oData v2 model has the feature to cache the used data and read data. I want to disable the cache feature. I don't want to keep the data in my model. Any suggestions?
You cannot disable cache. But you also don't really need to.
If you're afraid that the cached data is old, just use the refresh method to get the model to retrieve new data from the server. When you execute the refresh method, each binding reloads its data from the server. For list or element bindings, a new request to the backend is triggered.
Related
I have a table of data that I want to update dynamically.
When the user goes to the page, I want to initialize the table with data from my rails backend. Easy with the model hook and ember data.
I then want to keep this information refreshed using the connected websocket stream.
How should I manage this. Should I be updating the model with the websocket updates (without committing the data to the backend)? The table data is an object array in the component, should I just initialize this from the model setupController function then keep the array updated directly?
Is there an easy way to map the websocket data JSON into the model or table array?
Yes you should be able to do this with Ember Data. Caveat: I have not tried this.
Somewhere you are opening your websocket stream and adding an "onmessage" handler. In that handler, you will receive the payload from the server, where you can use store.pushPayload() to update the record in the store. If the record (identified by the id field) is already in the store, it will be replaced. Otherwise it will be added as a new record. If you are displaying the record in the current template, you should just see the values change when the new record is pushed.
This Ember guide page describes this scenario, where you are streaming data from the server and you want to see instant updates to the user interface.
Additional reading: the API for pushPayload
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.
One of my application is using Parse.com as its backend service. There is one table called Product which is queried through cachePolicy as kPFCachePolicyCacheElseNetwork. The problem is the client side always got the cached data even after I modified some of the fields. The reason I don't always get data through network is that I'm trying to save data traffic as much as possible.
My question is if there is a way to expire the cache in server side so that I'll get new data in client side as soon as I modify the data? Thanks (My only solution by far is to delete the client app and reinstall it.This obviously is not an ideal solution.)
You need to decide some time limit on the cache validity, generally on the client, and either call clearCachedResult on the query instance or clearAllCachedResults on PFQuery when the limit is exceeded.
You could create a cloud function which returns a minimal amount of data and informs the app about changes so it can decide how / when / which caches to remove. For example, you pass a list of class names and last requested dates and the cloud function returns the names of classes which have new data since those dates.
In an app I'm building, I'm using Core Data to cache remote content from an API for offline viewing. This all works pretty well except for one big issue: if a record on the server is deleted there's no way for me to detect that and delete its cached counterpart.
The only thing I can think of is somehow marking all the current data as 'invalid' when I pull data from the API and only mark the records returned by the API as valid again, but it seems like this is a clunky solution to the problem. Additionally, as data from the API I'm using is paginated it doesn't scale well for lots of records.
So what I want to know is: is there a better way to invalidate local cache data in response to it being deleted server-side?
I would suggest, although not the easiest route, is to have the server side cache items that are deleted and expose an endpoint you can call to get the deleted items. In a perfect world right.
What you can do is in a background thread, download all the data from the server and compare it to what you have locally. So instead of just invalidating all of it and re-parsing it back in (which can take time for large data sets), just run through and compare id's of objects on the server to your objects in CoreData. If it's there great, if not delete it from you local db. Hope this helps.
I am porting an application from wpf to asp.net mvc.
In the wpf I have a view in which the user selects from a combobox the name of a client and then in some textboxes, next to the combobox, some specific information about the client will show up (email, address, etc). In wpf I fill all this information in an observablecollection that resides in memory and when the client changes, I retrieve the other ones from the collection so it won't fo through the database.
Is there any way in asp.net mvc I can do this ? Or every time the client changes i will fetch from the database the extra information ? (will be slow)
This controls is just to select the client (and the extra information to help the user) so it should be fast.
How would you do it ?
If you don't want to make a call back to the server for every selection, then you should look at a solution whereby you pre-fetch all the data that you need and hold it in a javascript object. Then you could write a javascript method that would fire on the selection DOM event.
Sounds like what you are looking for is Session. You can pull the list from the database once, store it in session, and then reference session as needed for each client's data. This recommendation is based on presumption that the list is not being modified elsewhere, and therefore, invalidating the version of the list you have stored in Session.
Using Session in ASP.NET - http://msdn.microsoft.com/en-us/library/ms178581.aspx