On Page Load event in vaadin - vaadin

I have page with table that populates data based on complex query(takes lot of time even though I use pagination). I use BeanItemcontainer to load data in to the table. Now coming to the problem, I wish to load the data in to the table in a async way(after the complete page gets loaded on the user screen. I wan to populate the data). Is there some thing like onPageLoad event or onPageRenderEvent or equivalent that I can use to achieve this?
Details -
Version - Vaadin -7.0
Component - Table
Data Container - BeanItemContainer.

There's a number of ways to solve this, but you have to decide how you want to approach the problem. Here's two that I know of:
1) Request from the client.
2) Push from the server. (technically still a request from the client)
1 -- A) Request from a Javascript function programmed on the client-side. Attach the component to a layout by using a Javascript Extension or a Javascript component and make requests by calling a server-side API function. You can then update the table within that request and not worry about syncing issues.
1 -- B) Make your own GWT / Vaadin widget (same thing, basically) to do 1A.
2 -- A) Request from a Vaadin component programmed on the "server-side." Make a visible (or invisible) progress indicator that polls the server. Populate the table in a background thread and Vaadin will send the data you've currently gathered. The progress indicator can do this many times and the table will only send the difference to the client-side code (called the delta). Be careful updating client-facing components from background threads; you need to sync on changes to the component to avoid concurrent modification errors.
2 -- B) Add a refresher to the application and follow 2A above without needing a progress indicator.
Either solution involves you explicitly updating the table, either in a background thread (2A,B) or in the server method called from the client (1A,B). And both are technically client-request based. The Vaadin team are working on adding true 'push.'

The Vaadin way to solve this problem is to use a lazy loading Container. There are several lazy loading containers available for Vaadin: SQLContainer in core, LazyQueryContainer and JPAContainer.

Related

Umbraco automatic update

I need some help with umbraco.
Let's say that I have an umbraco grid with a custom editor, just like the one in this tutorial: https://our.umbraco.com/documentation/Getting-Started/Backoffice/Property-Editors/Built-in-Property-Editors/Grid-Layout/build-your-own-editor
Ok, so I wrote this editor to build a gallery of items with image/title, I get the item list from an api call made by an angular service and this works fine when I publish the page by hand. What I want is to automatically update this gallery with new items where available, so my idea was to make a timed ajax call, let's say every hour, to update the items. But sadly this doesn't work, I suppose that the call is made but the list isn't updated.
Any suggestion? Thanks
You need to handle this differently. Right now it sounds like what you have is an implementation that works when you are browsing to this node in the backoffice using your browser and the browser makes the API calls through Angular. This all happens in your UI and when you manually hit save/publish - the data in the UI gets saved. Keep in mind that this is basically your browser doing the "work" - and this (and all other Angular code) will of course only ever run while your browser is open, in the backoffice, viewing this node.
What you want to do is to have this run automatically (and preferably in some sort of background task) to ensure that you do not really have to open up the backoffice for this to actually be automatically updated over time.
You need to create some sort of background job running on the server-side instead. This would have to be done in C# and I would recommend looking into Hangfire or Quartz frameworks to handle all the scheduling/making sure the job runs.
This job/task should do the external API calls in C# and transform the result into the same format as the format you are saving when you save data from the manual update. Then fetch the content nodes you need to update using the ContentService API and update the specific property values on those nodes. When this is done you need to make sure the changes are saved and the node is then republished with its updated data. All of this is done through the ContentService.

How to refresh all (OData) bindings of a given SAPUI5 page?

I have a bigger SAPUI5 application with multiple pages.
If user navigates through all these pages, they will reside in memory of course.
Now I have the problem that some of these pages have a complex context with several bindings to an ODataModel. That leads to the problem that a .refresh() call on the underlying ODataModel take some time.
Because: all known bindings will be reloaded (also from pages not currently shown)
Now I am searching for a better solution to refresh the ODataModel.
The refresh must be done because sometimes a client action triggers the server to updates multiple data (in different models!).
Further information (Edit)
I am using multiple ODataModels in my application and they are created in the Component.js (as suggested in the Best practice chapter of the SDK documentation).
Navigating through the pages will increase the cached data in the ODataModel.
Calling a .refresh() seems to reload all cached data (still used or not).
According to the first reply it is possible to refresh one binding but how to refresh all bindings of a given view/page with multiple models?
Would it be the right way to set multiple instances of the ODataModel for each view? And just call the .refresh() method there? But also on this scenario the locally cached data will increase over time?
Any ideas welcome :)
You can access the binding of a specific UI control and call refresh there. This should just process this specific binding.
My first hint would be to use the v2 OData Model (sap.ui.model.odata.v2.ODataModel), as it uses the Batch Mode by default.
Moreover, when it performs updates, it refreshes all bindings of entities that have been updated automatically so you should not need to refresh the whole model at all.
For me it worked to just re-bind that binding on a specific element in the view as I did earlier to create it at all.
We had an update-problem after another update call had side effects on the information in question, but a refresh on the binding of the elemnt itself did not solve that. I guess there were no local changes to that path in the model, so there was nothing to refresh. But on server-side there where updates the model/Cache didn't know about. Rebinding made my day, and also only the one necessary call to the servcie was made.

"State" management for asp.net mvc multi partial view + ajax app

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.

Firefox content script memory consumption

I am developing one extension for Firefox using addon-sdk. That extension opens one tab and load one web page which is updated each N minutes. This web page is processed using one content script. The problem is that memory grows each time the content script gets executed. Do you know why? Is there any way to call any garbage collector in order to maintain memory consuption stable?
EDIT:
The web page contains bank account details and the Content Scripts look for new movements on in. It is a framed page and one of its frames (which contains movements list) is reloaded to see if any change occured. I use jquery to proccess the list.
When new movements appear, those are sent to the extension using port and the extension saves them in a remote web server using Response.
Trying check this instructions by mozilla:
https://developer.mozilla.org/en/XUL_School/JavaScript_Object_Management
https://developer.mozilla.org/en/Zombie_Compartments#Proactive_checking_of_add-ons
Depends on what are you using on your add-on... If you're using some oberserver for example, you need to unregister this observer so it won't leak... Can you give more descriptions about your addon? The code or exactly what it does...
Maybe you're not declaring variabled and you're using globals all the time, try also unset the variable after use it.
Are you using jquery?

Trouble with react final form FieldArray, listeners and displaying data from api call outside of form

I want to trigger an API call to fetch some supplemental data and display it alongside my react final form. What's the best way to do this?
I've started by using OnChange from react-final-form-listeners to listen for a field change and make an API call, but I don't really know how to store this data somewhere and display it within the react-final-form framework. Using a functional component and a State hook, it would be relatively trivial, because I would just set the state of a variable and then display it somewhere in the same component. Is this a sign that I should be storing these kinds of things in redux? Can I use hooks instead?
I forked one of the examples and added what I am trying to do:
https://codesandbox.io/embed/react-final-form-field-arrays-k9pqm
You're talking a little too abstractly about your goal here, but sure, you could keep the loaded data in state with a useState() hook. If I were you, I'd want to debounce it, and keep track of whether or not the Promise from your API call was the Promise from the last call or not.

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