Perform Action after the Binding Is Complete

问题:

I wrote this part to bind OData information with a select controller:

var countrItems = new sap.ui.core.ListItem();
countrItems.bindProperty("key", "Land1");
countrItems.bindProperty("text", "Landx");
var CountrSelect = this.byId("CountrySelect");
CountrSelect.setModel(oModelTriptab);
CountrSelect.bindItems("/Countries", countrItems);

I would like to perform an action after the binding is complete (I want to select some default value that can change dynamically).

回答1:

Use the model's requestCompleted event handler to perform any actions that should happen right after your model data is updated.

The binding itself should be rather static (i.e. it will not change) so you'r only interested in when the data is changed

---

edit here's an example implemantation:

var that = this;
oModelTriptab.attachRequestCompleted(function(oEvent){
    var oSelect = that.byId("CountrySelect");
    oSelect.setSelectedKey("whatever");
});

See https://openui5.hana.ondemand.com/docs/api/symbols/sap.ui.model.Model.html#attachRequestCompleted for more info

回答2:

Attach handlers to events provided by Binding:

<Select items="{
  path: '/Countries',
  events: {
    dataRequested: '.onCountriesRequested',
    dataReceived: '.onCountriesReceived',
    change: '.onCountriesChange'
  }
}">

Those events can be applied, not only to ListBindings, but to all bindings. Note: PropertyBindings do not trigger any requests, so no dataRequested or dataReceived for them.

I would like to perform an action after the binding is complete.

In that case, you'd attach a handler either to change or dataReceived event to be notified about the "complete" binding.

Compared to attaching a handler to requestCompleted, the above approach is more descriptive and, most importantly, binding-specific.

---

List, m.Table, m.Tree, ...

Alternatively, UI5 offers the event updateFinished for Controls derived from sap.m.ListBase. It's similar to the change event, but provides more information such as an additional "Growing" reason, actual, and total count of the entries.

<List
  updateFinished=".onCountriesUpdateFinished"
  items="..."
>

onCountriesUpdateFinished: function(event) {
  const reasonForUpdate = event.getParameter("reason"); // "Refresh", "Growing", "Filter", "Sort", "Context", ...
  const currentlyLoadedNumberOfCountries = event.getParameter("actual");
  const totalNumberOfCountries = event.getParamter("total") // Value of $count
  // ...
}