Getting all inner element along with it's attributes

[surajchhetry]

Hi there,
I need help to get all the nested element along with it's attribute. I want to get all the nested elements of <element1> along with it's attributes from given very large xml file .

<root-1>
<element1>
  <inner-1 id="1234">
       <inner-inner-1 a="abc" b="xyz"></<inner-inner>
  </inner-1>
  <inner-1 id="2345">
       <inner-inner-1 a="abc22" b="xyz44"></<inner-inner>
  </inner-1>

</element1>
</root-1>

<root-1>
<element1>
  <inner-1 id="23x3">
       <inner-inner-1 a="abc1" b="xyz1"></<inner-inner>
  </inner-1>
  <inner-1 id="234215">
       <inner-inner-1 a="abc223" b="xyz474"></<inner-inner>
  </inner-1>

</element1>
</root-1>
  

[Mingun]

It's quite hard to answer to your very broad question. What API you want to use? Serde or just raw XML events?

If I correctly understand your example, you have multi-root document (probable streamed from its source) and you want to deserialize it.

This is the start point that you can use to work with serde deserialization:

// <inner-inner-1 a="abc" b="xyz"></<inner-inner>
#[derive(Deserialize)]
struct InnerInner {
  #[serde(rename = "@a")]
  a: String,
  #[serde(rename = "@b")]
  b: String,
}

// <inner-1 id="1234">
#[derive(Deserialize)]
#[serde(rename_all = "snake_case")]
struct Inner {
  #[serde(rename = "@id")]
  id: String,

  // I'm not sure what the element name is,
  // the open tag is `<inner-inner-1>` and close is `</inner-inner>`
  inner_inner: InnerInner,
}

// <element1>
#[derive(Deserialize)]
struct Element {
  #[serde(default)]
  inner: Vec<Inner>,
}

// <root1>
#[derive(Deserialize)]
struct Root {
  element1: Element,
}

Those types should allow you to deserialize one <root-1> element. To deserialzie a stream of values, use the technique described in official serde site.

If you find that quick-xml missed some features preventing you to implement deserialization, feel free to open an issue or PR that adds them.

[surajchhetry]

Hi @Mingun ,
thank you for your answer. Between Serde and XML event which one will be better for large file processing ?

[Mingun]

Serde is definitely a slower than XML events, about 3x times according to results of compare project with sample_rss.xml.

You also can try to use https://lib.rs/crates/xmlserde which uses quick-xml but provides serde-like derives specially for XML. I plan to add it to comparison project, but was not able to do that due to that fact it is depends on the quick-xml and we need find a way to substitute its dependency with local quick-xml copy.