防止重复的pugixml :: xml_node [英] Prevent duplicate pugixml::xml_node

问题描述

我在写我的应用程序的一部分，存储设置在XML文件，但我不想'客户端'重复，我想这样：

I'm writing a part of my app that store settings in XML file, but I don't want to 'client' duplicate, I want this:

<jack>
  <client name="something">
    <port name="someport" />
    <port name="someport_2" />
  </client>
</jack>

但我得到：

<jack>
  <client name="something">
    <port name="someport" />
  </client>
  <client name="something">
    <port name="someport_2" />
  </client>
</jack>

认为只是检查节点是否已经存在，但这是问题，所以我有这个代码：

thought "just check if node already exists" but that's the problem, so I've this piece of code:

// xjack is the root node
pugi::xml_node xclient = xjack.child(sclient.c_str());
if (!xclient) {
    xclient = xjack.append_child("client");
}

但！xclient 总是评估为true，尝试也 if（xclient.empty（））但不工作也。

but !xclient always evaluate to true, tried also if (xclient.empty()) but not work also.

推荐答案

考虑评论zeuxcg我可以找出错误的原因。

thinking about the comments zeuxcg I could figure out what was wrong.

pugi :: xml_node xclient = xjack.child（sclient.c_str（））; 正在查找名称为something ，我要找的是一个标签，名称为client，属性name的值为something。

pugi::xml_node xclient = xjack.child(sclient.c_str()); is looking up for a child with name "something" that really doesn't exists, what I'm looking for is a tag with name "client" and attribute "name" with value of "something".

p>

So, the correct is:

pugi::xml_node xclient = xjack.find_child_by_attribute("client", "name", sclient.c_str());
if (!xclient) {
    xclient = xjack.append_child("client");
    xclient.append_attribute("name").set_value(sclient.c_str());
}

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