I'm running an e-commerce website and many pages are dynamic but for a widget displaying the number of items in the visitor's cart. I want to cache the page yet retain this dynamism. I'm considering caching the fragments before and after this widget but I was wondering if there was a simpler way to get this done.
Edit: Perhaps something which decided to give the cached page or not depending on whether the cart was empty or not would be a good start.
Kindest of Regards,
-- Jack
One way to do it is have the cart items displayed using JavaScript that's inserted after the page is loaded. You can see this on places like StackOverflow where your login status gets injected into the page if it wasn't already cached. jQuery can make this pretty straightforward.
You can set the number of items in a cookie accessible to JavaScript, not in the session hash as that's not exposed to the client, and handle that in the document.onload section.
Related
I am developing an ASP.NET MVC 4 application using jquery.tablesorter.js, jquery.tablesorter.pager.js and jquery.tablesorter.widget.js. Now I get an issue with this tablesorter, that is, the page number is saved in the local storage.
I understand it is saved for some reasons. The problem is, for example, I last open the 3rd page of the table and leave the session, then re-open a session, it goes to the 3rd page automatically. If, for some reasons, there is not enough items for any item to go to the 3rd page, it simply shows an empty table and pager, and confuses the user.
Any idea is highly appreciated.
Thanks,
A. Zhang
If you don't want the pager to save the page & size, then set the savePages option to false.
If you do want the page to get saved, but you only want to use session storage, then set the storage_useSessionStorage widget option to true.
Please note: the above options only work with my fork of tablesorter.
I am trying to convert my asp.net mvc4 app, which had fairly heavy use of SessionState, into a stateless app. I understand that I can store this information in the DB, and intend to do so.
My question, though, is about my particular architecture. My app has a main 'page' consisting of a number of partial view panels, which each have actions in them that can affect the other panels. What i've been doing up to now is storing the entire state of the viewModel (lots of inter-related EF list collections and 'record' objects) in the session, and its been working great. Except when the session just randomly dies.
So, I need to get this data out of the session, and into the DB where I can rebuild the thing at need. My concern is that, if I store the info in the database, every single action done on screen might affect 3-5 different panels, each with their own State updates, thats a minimum of 10 round trips to the DB for every interaction!
What are some strategies I can use to make this idea more scalable?
EXTRA INFO
The view in question here is a sort of POS shopping cart system. There are panels for selecting events, selecting/adding items to the cart, editing cart items, selecting contacts, editing contacts, displaying the cart items, displaying the cart 'subtotals', and finally, a panel with a [checkout] button.
Selecting a new event will change the list of available items. Selecting an item to add to the cart will change the cart item list, subtotals, as well as the checkout panel. Same for editing a cart item.
The main concern is how to recover from a lost session, as I've found the built-in asp.net session code too unreliable. My testers have encountered issues with sessions timing out, and then my app not having any kind of recovery process. When its installed on 1500 sites, each with an average of 10 users, its going to be a plague of lost session issues, and I need to combat that before it becomes a real problem.
I agree that I'm not going stateless...wrong choice of words used in a rush. I'm just trying to move that state into a form that I can rely on past the session failure. My main idea presently is to continue using the session as the local cache for the viewModel data, but to have a fallback operation that can rebuild the viewModel from DB if the session one is lost somehow.
You shouldn't necessarily be using a database to store (what sounds like) data that only needs to be persisted in the short term.
If these changes to the other partials are only relevant in the context of the current "master view," then I would suggest using jQuery AJAX to send off the requests, parse the response JSON and update the other views. Tutorials on jQuery AJAX and ASP.NET MVC are easy to find, if you don't already have the knowledge:
http://www.codeproject.com/Articles/41828/JQuery-AJAX-with-ASP-NET-MVC
This way, you don't need to make a bunch of round trips. If the changes need to be persisted beyond the context of the current view, make ONE round trip to the database to perform the update and then simply update all of the other partials from the in-memory response from the AJAX call.
You don't need to read from secondary storage multiple times when you already have all of the information you need in-memory. Just do the reading and writing once.
I decided to go with a hybrid approach. I'm still using session, but I'm building out a DB 'recovery' option, so that if the session portion is lost, the DB will be able to provide the values needed to rebuild the session seamlessly.
Seems to be working well, so far.
I have a rails app that shows users posts. Users posts can be sorted in many ways, paginated, categorized, etc. I am doing all of these clicks over ajax.
However, everytime I click a category or a sortby param or a new page, it loads the ENTIRE request again and then returns it in the way specified. Is there any way to cache my first results and THEN sort, paginate, categorize quickly?
In order to enhance the performance, a better way is to use memcache. If you have memcache installed and implemented in your rails app, you can cache that query for a certain period of time without actually querying the database again instead it will fetch directly from memory again, thus it improved performance greatly. You may want to check out https://github.com/nkallen/cache-money.
This is a question of using AJAX vs a non-AJAX javascript implementation.
When using Ajax, the question you should ask yourself is, does this action require more information or logic from the server? If the answer is no and you can do it using only the information you have already loaded on the client browser, you should try and implement it using Javascript.
In this case, there are plenty of solutions for javascript sorting out there. For example, if you want a simple table-like sorting (your table could be invisible) you could use something like this plugin: http://yoast.com/articles/sortable-table/
If you're looking for a more custom solution, you could write the javascript by hand, this post: Sort <div> elements using jQuery gives a good starting point.
Hope that helps!
Im using MVC ASP.NET C#, jQuery
I'm building what could be decribed as the simpliest shopping cart in the world.
Basically My Clients wants users to be able to browse the site, Click on a product they want and it be added to a "list" and then when they "Checkout" they simply fill in a form and it emails my client with the list of products they had chosen!
I was thinking of something like storing them in a cookie. So as the user browses they won't be lost, Then have a jQuery dialog appear when they choose to view/checkout their cart. and it can list all products and then they simply fill in a simple form..
Is this the best way to go about it. Its a cheap website and I would like the simplest way to do this? All i guess I would need to sort is the product Id's..
Any ideas of better ways or any opinions at all!
Using Session depends on whether you think the users will pick the products in one go. Or will they leave the page and come back in an hour? The problem being that if they come back in an hour, the Session State may have been garbage collected to free up resources on the server, or the session might have expired.
To get around this, if all the products are on one page, you could store the chosen products in a hidden field, encrypted and all, that will stay there until the user closes the app.
You just need to serialize the list of product Ids, pass that serialized string to the view and put it in a hidden field.
Another option would be to store it in the users session. A benefit of this is if the user has cookies turned off and the site caters for cookieless session state then they will still be able to select products and checkout.
The thing to look out for is how much you could potentially end up storing in session. From the sounds of it this will not be an issue but if this could potentially use up an unacceptable amount of memory then you would probably need to consider a database approach anyway rather than cookies.
I'd say to go for the Session object. You can always configure the location of Sessions at runtime
I think some may dislike this storage method (it breaks testing isolation, if i'm not mistaken), but it's there for free :)
If you're using jquery, you could store the basket as a json array inside the $('body').data() element (or actually as i do, under a div called '#storage'). this works as a fantastic local storage mechanism, tho' would only be relevant to the current page that the user was on and would be cleared on moving to subsequent 'new pages' unless of course, your design was such that the shopping page was ALWAYS the same page and only refreshed by ajax methods. this way, you could continually append/modify the json structure on the 'worksurface' page.
i use this technique for a different application of the logic, but virtually for the same reason.
here's a snippet of the kind of thing i do:
/* example of data params key*/
var keyParams = "Data-Search-type-" + $('#searchtype').val();
/* add json to body with key*/
$('#storage').data(keyParams, jsonData);
/* get same data back later */
var jsonData = $('#storage').data(keyParams);
When i 'save' the data to the server, i then clear the data() element back to null. There is of course the other option of localstorage itself which can be used well, especially in disconnected environments (such as mobile apps).
another way to skin the many skinned cat!!
using asp.net mvc, I'm initializing a list in the server code, and allowing the end-user to add to the list on the form (using JQuery to add entries). I know how to obtain a list's selected items on a post back, but I don't need to do that here. I want the complete contents of the list accessible in the server code after a post back.
Is a posted list just not going to give me the full content? Should I use Ajax to send each item to the server as each items gets added to the list?
thanks
There are a couple of ways that I can think of doing this.
make an ajax call each time an item is added - as you suggested
when an item is added to the list, you also add a hidden field to the form that will be submitted. Then on post back (although that terminology is very Web Forms-y), in your action method, you'll have access to the contents of the list. If you name things correctly you should be able to model bind to a List.
The latter would be my preference, it depends on your particular situation though.
Some things to keep in mind:
Bandwidth from the user to the web server is very small compared to bandwidth from a database to the web server
The database most likely cached whatever query you just ran to populate that list
It sounds like you're asking for the entire list to be included with the postback data, and that means having the browser upload that data for the user.
With all that in mind, it should be obvious that you're better off rebuilding your base list from the database.