I'm working on a project that the web page will fetch the data from java hashtable object in jsp page. I'm using a jsp for gerenated the web page based on HTML. The data is stored in the java hasbtable object on the server. I want to try to make an AJAX call to fetch the data from the server, then display it in the jsp page.
I just want to know if this is possible to do that by make an AJAX call to access the java hashtable object, then fetch the data back to the client side.
Thanks
Here is the test.jsp page which contain the hashtable obejcts:
Hashtable generalTable = (Hashtable) metaDataTable.get("General");
Hashtable adminTable = (Hashtable) metaDataTable.get("Administration");
My inital approach is to make an AJAX call to this test.jsp page. Then try to access those two GeneralTable and adminTable hashtable objects. In those two obejcts, it contains the values I would like to fetch.
Unfortunately, I don't have the code yet for my part because I don't know if this is possible or not.
Yes, it's possible, but you will need to have some server-side code to deal wit the request for the data you want, just like with any other AJAX functionality in any other system.
One way to do this would be to have a "special" jsp that gives you back the data you need without any of the typical HTML. Having the special jsp output it's data as a JSON object will make your life much easier in the client-side code.
Related
I have read a lot of answers relating to how to dynamically add forms to an model formset in Django and can successfully implement that. However, I would now like to submit the formset with AJAX. This is mostly working now but I have an issue that I can't find a solution to in any other answer:
If you dynamically add a form to the formset, you give it a new form id number that is one larger than the maximum the form currently has and you also increment the management TOTAL_FORMS count by one. The newly added form then saves successfully as a new object.
I am trying to submit by AJAX so the user can continue editing without having the page refresh. The formset saves fine but any dynamically added forms are now existing objects. To account for this I need to increment the INITIAL_FORMS count on the management form when the save is successful. Easy enough. However, I've also realised I need to give the newly created objects an ID since they now exist in the database.
How can I get my view to tell me the ID of the new objects in its response to the AJAX call? Or is there a better way of looking at this?
Django forms and formsets are intended for classic browser-based posting of data. Though they can definitely be made to work with Javascript, the more you want to part from the normal behavior, the more complex it gets.
Depending on your requirements, you might start thinking about dropping it and switch to Javascript + REST endpoint. Of course, if you need progressive enhancements and you are required to have it work without javascript, that's not an option.
In any case, you want to have a customized view for posting from JS, so that you can get the result back and parse it easily in your AJAX handler. Probably some JSON.
There are several approaches you could take.
Have your AJAX send data to a different URL. This is pertinent if you have an API or are planning to build one at some point. So your form, when submitted normally, will do its old-style processing but your AJAX will talk to the API endpoint instead.
For instance, your form send to https://example.com/myform, but your Javascript code talks to REST api at https://example.com/api/v1/mymodel/ (sending PUT, POST and DELETE requests as appropriate).
Or if you don't have an API and building one seems overkill, you may just alter your view so it formats its output differently depending on whether the data is being submitted in the regular way or using AJAX.
You'd go about it like this:
class MyFormView(.....):
def render_to_response(self, context, **kwargs):
if self.request.is_ajax():
return self.render_to_json(context, **kwargs)
return super().render_to_response(context, **kwargs)
def render_to_json(context, **kwargs):
data = {
# see below!
}
return HttpResponse(
content=json.dumps(data).encode('ascii'),
content_type='application/json',
)
This is just an outline. You need to ensure is_ajax will detect it properly (see django doc). And you need to properly build data from context: extract the things you want to send back to your JS code and put them in the dict.
You will find it's manageable if you just do this for one, maybe two views in your project, but very quickly you'll want to have a small API instead, especially given how easy it is to build one with packages such as Django REST framework.
In your view, where you save the object, AFTER the save, the object.id will contain the new id for the object, which you can return via json or however you want in your ajax response, and then yes you will need to fill that into the formset row so that it will be submitted the next time.
One thing you have to watch out for is that django expects all existing rows to be at the top of the formset, and any new rows to be at the bottom. Otherwise, the formset save will complain about missing id's. So if you're doing any kind of sorting in your javascript, you can't do that.. unless you do quite a bit of fixing of all the field names etc in the formset. The formset code uses the numbers in the management form to determine which rows to insert and which rows to update, it does not do it on the basis of whether or not an id is present. Unfortunately...
I am using dajax for ajax in my django app.
After getting some data from database I create list of <li> elements in my python ajax.py and assign it with dajax to inner html of some container. Like this:
#dajaxice_register
def get_transactions(request):
dajax = Dajax()
transactions = get_transactions()
dajax.assign('#transactions', 'innerHTML', ''.join(transactions))
return dajax.json()
What is considered best practice? Returning html from server or returning json and then creating html in script?
I would return JSON from the server and bind that to the DOM using JavaScript. That way you're keeping concerns separate, and also returning the minimum amount of data from the server.
Always returning JSON helps to create a services oriented architecture with a good separation between your view and your controller (and model).
With this approach, you can have a pure-HTML UI and a REST API to retrieve datas from server.
I think it's a good practice, but it's probably better for Web Application and not for generic websites.
Hi I have four JSP file say one.jsp, tow.jsp, three.jsp and four.jsp
each file has next and previous link to navigate to the all jsp's and last jsp file that is four.jsp has submit button. Now I want values of all fields from first three jsp's into the fourth one, to submit data into DB when the use hit the submit button from four.jsp
I do not have to use the hidden fields to pass the values from jsp to jsp and I don't want to use the session to store the data. Is there any way to pass the data(VO) from one jsp to another without using hidden fields and session?
NOTE : I am using spring. and I am not interested in JSF for navigation.
So you need a stateful bean, might want to look into something like Spring Web Flow. It was made for handling this sort of stuff.
If you don't want to store it in the session, you would have to start looking into EJB which has stateful possibilities.
Here's some documentation:
http://static.springsource.org/spring/docs/2.5.6/reference/ejb.html
P.S. EJB stores stuff in the session as well, don't think there's any getting around it, unless you serialize the POJO and store it as a cookie.
I want to change the list of available values in a dropdown depending on the value selected in another dropdown and depending on values of certain fields in the model. I want to use JQuery to do this. The only hard part is checking the values in the model. I have been informed that I can do this using Ajax. Does anyone have any idea how I will approach doing this?
AJAX is indeed the technology your looking for. It is used to sent an asynchronous request from the client browser to the server.
jQuery has an ajax function that you can use to start such a request. In your controller you can have a regular method tagged with the [HttpPostAttribute] to respond to your AJAX request.
Most of the time you will return a JSON result from your Controller to your view. Think of JSON as something similar to XML but easier to work with from a browser. The browser will receive the JSON and can then parse the results to do something like showing a message or replacing some HTML in the browser.
Here you can find a nice example of how to use it all together.
I'm new in Spring MVC, I just started my first project and I'm doing some research to be sure to set it up in a proper way (should work in the long-term!).
I already know that for a part of the project, I will need to manually change small fragments of the page through Ajax. I know it's possible to change part of the page (using Tiles). What I really need, though, is for example to change a single line in a table containing dynamically generated data (i.e. data coming from the database).
Can you suggest anything?
I don't want to use JSF or Spring JS.
Thank you.
You have at least two choices:
render on the server, send the update html snippet to the brower and use JavaScript to replace them
send an AJAX request to the server, but this time return only the data (JSON) and the "render" the table line in the browser (or just update some pices of text)
For the fist choice you need a dedicated jsp file (and tiles configuration) to render only a single line. As fare as I know, there is no technical support.
What you can do, to reduce the amount of duplicated code is to use that single line rendering jsp in like in include in the one that renders the complete table.
Of course instead of using JSP to render the single line you can also use the Java Method that handles the request, and make it returning the html string.