it is at the moment. This is just purely for the purpose of having a cleaner and more meaningful url to link to and for people's bookmarks etc. So, what i need is something along these lines, but this isn't right as i'm not editing the actual form but a js object made from the form's params:
quizSearchForm = jQuery("#searchForm");
formParams = quizSearchForm.serializeArray();
//remove any empty fields from the form params before submitting, for a cleaner url
//this won't work as we're not changing the form, just an object made from it.
for (i in formParams) {
if (formParams[i] === null || formParams[i] === "") {
delete formParams[i];
}
}
//submit the form
I think i'm close with this, but i'm missing the step of how to edit the actual form's attributes rather than make another object and edit that.
grateful for any advice - max
EDIT - SOLVED - thanks to the many people who posted about this. Here's what i have, which seems to work perfectly.
function submitSearchForm(){
quizSearchForm = jQuery("#searchForm");
//disable empty fields so they don't clutter up the url
quizSearchForm.find(':input[value=""]').attr('disabled', true);
quizSearchForm.submit();
}

The inputs with attribute disabled set to true won't be submitted with the form. So in one jQuery line:
$(':input[value=""]').attr('disabled', true);

$('form#searchForm').submit(function() {
$(':input', this).each(function() {
this.disabled = !($(this).val());
});
});

You can't do it that way if you call the form's submit method; that will submit the entire form, not the array you've had jQuery create for you.
What you can do is disable the form fields that are empty prior to submitting the form; disabled fields are omitted from form submission. So walk through the form's elements and for each one that's empty, disable it, and then call the submit method on the form. (If its target is another window, you'll then want to go back and re-enable the fields. If its target is the current window, it doesn't matter, the page will be replaced anyway.)

Well one thing you could do would be to disable the empty inputs before calling "serializeArray"
$('#searchForm').find('input, textarea, select').each(function(_, inp) {
if ($(inp).val() === '' || $(inp).val() === null)
inp.disabled = true;
}
});
The "serializeArray()" routine will not include those in its results. Now, you may need to go back and re-enable those if the form post is not going to result in a completely refreshed page.

Maybe some of the proposed solutions worked at the moment the question was made (March 2010) but today, August 2014, the solution of disabling empty inputs is just not working. The disabled fields are sended too in my Google Chrome. However, I tried removing the "name" attribute and it worked fine!
$('form').submit(function(){
$(this).find('input[name], select[name]').each(function(){
if (!$(this).val()){
$(this).removeAttr('name');
}
});
});
Update:
Ok, probably the reason because disabling fields doesn't worked to me is not that something changed since 2010. But still not working in my Google Chrome. I don't know, maybe is just in the linux version. Anyway, I think that removing the name attr is better since, despite what policy takes the browser about disabled fields, there is no way to send the parameters if the name attr is missing. Another advantage is that usually disabling fields implies some style changes, and is not nice to see a style change in the form a second before the form is finally submited.
There is also a drawback, as Max Williams mentioned in the comments, since the remove name attr solution is not toggleable. Here is a way to avoid this problem:
$('form').submit(function(){
$(this).find('input[name], select[name]').each(function(){
if (!$(this).val()){
$(this).data('name', $(this).attr('name'));
$(this).removeAttr('name');
}
});
});
function recoverNames(){
$(this).find('input[name], select[name]').each(function(){
if ($(this).data('name')){
$(this).attr('name', $(this).data('name'));
}
});
}
However, I think this is not a very common case since we are submitting the form so it is assumed that there is no need to recover the missing name attrs.

Your problem helped me figure out my situation, which is a bit different - so maybe someone else can benefit from it. Instead of directly submitting a form, I needed to prevent empty form elements from being collected into a serialized array which is then posted via AJAX.
In my case, I simply needed to loop through the form elements and disable all that were empty, and then collect the leftovers into an array like so:
// Loop through empty fields and disable them to prevent inclusion in array
$('#OptionB input, select').each(function(){
if($(this).val()==''){
$(this).attr('disabled', true);
}
});
// Collect active fields into array to submit
var updateData = $('#OptionB input, select').serializeArray();

Or serialize, clear empty key=value pairs with regex and call window.location:
$("#form").submit( function(e){
e.preventDefault();
//convert form to query string, i.e. a=1&b=&c=, then cleanup with regex
var q = $(this).serialize().replace(/&?[\w\-\d_]+=&|&?[\w\-\d_]+=$/gi,""),
url = this.getAttribute('action')+ (q.length > 0 ? "?"+q : "");
window.location.href = url;
});

Another approach I always recommend is to do that on server side, so you are able to:
Validate the input data correctly
Set default values
Change input values if needed
Have a clean URL or a friendly URL such as "/quizzes/english/level-1/"
Otherwise you will have to deal with text input, select, radio etc...

Is there anyway to disable the client-side validation for dojo date text box?

In my example below I'm using a dijit.form.DateTextBox:
<input type="text" name="startDate" dojoType="dijit.form.DateTextBox" constraints="{datePattern:'MM/dd/yyyy'}" value='<c:out value="${sessionScope.adminMessageForm.startDate}"/>' />
So for example, if the user starts to enter "asdf" into the date the field turns yellow and a popup error message appears saying The value entered is not valid.. Even if I remove the constraints="{datePattern:'MM/dd/yyyy'}" it still validates.
Without going into details as to why, I would like to be able keep the dojoType and still prevent validation in particular circumstances.

Try overriding the validate method in your markup.
This will work (just tested):
<input type="text" name="startDate" dojoType="dijit.form.DateTextBox"
constraints="{datePattern:'MM/dd/yyyy'}"
value='<c:out value="${sessionScope.adminMessageForm.startDate}"/>'
validate='return true;'
/>

My only suggestion is to programmatically remove the dojoType on the server-side or client-side. It is not possible to keep the dojoType and not have it validate. Unless you create your own type that has you logic in it.

I had a similar problem, where the ValidationTextBox met all my needs but it was necessary to disable the validation routines until after the user had first pressed Submit.
My solution was to clone this into a ValidationConditionalTextBox with a couple new methods:
enableValidator:function() {
this.validatorOn = true;
},
disableValidator: function() {
this.validatorOn = false;
},
Then -- in the validator:function() I added a single check:
if (this.validatorOn)
{ ... }
Fairly straightforward, my default value for validatorOn is false (this appears right at the top of the javascript). When my form submits, simply call enableValidator(). You can view the full JavaScript here:
http://lilawnsprinklers.com/js/dijit/form/ValidationTextBox.js