sap.m.Button 的 getBinding(“text") 未触发 attachChange 回调 [英] attachChange callback not fired for getBinding("text") of sap.m.Button

问题描述

onInit(): function{
    this._oSelectedTrainingsModel = new sap.ui.model.json.JSONModel([]);
    this.getView().setModel(this._oSelectedTrainingsModel, "selectedTrainings");
},

onAfterRendering: function() {
    this.getView().byId("ViewSelectionButton").getBinding("text").attachChange(this._onTextUpdated, this);
},

在 XML 视图中，我有这个绑定:

In the XML view I have this binding:

<Button id="ViewSelectionButton"
    class="magnificationPrep"
    icon="sap-icon://cart-full"
    tooltip="Share"
    text="{i18n>viewTrainingsButton} ({= %{selectedTrainings>/}.length })"
    press="handlePressViewSelection"
/>

在控制器中的某个点，一个对象被添加到_oSelectedTrainingsModel:

At some point in the controller, an object is added to the _oSelectedTrainingsModel:

this._oSelectedTrainingsModel.getProperty("/").push(oNewSelection);

此时，绑定的文本属性已更改，因此我期待调用回调函数 _onTextUpdated.

At this point, the bound text property is changed and thus I'm expecting a call to the callback function _onTextUpdated.

模型为空，这可能是问题的一部分?

The model is empty, this is probably part of the issue?

推荐答案

我相信由于您绑定模型和 Button 的 Text 属性的方式，不会触发更改事件.

I believe change event is not triggered because of the way you have bound your model and Text property of Button.

由于表达式绑定，发生了 ONE-WAY-BINDING，这意味着值将仅在 MODEL 中更改，不会反映在 UI 中.见下图:

Due to expression binding, ONE-WAY-BINDING has occured, meaning value will be changed in MODEL only and will not be reflected back in UI. See Image below:

为了解决这个问题，我手动触发了一个刷新事件，它会更新所有的绑定(强制)，因此触发了按钮文本的更改事件.

To Solve the problem, I manually triggered an refresh event, which will update all the binding(forcefully) and hence, change event of Button Text was triggered.

所以，代码:

    this.getView().getModel('newModel').getProperty("/").push({});
    this.getView().getModel('newModel').refresh(true);

其中 newModel 是我命名的模型.

where newModel is my named model.

然而，在调试时，我发现了两个问题::(

However, while debugging, I found two problems: :(

1. 为什么手动刷新后更改事件会触发两次?

1. Why is change event triggered twice after manual refresh ?

如果我这样做，不应该触发 onChange():

Shouldn't onChange() be triggered if I do:

this.byId('btn2').setText('Hey1!!') ?但事实并非如此.

希望能帮到你.

这篇关于sap.m.Button 的 getBinding(“text") 未触发 attachChange 回调的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！