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I am trying to write a program that reads an XML file into a previously defined Rust struct.
Something like this:
<?xml version="1.0" encoding="UTF-8"?>
<note name="title">
<body name="main_body">
<layer content_type="something" count="99">
<data id="13">
Datacontent
</data>
</layer>
</body>
</note>
Into this:
struct Note {
name: String,
Body: Body
}
struct Body {
name: String,
layers: Vec<Layer>,
}
struct Layer {
content_type: String,
count: u8,
data: Vec<Data>,
}
struct Data {
id: u8,
// Datacontent?
}
I looked at xml-rs because it currently appears to be the most popular XML library. Being new to Rust, I have a hard time figuring out how to perform this task.
306
xml file is read with the ioutil. ReadFile() function and a byte slice is returned, which is then decoded into a struct instance with the xml. Unmarshal() function. The struct instance member values are used to print the decoded data.
Read XML File into MATLAB® Structure ArrayCreate a parsing function to read an XML file into a MATLAB® structure, and then read a sample XML file into the MATLAB workspace. To create the function parseXML , copy and paste this code into an m-file parseXML. m .
Encoding is the process of converting unicode characters into their equivalent binary representation. When the XML processor reads an XML document, it encodes the document depending on the type of encoding. Hence, we need to specify the type of encoding in the XML declaration.
Rust has great support for automatically generating (de)serialization code. There's the legacy rustc-serialize which requires very little setup. Then there's the serde crate which is a completely new (de)serialization framework that allows many formats and detailed custom configurations, but requires a little more initial setup.
I'm going to describe how to use serde + serde_xml_rs to deserialize the XML to the Rust-structs.
Cargo.toml
We could either implement the deserialization code manually, or we can generate it automatically by using the serde_derive crate.
[dependencies]
serde_derive = "1.0"
serde = "1.0"
serde-xml-rs = "0.3.1"
Serde needs to know about your structs. To aid it and not generate code for every single struct in your project, you need to annotate the structs you want. The Debug derivation is so we can easily print the structs with println! to inspect whether everything worked. The Deserialize bound is what notifies serde to generate code. If you want to treat the contents of an xml tag as text, you need to "rename" the field that should contain the text to $value. The naming of $value was done very arbitrarily in the creation of the serde_xml_rs crate, but can never collide with an actual field, because field names can't contain $ signs.
#[macro_use]
extern crate serde_derive;
extern crate serde;
extern crate serde_xml_rs;
#[derive(Deserialize, Debug)]
struct Note {
name: String,
body: Body,
}
#[derive(Deserialize, Debug)]
struct Body {
name: String,
#[serde(rename="layer")]
layers: Vec<Layer>,
}
#[derive(Deserialize, Debug)]
struct Layer {
content_type: String,
count: u8,
data: Vec<Data>,
}
#[derive(Deserialize, Debug)]
struct Data {
id: u8,
#[serde(rename="$value")]
content: String,
}
Now comes the easy part. You call serde_xml::from_str on your string and you get either an error or a value of type Node:
fn main() {
let note: Note = serde_xml_rs::deserialize(r##"
<?xml version="1.0" encoding="UTF-8"?>
<note name="title">
<body name="main_body">
<layer content_type="something" count="99">
<data id="13">
Datacontent
</data>
</layer>
</body>
</note>
"##.as_bytes()).unwrap();
println!("{:#?}", note);
}
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