如何按SAP UI5中可以为空的属性对列表进行分组？

Question

Im trying to group a list of items from an entity called Services. I want to group them by the attribute group1_ID. The problem is that some Services dont belong to a group, in which case the value for group1_ID is Null.

Ive run it with generated mock data where every Service had values !== Null for group1_ID. In this case it worked fine with my original attempt.

What I had originally written was this:

<List id="_phaseOverviewList" 
   items="{ 
   path:'/Services',   
   sorter: {path: 'group1_ID', group: true}}">

   <StandardListItem id="_IDEGen_standardlistitem0" title="{name}"/>
</List>

I've also considered trying to sort it in the Controller.js for that View. I guess that would go in the direction of the following, but I'm not sure and I'm not sure how I should implement that.

oList.getBinding(„items“).sort(new sap.ui.model.Sorter(„group_ID“, false, true));

I had hoped that the Services would be grouped based on the group1_ID attribute, and that Services with a Null value for group1_ID would be grouped together in the list. However, it just displays the list, unsorted/ungrouped.

Thanks in advance for your help.

Answer 1

From the specs what you do should already work, the null values should come at end. Instead of saying group: true you can provide a function that returns the group for each element. Something like this:

items="{ 
path:'/Services',   
sorter: {path: 'group1_ID', group: function(oContext){
let x = oContext.getProperty('group1_ID') || ''; //defaults to an empty string
return { key: x, title : x }}}}"

Have a look at https://gist.github.com/ikiw/bb2de7cd162bd88adf88 and for working examples. https://blogs.sap.com/2013/11/29/custom-sorter-and-grouper/