SAPUI5表达式绑定 [英] SAPUI5 Expression Binding

问题描述

是否可以将控件属性绑定到具有动态属性名称的模型，例如，存储在另一个模型字段中？我以为我们可以为此目的使用SAPUI5 表达式绑定，但它没有无法正常工作：跟踪窗口中的绑定被破坏，表达式似乎根本无法评估。

XML视图

 < TextArea value = {= $ {StackOverflow> / bindTextAreaTo}} /> 
  

控制器

< pre class = lang-js prettyprint-override> oModel = this.getView（）。getModel（ StackOverflow）;

/ *
*模型具有两个属性：问题和注释
*我希望根据某些条件
将TextArea的值绑定到其中之一* /

oModel.setProperty（ / question，）;
oModel.setProperty（ / comment，）;

oModel.setProperty（ / bindTextAreaTo，
bAsk？ StackOverflow> / question： StackOverflow> / comment）;


解决方案

否，目前无法实现。

但是，对于您要执行的操作有一个简单的解决方法（请参见下文）。
基本上，您创建一个视图模型并在该模型上设置一些布尔值。然后在表达式绑定中使用此标志来动态定义应使用哪种模型的属性...

XMLView

 < TextArea value = {= $ {view> / ask}？$ {StackOverflow> / question}：$ {StackOverflow> / comment}} /> 
  

控制器

  var oModel = this.getView（）。getModel（ StackOverflow）; 
 oModel.setProperty（ / question，）; 
 oModel.setProperty（ / comment，）; 
 // ... 
 
 var oViewModel = new sap.ui.model.json.JSONModel（）; 
 this.getView（）。setModel（oViewModel， view）; 
 // ... 
 
 oViewModel.setProperty（ / ask，bAsk）; 
  

Is it possible to bind control property to model with dynamic property name, stored, for instance, within another model field? I thought we can use SAPUI5 Expression Binding for this purpose, but it doesn't work: binding in trace window is broken and expression seems to be not evaluated at all.

XML View

<TextArea value="{= ${StackOverflow>/bindTextAreaTo} }" />

Controller

oModel = this.getView().getModel("StackOverflow");

/*
 * The model have two properties: question and comment
 * I want value of TextArea to be bound to one of them based on some condition
 */

oModel.setProperty("/question", "");
oModel.setProperty("/comment", "");

oModel.setProperty("/bindTextAreaTo", 
    bAsk ? "StackOverflow>/question" : "StackOverflow>/comment" );

解决方案

No, that's currently not possible.

However, there is a simple workaround for what you want to do (see below). Basically, you create a view model and set some boolean value on the model. This flag is then used in your expression binding to define "dynamically" what property of what model shall be used...

XMLView

<TextArea value="{= ${view>/ask} ? ${StackOverflow>/question} : ${StackOverflow>/comment} }" />

Controller

var oModel = this.getView().getModel("StackOverflow");
oModel.setProperty("/question", "");
oModel.setProperty("/comment", "");
//...

var oViewModel = new sap.ui.model.json.JSONModel();
this.getView().setModel(oViewModel, "view);
//...

oViewModel.setProperty("/ask", bAsk);

这篇关于SAPUI5表达式绑定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！