xmlserde

xmlserde is a tool for serializing or deserializing xml struct. It is designed for LogiSheets, which is a spreadsheets application working on the browser.

You can check the detail of usage in the workbook directory or here.

How to use xmlserde

xmlserde offers a range of macros that should suffice for most use cases. To utilize them, you need to include the following crates in your Cargo.toml file:

xmlserde = 0.10
xmlserde_derives = 0.10

Deserialize

Start from deserializing would be easier to get closer to xmlserde.

Given the xml struct as below,

<person age ="16">Tom</person>

We can deserialize with these code:

use xmlserde_derives: XmlDerserialize
#[derive(XmlDeserialize)]
#[xmlserde(root = b"person")]
pub struct Person {
    #[xmlserde(name=b"age", ty="attr")]
    pub age: u8,
    #[xmlserde(ty ="text")]
    pub name: String,
}

fn deserialize_person() {
    use xmlserde::xml_deserialize_from_str;

    let s = r#"<person age ="16">Tom</person>"#;
    let p = xml_deserialize_from_str(s).unwrap();
    assert_eq!(p.age, 16);
    assert_eq!(p.name, "Tom");
}

You are supposed to declare that where the deserializer is to look for the values.

The commonly available types are attr, text and child. In the above example, we instruct program to navigate into the tag named person (using xml_deserialize_from_str), and to search for an attribute with the key age. Additionally it specifies that the content of the text element represents the value of the field name.

You can specify the entry element for serialization/deserialization with xmlserde by using the annotation like #[xmlserde(root = b"person")], thereby telling the program that the person element is the root for serde operations.

Below is an example illustrating how to deserialize a nested XML element:

#[derive(XmlDeserialize)]
#[xmlserde(root = b"person")]
pub struct Person {
    #[xmlserde(name=b"age", ty="attr")]
    pub age: u8,
    #[xmlserde(name = b"lefty", ty ="attr", default = "default_lefty")]
    pub lefty: bool,
    #[xmlserde(name = b"name", ty ="child")]
    pub name: Name,
}

#[derive(XmlDeserialize)]
pub struct Name {
    #[xmlserde(name = b"zh", ty ="attr")]
    pub zh: String,
    #[xmlserde(name = b"en", ty ="attr")]
    pub en: String,
}

fn deserialize_person() {
    use xmlserde::xml_deserialize_from_str;

    let s = r#"<person age ="16"><name zh="汤姆", en="Tom"/></person>"#;
    let p = xml_deserialize_from_str(s).unwrap();
    assert_eq!(p.age, 16);
    assert_eq!(p.name.en, "Tom");
    assert_eq!(p.lefty, false);
}

fn default_lefty() -> bool { false }

In the given example, we specify that the value of the name field is to be extracted from a child element tagged as <name>. Consequently, the program will navigate into the <name> element and proceed with recursive deserialization.

Additionally, we specify that if the deserializer does not find a value for lefty, the default value for lefty should be set to false.

Vec

We support deserialize the fields whose types are std::Vec<T: XmlDeserialize>.

#[derive(XmlDeserialize)]
pub struct Pet {
    // Fields
}

#[derive(XmlDeserialize)]
#[xmlserde(root = b"person")]
pub struct Person {
    #[xmlserde(name = b"petCount", ty = "attr")]
    pub pet_count: u8,
    #[xmlserde(name = b"pet", ty = "child")]
    pub pets: Vec<Pet>
}

When the deserializer find the pet element, and it will know that this is an element of pets. You can even assign the capacity of the Vec with following:

#[xmlserde(name = b"pet", ty="child", vec_size=3)]

If the capacity is from an attr, you can:

#[xmlserde(name = b"pet", ty="child", vec_size="pet_count")]

Enum

We provide 2 patterns for deserializing Enum.

#[derive(XmlSerialize, XmlDeserialize)]
enum TestEnum {
    #[xmlserde(name = b"testA")]
    TestA(TestA),
    #[xmlserde(name = b"testB")]
    TestB(TestB),
}

#[derive(XmlSerialize, XmlDeserialize)]
#[xmlserde(root = b"personA")]
pub struct PersonA {
    #[xmlserde(name = b"e", ty = "child")]
    pub e: TestEnum
    // Other fields
}

#[derive(XmlSerialize, XmlDeserialize)]
#[xmlserde(root = b"personB")]
pub struct PersonB {
    #[xmlserde(ty = "untag")]
    pub dummy: TestEnum
    // Other fields
}

PersonA can be used to deserialize the xml struct like below:

<personA><e><testA/></e></personA>

or

<personA><e><testB/></e></personA>

And PersonB can be used to deserialize the xml which looks like:

<personB><testA/></personB>

or

<personB><testB/></personB>

You can use untag to Option<T> or Vec<T> where T is an Enum.

It means that the example below is legal:

#[derive(XmlSerialize, XmlDeserialize)]
#[xmlserde(root = b"personB")]
pub struct PersonB {
    #[xmlserde(ty = "untag")]
    pub dummy1: Enum1,
    #[xmlserde(ty = "untag")]
    pub dummy2: Option<Enum2>,
    #[xmlserde(ty = "untag")]
    pub dummy3: Vec<Enum3>,
    // Other fields
}

Unparsed

In situations where certain XML elements are not immediately relevant, but you wish to retain them for future serialization, we offer the Unparsed struct for this purpose.

use xmlserde::Unparsed;

#[derive(XmlDeserialize)]
pub struct Person {
    #[xmlserde(name = b"educationHistory", ty = "child")]
    pub education_history: Unparsed,
}

Serialize

Serialization is largely similar to deserialization. However, there are several key features that require consideration.

• default values will be skipped serializing. If it is a struct, it should be implemented Eq trait.

• If a struct has no child or text, the result of serializing will look like this:

  <tag attr1="value1"/>

Custom xmlserde

xmlserde offers the trait XmlSerialize and XmlDeserialize, allowing you to dictate a struct's serialization and deserialization behavior by implementing these traits. At present, only built-in types are permitted for use as attributes. To enable custom types for use in attributes, you can implement the XmlValue trait on those types.

Enum for string type

xmlserde also provides a macro called xml_serde_enum to serde enum for string type.

xml_serde_enum defines an enum and specifies the behavior of serialization and deserialization.

use xmlserde::xml_serde_enum;

xml_serde_enum!{
    #[derive(Debug)]
    Gender {
        Male => "male",
        Female => "female",
    }
}