问题
In section 10 of the OpenUI5 Developer Guide tutorial on routing (see here), it talks about lazy loading. However the tutorial does not show how to lazy-load data.
Scenario: I have an OpenUI5 app that gives a list of employees and on a detail page shows the main employee details and gives access to further info, projects, hobbies, and notes from the selected employee's resume.
Because in 99.99% of the use cases a user will not wish to look at hobbies, I will prefer not to load hobbie data with the main model for the app. I make this choice based on performance concerns. Instead I will detect the user has requested to see hobbies and load the hobbies data for the current user into the model.
How would I do that ?
Edit: I managed to discover the onTabSelect() plumbing [tip to other confused folks, the OpenUI5 tutorials tend to leave stuff out to keep on topic - it is useful to look at the code of their working versions if you get lost]. After this the routing in the tutorial makes a lot more sense.
My question remains relevant but changes slightly to 'User clicks a tab and I am about to load further JSON data into the model. Should I do this in onInit() of the target controller or before navTo() is invoked to load the controller?' I can see an issue because of the async nature of the JSON fetch meaning if I use onInit() I could end up displaying the page controls before the data arrives.
What is the best practice please ? My money is on pre navTo() though that is an ugly pattern as I would have to repeat the JSON fetch elsewhere if I have another route to the lazy-loading view.
回答1:
To stick with the example. You can attach your HobbiesController in its onInit method to the display event of the target you are displaying:
var router = this.getOwnerComponent().getRouter();
var target = router.getTarget("resumeTabHobbies");
target.attachDisplay(this.onDisplay, this);
Then you define an onDisplay method which will be now called if you select the corresponding tab and populate your model there.
来源：https://stackoverflow.com/questions/40258071/lazy-loading-data-after-initial-load