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Add expand_empty_elements fn to Serializer (#620)
* Add expand_empty_elements fn to Serializer Setting this to true will serialize empty elements to <element></element> instead of <element/>. * Move the expand empty elements logic into write_empty * Add doctest example for expand_empty_elements * Add entry to CHANGELOG.md * Link to issue instead of PR in changelog
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‎Changelog.md‎

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@@ -15,6 +15,7 @@
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- [#609]: Added `Writer::write_serializable` to provide the capability to serialize
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arbitrary types using serde when using the lower-level `Writer` API.
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- [#615]: Added ability to set entity resolver when deserialize using borrowing reader.
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- [#617]: Added ability to enforce the expansion of empty elements.
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### Bug Fixes
2021

@@ -26,6 +27,7 @@
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[#604]: https://github.com/tafia/quick-xml/issue/604
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[#609]: https://github.com/tafia/quick-xml/pull/609
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[#615]: https://github.com/tafia/quick-xml/pull/615
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[#617]: https://github.com/tafia/quick-xml/pull/617
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## 0.29.0 -- 2023-06-13

‎src/se/content.rs‎

Lines changed: 19 additions & 3 deletions
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@@ -56,6 +56,9 @@ pub struct ContentSerializer<'w, 'i, W: Write> {
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/// If `true`, then current indent will be written before writing the content,
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/// but only if content is not empty.
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pub write_indent: bool,
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// If `true`, then empty elements will be serialized as `<element></element>`
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// instead of `<element/>`.
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pub expand_empty_elements: bool,
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//TODO: add settings to disallow consequent serialization of primitives
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}
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@@ -85,16 +88,25 @@ impl<'w, 'i, W: Write> ContentSerializer<'w, 'i, W> {
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level: self.level,
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indent: self.indent.borrow(),
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write_indent: self.write_indent,
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expand_empty_elements: false,
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}
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}
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/// Writes `name` as self-closed tag
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#[inline]
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pub(super) fn write_empty(mut self, name: XmlName) -> Result<(), DeError> {
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self.write_indent()?;
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self.writer.write_char('<')?;
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self.writer.write_str(name.0)?;
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self.writer.write_str("/>")?;
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if self.expand_empty_elements {
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self.writer.write_char('<')?;
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self.writer.write_str(name.0)?;
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self.writer.write_str("></")?;
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self.writer.write_str(name.0)?;
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self.writer.write_char('>')?;
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} else {
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self.writer.write_str("<")?;
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self.writer.write_str(name.0)?;
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self.writer.write_str("/>")?;
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}
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Ok(())
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}
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@@ -483,6 +495,7 @@ pub(super) mod tests {
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level: QuoteLevel::Full,
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indent: Indent::None,
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write_indent: false,
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expand_empty_elements: false,
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};
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$data.serialize(ser).unwrap();
@@ -503,6 +516,7 @@ pub(super) mod tests {
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level: QuoteLevel::Full,
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indent: Indent::None,
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write_indent: false,
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expand_empty_elements: false,
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};
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match $data.serialize(ser).unwrap_err() {
@@ -672,6 +686,7 @@ pub(super) mod tests {
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level: QuoteLevel::Full,
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indent: Indent::Owned(Indentation::new(b' ', 2)),
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write_indent: false,
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expand_empty_elements: false,
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};
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$data.serialize(ser).unwrap();
@@ -692,6 +707,7 @@ pub(super) mod tests {
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level: QuoteLevel::Full,
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indent: Indent::Owned(Indentation::new(b' ', 2)),
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write_indent: false,
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expand_empty_elements: false,
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};
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match $data.serialize(ser).unwrap_err() {

‎src/se/element.rs‎

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Original file line numberDiff line numberDiff line change
@@ -397,6 +397,7 @@ impl<'w, 'k, W: Write> Struct<'w, 'k, W> {
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level: self.ser.ser.level,
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indent: self.ser.ser.indent.borrow(),
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write_indent: true,
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expand_empty_elements: false,
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};
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if key == TEXT_KEY {
@@ -574,6 +575,7 @@ mod tests {
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level: QuoteLevel::Full,
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indent: Indent::None,
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write_indent: false,
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expand_empty_elements: false,
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},
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key: XmlName("root"),
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};
@@ -597,6 +599,7 @@ mod tests {
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level: QuoteLevel::Full,
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indent: Indent::None,
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write_indent: false,
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expand_empty_elements: false,
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},
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key: XmlName("root"),
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};
@@ -1533,6 +1536,7 @@ mod tests {
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level: QuoteLevel::Full,
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indent: Indent::Owned(Indentation::new(b' ', 2)),
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write_indent: false,
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expand_empty_elements: false,
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},
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key: XmlName("root"),
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};
@@ -1556,6 +1560,7 @@ mod tests {
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level: QuoteLevel::Full,
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indent: Indent::Owned(Indentation::new(b' ', 2)),
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write_indent: false,
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expand_empty_elements: false,
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},
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key: XmlName("root"),
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};
@@ -2533,4 +2538,76 @@ mod tests {
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</root>");
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}
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}
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mod expand_empty_elements {
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use super::*;
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use pretty_assertions::assert_eq;
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2546+
/// Checks that given `$data` successfully serialized as `$expected`
2547+
macro_rules! serialize_as {
2548+
($name:ident: $data:expr => $expected:expr) => {
2549+
#[test]
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fn $name() {
2551+
let mut buffer = String::new();
2552+
let ser = ElementSerializer {
2553+
ser: ContentSerializer {
2554+
writer: &mut buffer,
2555+
level: QuoteLevel::Full,
2556+
indent: Indent::None,
2557+
write_indent: false,
2558+
expand_empty_elements: true,
2559+
},
2560+
key: XmlName("root"),
2561+
};
2562+
2563+
$data.serialize(ser).unwrap();
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assert_eq!(buffer, $expected);
2565+
}
2566+
};
2567+
}
2568+
2569+
/// Checks that attempt to serialize given `$data` results to a
2570+
/// serialization error `$kind` with `$reason`
2571+
macro_rules! err {
2572+
($name:ident: $data:expr => $kind:ident($reason:literal)) => {
2573+
#[test]
2574+
fn $name() {
2575+
let mut buffer = String::new();
2576+
let ser = ElementSerializer {
2577+
ser: ContentSerializer {
2578+
writer: &mut buffer,
2579+
level: QuoteLevel::Full,
2580+
indent: Indent::None,
2581+
write_indent: false,
2582+
expand_empty_elements: false,
2583+
},
2584+
key: XmlName("root"),
2585+
};
2586+
2587+
match $data.serialize(ser).unwrap_err() {
2588+
DeError::$kind(e) => assert_eq!(e, $reason),
2589+
e => panic!(
2590+
"Expected `{}({})`, found `{:?}`",
2591+
stringify!($kind),
2592+
$reason,
2593+
e
2594+
),
2595+
}
2596+
// We can write something before fail
2597+
// assert_eq!(buffer, "");
2598+
}
2599+
};
2600+
}
2601+
2602+
serialize_as!(option_some_empty: Some("") => "<root></root>");
2603+
serialize_as!(option_some_empty_str: Some("") => "<root></root>");
2604+
2605+
serialize_as!(unit: () => "<root></root>");
2606+
serialize_as!(unit_struct: Unit => "<root></root>");
2607+
serialize_as!(unit_struct_escaped: UnitEscaped => "<root></root>");
2608+
2609+
serialize_as!(enum_unit: Enum::Unit => "<Unit></Unit>");
2610+
err!(enum_unit_escaped: Enum::UnitEscaped
2611+
=> Unsupported("character `<` is not allowed at the start of an XML name `<\"&'>`"));
2612+
}
25362613
}

‎src/se/mod.rs‎

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Original file line numberDiff line numberDiff line change
@@ -458,6 +458,7 @@ impl<'w, 'r, W: Write> Serializer<'w, 'r, W> {
458458
level: QuoteLevel::Full,
459459
indent: Indent::None,
460460
write_indent: false,
461+
expand_empty_elements: false,
461462
},
462463
root_tag: None,
463464
}
@@ -522,11 +523,45 @@ impl<'w, 'r, W: Write> Serializer<'w, 'r, W> {
522523
level: QuoteLevel::Full,
523524
indent: Indent::None,
524525
write_indent: false,
526+
expand_empty_elements: false,
525527
},
526528
root_tag: root_tag.map(|tag| XmlName::try_from(tag)).transpose()?,
527529
})
528530
}
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532+
/// Enable or disable expansion of empty elements. Defaults to `false`.
533+
///
534+
/// # Examples
535+
///
536+
/// ```
537+
/// # use pretty_assertions::assert_eq;
538+
/// # use serde::Serialize;
539+
/// # use quick_xml::se::Serializer;
540+
///
541+
/// #[derive(Debug, PartialEq, Serialize)]
542+
/// struct Struct {
543+
/// question: Option<String>,
544+
/// }
545+
///
546+
/// let mut buffer = String::new();
547+
/// let mut ser = Serializer::new(&mut buffer);
548+
/// ser.expand_empty_elements(true);
549+
///
550+
/// let data = Struct {
551+
/// question: None,
552+
/// };
553+
///
554+
/// data.serialize(ser).unwrap();
555+
/// assert_eq!(
556+
/// buffer,
557+
/// "<Struct><question></question></Struct>"
558+
/// );
559+
/// ```
560+
pub fn expand_empty_elements(&mut self, expand: bool) -> &mut Self {
561+
self.ser.expand_empty_elements = expand;
562+
self
563+
}
564+
530565
/// Configure indent for a serializer
531566
pub fn indent(&mut self, indent_char: char, indent_size: usize) -> &mut Self {
532567
self.ser.indent = Indent::Owned(Indentation::new(indent_char as u8, indent_size));

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