如何从 XML 视图中的扩展集合绑定 OData $count [英] How to Bind OData $count from expanded collection in an XML view

问题描述

这可能是一个基本问题，但我无法在 XML 视图中绑定 OData 计数.

May be this is a basic question, but I have trouble binding the OData count in XML view.

在以下示例中，我想绑定来自 OData 模型的产品数量.

In the following example, I want to bind the count of products from the OData model.

<List items="{/Categories}"} >  
  <ObjectListItem
    title="{CategoryName}"
    number="{path : 'Products/$count'}"
    numberUnit="Products"/>
</List>

每个类别都需要显示相应类别中的产品数量，如

Each category needs to display count of products in the respective category as in

/Categories(1)/Products/$count
/Categories(2)/Products/$count

推荐答案

我认为目前不可能- $count 是一个 OData 查询选项，ODataListBinding 中的等价物是长度，例如 Products.length 我想不出绑定到它的方法

I dont think its currently possible - $count is an OData query option, the equivalent in ODataListBinding is length, eg Products.length I cant think of a way to bind to it

您可以使用格式化程序以多种方式实现计数

you can achieve the count in a couple of ways using a formatter

选项 1 - 最简单的方法，创建一个读取产品总数的列表绑定，它执行同步调用并仅返回 $count

option 1 - the simplest, create a list binding which reads the total number of products, it does a synchronous call and returns only the $count

function productCount(oValue) {
    //return the number of products linked to Category // sync call only to get $count
    if (oValue) {
        var sPath = this.getBindingContext().getPath() + '/Products';
        var oBindings = this.getModel().bindList(sPath);
        return oBindings.getLength();
    }
};

<List items="{/Categories}"} >  
 <ObjectListItem 
    title="{CategoryName}"
    number="{path : 'CategoryName',formatter:'productCount'}"
    numberUnit="Products" 
 </ObjectListItem>
</List>

选项 2 - 使用扩展并返回非常小的数据集，在这种情况下只有 CategoryName 和 ProductID，这里的警告是您是否必须通过表分页来获取完整列表

option 2 - use an expand and return a very small set of data, in this case only CategoryName and ProductID, the caveat here is whether you have to by pass table paging to get full list

function productCount(oValue) {
    //read the number of products returned
    if (oValue) {
        return oValue.length;
    }
};

<List items="{/Categories,parameters:{expand:'Products', select:'CategoryName,Products/ProductID'}}">  
 <ObjectListItem 
    title="{CategoryName}"
    number="{path : 'Products',formatter:'productCount'}"
    numberUnit="Products" 
 </ObjectListItem>
</List>

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