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.
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...
Is there another way to view the profiling results of MiniProfiler (I'm specifically interested in EF5 version)?
Every tutorial that I've seen uses MiniProfiler.RenderIncludes(); but since my MVC app mostly returns JSON, that is not an option for me.
Is there a way to write results to file or something like that?
You can read and write results to just about anywhere by changing the MiniProfiler.Settings.Storage to a different IStorage implementation from the default (which stores to http cache). If you wanted to, this could store to and read from a file pretty easily (you would have to write your own custom implementation for that).
The files served by RenderIncludes are the html templates for displaying the results and the script to retrieve the results from the server and render them on the client (all found here). But you are by no means obliged to use this mechanism. If you want to write your own logic for retrieving and displaying results, you should base this off of the logic found in MiniProfilerHandler.GetSingleProfilerResult. This function roughly performs the following (putting in the siginificant steps for your purposes):
Gets Id of next results to retrieve (through MiniProfiler.Settings.Storage.List())
Retrieves the actual results (MiniProfiler.Settings.Storage.Load(id))
Marks the results as viewed so that they wont be retrieved again (MiniProfiler.Settings.Storage.SetViewed(user, id))
Converts these to ResultsJson and returns it
With access to MiniProfiler.Settings.Storage, you should be able to retrieve, serve and consume the profile results in any way that you want. And if you are interested in using the RenderIncludes engine but want to mess around with the html/js being served, you can provide your own custom ui templates that will replace the default behavior.
I would develop my CakePHP application in the most reusable way. I'd like to treat it as webservices, so I don't want to strictly bind controller with view. My idea is: controller just returns json info, the view calls the controller and get the json and make html output.
How can I realize that? Could be a good approch, developing pages rather than views, and inside that pages call the webservices previously developed.
You can even forget about creating view files, using $this->set('_serialize', array('people')); in your PeopleController::show()
Well Cake is kinda' works like this "out of the box". You can use Router::parseExtensions(); to define what type of data you would like to serve. For example in app/Config/routes.php:
Router::parseExtensions('xml','json');
This will make it possible to detect what kind of request is incoming. For example if someone requests:
www.example.com/people/list.json or www.example.com/people/list.xml, in your PeopleController's list() method you'd be able to detect what kind of resource is being requested - json or xml, or of course any other
extension you define. This is what the RequestHandlerComponent is used for. You can check if it is xml for example:
if($this->RequestHandler->isXml()) {
//Some code
}
The different extensions are only different representation of the data, so it shouldn't matter what exactly you're serving. From v2.1 Cake will automatically switch the view class when it sees a JSON or XML request, which takes us to the new JSON and XML views.
All you will have to do is provide the views in the appropriate places.
In View/People (as for this example) you would have:
..View/People/
list.ctp
xml/
list.ctp - XML view
json/
list.ctp - JSON view
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'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.