I have a form with method="get" set on the form. I have a control (DropDownList) with the SelectMethod attribute defined to populate the list's contents. On first load the SelectMethod is called and works (and I can verify this with a breakpoint). However, if I submit the form I can see the browser update and the query string get populated but SelectMethod is not called/I don't hit the breakpoint.
I'm more or less following the example from Microsoft here http://www.asp.net/web-forms/overview/presenting-and-managing-data/model-binding/using-query-string-values-to-retrieve-data
only I'm using a form submission with a GET instead of a link with a mutated query string.
Related
Lets say I have couple of filters in my deployment descriptor and each request to the app has to pass through those. There is form with a formbean attached to it. Once I fill the form and click submit, when does the html parameters in the form are binded to the form bean? Before the request is passed through the filters or after passing thorugh the filters?
The reason I am asking is.. I have a form with 20 fields. Once I click submit, 17 values are being binded to the bean properly but 3 values are missing by the team request reaches validate method. I am absolutely clueless has to where the values are missing. I tried to print an enumeration of all the request parameters in validate method and those three fields are there in request object. AFAIK, There is no issue with those three elements name because the app works perfecly in my local IDE but brakes up in test env which makes it all the more difficult to pin-point the issue :(.
We have an existing Django form that accepts GET requests to allow users to bookmark their resulting query parameters. The form contains many fields, most of which are required. The form uses semi-standard boilerplate for handling the request, substituting GET for POST:
if request.method == 'GET':
form = myForm(request.GET)
if form.isValid()
# Gather fields together into query.
else
form = myForm()
The problem is that the first time the form is loaded, there's nothing in the GET request to populate the required fields with, so most of the form lights up with 'missing field' errors.
Setting initial values doesn't work; apparently, the non-existent values in the GET request override them.
How can we avoid this? I'm pretty certain we're simply not processing things correctly, but I can't find an example of a form that handles GET requests. We want errors to show up if the user hits the "Submit" button while fields are blank or otherwise invalid, but don't want these errors showing up when the form is initially displayed.
The positional argument to the forms.Form subclass informs Django that you intend to process a form rather than just display a blank/default form. Your if request.method == 'GET' isn't making the distinction that you want because regular old web requests by typing a URL in a web browser or clicking a link are also GET requests, so request.method is equal to GET either way.
You need some differentiating mechanism such that you can tell the difference between a form display and a form process.
Ideas:
If your processing is done via. AJAX, you could use if request.is_ajax() as your conditional.
Alternatively, you could include a GET token that signifies that the request is processing. Under this example, first you'd need something in your form:
<input type="hidden" name="action" value="process_form" />
And then you can look for that value in your view:
if 'action' in request.GET and request.GET['action'] == 'process_form':
form = myForm(request.GET)
if form.is_valid():
# form processing code
else:
form = myForm()
I'll also give you the standard, boilerplate point that it's generally preferable not to use GET for form processing if you can help it (precisely because you run into difficulties like this since you're using an anomalous pattern), but if you have a use case where you really need it, then you really need it. You know your needs better than I do. :-)
If your clean page load doesn't have any non form GET params, you can differentiate between a clean page load and a form submit in your view. Instead of the usual
form = YourForm()
if request.POST:
you can do
if request.GET.items():
form = YourForm(request.GET)
if form.is_valid():
...
else:
form = YourForm()
If your clean page load could have other params (eg email link tracking params) you'll need to use the QueryDict methods to test if any of your form params are in the request.
request.GET is and empty dictionary when you first load a clean form. Once you have submitted the form, request.GET will be populated with your fields data, even if the fields contain only empty data.
My first question is this, which I posted as comment:
Why not just use request.POST and the standard way of processing form data?
After considering everything here, perhaps what you are looking for is a way of processing data in your query string to populate a form. You can do that without using request.GET as your form.data.
In my own views, I take advantage of a utility function I created to add initial data to the form from request.GET, but I am not going to share that function here. Here's the signature, though. initial_dict is typically request.GET. model_forms is either a single ModelForm or a list of ModelForm.
def process_initial_data(model_forms, initial_dict):
Nevertheless, I am able to process the form through the standard practice of using request.POST when the form is POSTed. And I don't have to pass around all kinds of information in the URL query string or modify it with JavaScript as the user enters information.
On a webpage we have the following system of server side form validation. For example, if the user is adding date-details for an event (and an event can contain many such date-details), we call a javascript function on click of the 'Add' button like below.
validateForm('frmName','codelibrary/classes/myclass.php','validationArrName')
where:
#frmName = form name
#codelibrary/classes/myclass.php = location of class file, that contains classes and functions for server side validation
#validationArrName = Type of validation we apply
In the php script, validationArrName is defined as a list of keys (representing form fields) and values (representing the functions we will call to validate that form field).
validationArrName = array ('fieldName1'=>validationFun1,'fieldName2'=>validationFun2);
eg:
fieldName1 = email_address
validationFun1 = validateEmail()
On the html page, we call the server side validation through ajax as follows.
$.post(className,$("form[name="+formName+"]").serialize()+"&isValidate=1&validateArrayName="+validateArrayName,function(data){ ... });
If the validation function reports an error, we display an appropriate error message back on the html page.
The problem is that when we do this for the very first time (eg: after a hard refresh of the page), submitting this date-details form for validation takes a lot of time, as compared to subsequent requests.
We observed that instead of calling the codelibrary/classes/myclass.php file once, it actually refers to this file more than 10 times before jumping to the required location (validationArrName) and running that.
For subsequent requests, it works fine and refers to that file only once.
What could be the issue here? Could there be an issue with our usage of jquery submit ?
the best thing you can do is time stuff.
in javascript:
console.time('post load'):
$.post(className,$("form[name="+formName+"]").serialize()+"&isValidate=1&validateArrayName="+validateArrayName,function(data){
console.timeEnd('post load');
console.log('data');
...
});
in php, use microtime to time different part and echo them. they will be printed in the console.
It should not be cache or include related, as ajax starts a new connection each time.
Following your comments, I edit this answer:
I'm still at loss of what happens. However I see two possibilities. The first one is that you use a "flag" to validate forms or not. When you load the page, all forms flag are unset, and first submit check them all. Subsequent submits works correctly.
Another option is that the first time you submit a form, you dont event.preventDefault() on the submit click, but it's still a loosy explanation.
I would love to see how you call the $.post(...) function (how the submit button is binded, or how $().submit() is called).
Suppose I have struts2 select tag in a form, when the form is submitted, according to the validation xml there's an error so input is returned.
Now my question is when input is returned the select box becomes empty. How to prevent it from becoming empty since because in validation error the execution never reaches the action's method (where we can possibly fill the select again).
One possible solution could be to validate the form within the action's method but I want to check the validation through XML only.
I have a hidden input field, which value is read from a property of the request scope:
<h:inputHidden id="myHiddenField" value="#{requestScope['myVar']}" />
I trigger an Ajax-Request where I change the value of myVar.
<p:commandButton value="submit" action="#{myController.doSomething}" update="myHiddenField">
But my input field still contains the old value.
Any idea how I can solve this?
UPDATE:
Maybe I have to explain it a little bit more.. myVar contains the IDs of all input fields with an error message (facesContext.getClientIdsWithMessages()).
When I first submit the form (with some validation errors) it works as expected. When I resubmit the form with some other validation errors the value of myVar doesn't get updated... (Still contains the IDs of the 'old' errors) When I resubmit the form with no validation errors myVar gets updated. (myVar is empty now)
If you want to access a bean after the page has been loaded it needs to be at least ViewScoped. RequestScoped beans are destroyed when the page is loaded (the request is handled and there is no need for it anymore).