I'm creating a pager for grid data. Basically, I can do it in two ways: when user clicks on a page number, load grid data by using ajax call, or, post back to server (GET or POST) and use query string parameters (or POST variables) to know which page to display. With both methods, sorting of grid items must be persisted.
What is better considering performance and SEO and why?
-- UPDATE --
I need pros and cons for both approaches. I know this is somewhat discussion rather than question, but I need your experiences.
Also, when using ajax, it is not only SEO that I'm wondering about. Will browser's back button behave as expected?
Why not do both.
Have the grid load with SEO friendly anchor GET links then implement some JavaScript to convert them to AJAX calls.
People without JavaScipt (like spiders) can then still navigate around while fancy people will get the enhanced AJAX experience.
With AJAX you can alter history and make the back button work as expected.
Your grids are loaded via AJAX? and you are worried that SEs won't pick them up?
What you can do to get your content indexed is to:
use segmented URLS like CodeIgniter and WordPress instead of query strings. SEs will (supposedly) see them as subfolders.
Instead of loading everything in AJAX, grid data can also be represented as tabular data. What you can do is to load the tabular format for the static page, then with JS, you can replace the table with your grid.
say for example i want to load sports stats, mysite.com/sports/stats should give me tabular data when JS is off, and if i had JS, that data is replaced with the grid.
Related
My current setup looks like this(from here, mostly):
This is the result of my home view. What I intend on doing is keep those 2 sidebars in place and refresh only the content part.
My question: What is the obvious solution to this in django?
From what I read so far it seems to be using Ajax to see what exactly the user clicks on the sidebars and return only a part of the HTML which would be the div where all the content is. (or return a JSON and refresh that div depending on the JSON values?)
I need to avoid refreshing the entire page, it seems useless. I could forget about Ajax and just run on separate views but I would have to pass every time a context variable to populate the sidebars depending on the user and this seems to be an overkill.
Even more specific: On the push of a button on the navbar now that is a href- links to another page. In order to make it refresh only part of the page what should the button trigger? Should it trigger a jquery function or is there a better option?
If your concern is only about left sidebar calculations, then you can go with caching
Django allows to cache part of page - sidebar is ideal item for caching. If sidebar is different for users (I see at least playlists menu item), then it's also possible to implement fragment caching per user, check Vary on headers part of documentation.
Using ajax will complicate your development process - generate html/json encode/render it on user side, etc, etc. And now almost no one uses django in this way. If you want pure single page application, then I suggest you to take a look at some javascript framework like Angular, Vue or React + Django API backend.
I have various tables with the following size : 12 columns and up to 1800 rows. It takes 8 seconds to render it to the user. I currently use h:dataTable. I tried ui:repeat to get the row data from a Java List object, managed by JSF. Although this works fine, the 8 seconds to render the table is unacceptable. I'm trying to find other ways to do this, but need to keep JSF as my controller for action buttons on the page. In other words I want to create the 'table markupto send to thepage myselfand then still associate actions onh:commandButtons` to the managed bean methods. Is there a way to do this?
The only ways I can think of is to use jquery or ajax to create the table markup, although I am new to technologies other than JSF for UI development.Maybe then I would somehow pass that to the client for render. The only problem is I don't know how to generate the markup from my list, and second how I would inject it between h:commandButtons that are in my XHTML file currently.
Does any one know how I can solve this without having to completely rip OFF JSF? One main problem I have is that the business requirement that says we can't page the datatable (i.e: Next / Back buttons displaying 100 at a time for example). So, possibly I was thinking I could do this by Ajax calls to the server and get 100 rows at a time after page ready, and append new rows behind the scenes to the user. This would be a "perceived" speed of load, but I don't know how to do this at all.
8 seconds isn't bad for a whopping 1800 rows on 12 columns. 10~100 rows is done in less than a second, right?
Before continuing with this, are you absolutely positive that all those 1800 rows are supposed to be shown at once? Isn't this very user unfriendly? Wouldn't the user have to need Ctrl+F to find the information it is looking for? Isn't that annoying? Why don't you introduce filtering (a search field) and pagination exactly like as Google is doing to present the zillion of results in a sane and user friendly manner?
Anyway, you could consider using "On-Demand data" option of PrimeFaces <p:dataTable>, wherein the data is loaded by ajax during scrolling via <p:dataTable liveScroll="true">. See also the showcase example. No homegrown code nor manually fiddling with jQuery necessary. PrimeFaces has done it all under the covers.
It you don't want to use PrimeFaces for some reason, then you could consider using OmniFaces <o:componentIdParam> in combination with some jQuery "live scrolling" plugin. See also the last example in its (snapshot) showcase page for a kickoff example (which should easily be adapted to be triggered by hitting the scroll bottom instead of by clicking).
I have a dropdown, that contains some list of StudentCode...
when user select any studentcode student data should be displayed in form with student's Image...
for displaying Student Image, Im putting student image in cache memory... and I have one Iframe that gets the byte data from cache memory and render that image on my page... problem is... this thing need at least 1 postback...
can I make some partial postback to render this image?
I see couple problems with the implementation.
1) You should avoid using IFrames in general as there are better ways of handling rendering parts of the webpage.
2) Storing images in cache means that you actually downloaded all of them for each Student in the dropdown list and placed them in the cache. What if there are 100 students? Getting images for all of them and storing them might take a lot of resources.
I suggest you to do the autopostback on dropdown selected value change (via ajax call) which calls a method that will return a partial view with all the information you need for the particular student, including the image.
I found using Ajaxify library (http://max.jsrhost.com/ajaxify/) very easy and convenient for ajax calls.
You can do the same thing without ajax at all in which case the whole page will reload with the same result.
I have some view (Views 2 - list of invitations, table style) which uses embedded forms to edit records directly in view rows.
I am using ahah to change values in records. What I need is to refresh all records dynamically (some calculations) after I change some checkboxes.
Is there any way to refresh view using Ajax?
To trigger reload table rows only form the code?
I suspect it must be some way (some command) as there is a Use Ajax option in views for sorting tables, etc...
Any hints would be much appreciated
In basic settings there is the 'use ajax' option which :
If set, this view will use an AJAX mechanism for paging, table sorting and exposed filters. This means the entire page will not refresh. It is not recommended that you use this if this view is the main content of the page as it will prevent deep linking to specific pages, but it is very useful for side content.
you may find the module Ajax Views Refresh useful
i am asking myself if it is possible to somehow create a dynamic gui in jsp. So that i could have something like a dropdown menue for the country and based on what i have selected in that window a dropdown menue for cities, without reloading the jsp page. Or, in a dialog with multiple input lines, to be able to add an additional line with a button, again without reloading the whole page. In the first case the cities information would be in a database, in the second the information provided would be stored at the end in a database, so i cant just use java script (and don't really want to).
At a minimum, you would need to utilize JavaScript to implement what you want. Most would implement it the way Tim describes in his first paragraph.
Set up two .JSP's:
The first contains your main form with the country drop-down menu. Some JavaScript on the first .JSP triggers an AJAX request to a second .JSP. The second .JSP accepts a country-ID parameter and uses a servlet to query your DB for a list of cities, then renders that data. Once the request returns, the JavaScript in your first .JSP inserts the list of cities into a new drop-down menu.
This may seem complex, but several JavaScript libraries exist to assist you with this task. Look into jQuery or Dojo.
To update the page without posting back the whole page, the browser would use ajax. Using a database does not eliminate ajax. Ajax calls server code that digs your data out of the database.
Regardless, to do what you want, without writing your own javascript, look at GWT (Google Web Toolkit). You right ajax applications in Java that generates the javascript for you.