XPath 在双重条件下取元素 [英] XPath take element on double condition

问题描述

我有一个来自 OPC-UA 的信息模型，用 xml (https://github.com/OPCFoundation/UA-Nodeset/blob/v1.04/Robotics/Opc.Ua.Robotics.NodeSet2.xml).从这个模型我想:查看 UAObject 中的引用并仅在引用具有时才获取 DisplayName1)我要找的nodeid2) 有一个字段 IsRecursive="false"

I have an InformationModel from OPC-UA, written in xml (https://github.com/OPCFoundation/UA-Nodeset/blob/v1.04/Robotics/Opc.Ua.Robotics.NodeSet2.xml). From this model I want to: Look at the reference inside an UAObject and get the DisplayName only if the reference has 1)The nodeid I am looking for 2)Has a field IsRecursive="false"

我尝试使用此代码来获取所有对象的引用，该引用指向我指定的 nodeid 并且它可以工作.这是它的代码:

I tried this code for getting all object with a reference which point to my specified nodeid and it works. Here it is the code for it:

var ObjectsName2 = select(
    "//ns1:References/ns1:Reference[.=" +
      formatted_id + "]/ancestor::ns1:UAObject/ns1:DisplayName/text()",
    nodes,
    false
  );

现在我想采用具有特定 nodeid 且字段 IsForward 设置为false"的那个.所以我有一个双重条件需要用 AND 来验证.这是我正在使用的代码:

Now I want to take the one that has the specific nodeid and has field IsForward setted to "false". So I have a double condition that needs to be verified with an AND. Here it is the code I am using:

var formatted_id = '"' + ParentNodeId + '"';
  var negate = "false";
  var ObjectsName = select(
    "//ns1:References/ns1:Reference[.=" +
      formatted_id + 
      "//@ns1:IsForward="+negate+"]/ancestor::ns1:UAObject/ns1:DisplayName/text()",
    nodes,
    false
  );

错误的结果是一个空数组.为了让这里更容易理解，这是一个显示我想要的示例.

The wrong result is an empty array. To make a bit easier to understand here it is an example that shows what I want.

假设您有这个 xml 条目，而我要查找的节点是 ns=1;i=15008:

Imagine you have this xml entry and the node that I am looking for is ns=1;i=15008:

<UAObject NodeId="ns=1;i=15024" BrowseName="2:ParameterSet" ParentNodeId="ns=1;i=15008">
   <DisplayName>ParameterSet</DisplayName>
   <Description>Flat list of Parameters</Description>
   <References>
     <Reference ReferenceType="HasComponent">ns=1;i=15061</Reference>
     <Reference ReferenceType="HasTypeDefinition">i=58</Reference>
     <Reference ReferenceType="HasModellingRule">i=78</Reference>
     <Reference ReferenceType="HasComponent" IsForward="false">ns=1;i=15008</Reference>
   </References>
 </UAObject>

如您所见，有一个名为HasComponent"的引用.它指向我的节点 (ns=1;i=15008) 并且 IsForward=false".

As you can see there is a Reference called "HasComponent" which points to my node (ns=1;i=15008) and IsForward="false".

预期的输出应该是输出数组中UAObject的显示名称-->ParameterSet有人可以帮我吗?

The expected output should be the display name of the UAObject in the output array -->ParameterSet Can someone help me?

推荐答案

单纯基于xpath，这个表达式:

Simply based on xpath alone, this expression:

//Reference[@ReferenceType="HasComponent"][@IsForward="false"]

应在示例 xml 中选择 ns=1;i=15008.

should select ns=1;i=15008 in your sample xml.

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