Serializer namespaces and attributes (#13)

instant-xml-macros/src/lib.rs

@@ -3,7 +3,7 @@ extern crate proc_macro;
 mod de;
 mod se;
 
-use std::collections::{BTreeSet, HashMap};
+use std::collections::HashMap;
 
 use proc_macro2::TokenStream;
 use quote::quote;
@@ -33,19 +33,22 @@ pub(crate) fn get_namespaces(
 
     if name == "namespace" {
         let mut iter = list.nested.iter();
-        if let Some(NestedMeta::Lit(Lit::Str(v))) = iter.next() {
+        let mut next = iter.next();
+        if let Some(NestedMeta::Lit(Lit::Str(v))) = next {
             default_namespace = v.value();
+            next = iter.next();
         }
 
-        for item in iter {
+        while let Some(value) = next {
-            if let NestedMeta::Meta(Meta::NameValue(key)) = item {
+            if let NestedMeta::Meta(Meta::NameValue(key)) = value {
                 if let Lit::Str(value) = &key.lit {
                     other_namespaces
                         .insert(key.path.get_ident().unwrap().to_string(), value.value());
+                    next = iter.next();
                     continue;
                 }
             }
-            panic!("Wrong data");
+            panic!("Wrong data")
         }
     }
 
@@ -102,17 +105,19 @@ pub fn to_xml(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let ast = parse_macro_input!(input as syn::DeriveInput);
     let ident = &ast.ident;
     let root_name = ident.to_string();
-    let mut missing_prefixes = BTreeSet::new();
     let mut serializer = Serializer::new(&ast.attrs);
-    let mut output = TokenStream::new();
-    serializer.add_header(&mut output);
 
+    let mut header = TokenStream::new();
+    serializer.add_header(&mut header);
+
+    let mut body = TokenStream::new();
+    let mut attributes = TokenStream::new();
     match &ast.data {
         syn::Data::Struct(ref data) => {
             match data.fields {
                 syn::Fields::Named(ref fields) => {
                     fields.named.iter().for_each(|field| {
-                        serializer.process_named_field(field, &mut output, &mut missing_prefixes);
+                        serializer.process_named_field(field, &mut body, &mut attributes);
                     });
                 }
                 syn::Fields::Unnamed(_) => todo!(),
@@ -122,39 +127,34 @@ pub fn to_xml(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
         _ => todo!(),
     };
 
-    serializer.add_footer(&root_name, &mut output);
+    let mut footer = TokenStream::new();
+    serializer.add_footer(&root_name, &mut footer);
 
-    let current_prefixes = serializer.keys_set();
+    let current_namespaces = serializer.namespaces_token();
 
     proc_macro::TokenStream::from(quote!(
         impl ToXml for #ident {
-            fn serialize<W>(&self, serializer: &mut instant_xml::Serializer<W>, _field_data: Option<&instant_xml::FieldContext>) -> Result<(), instant_xml::Error>
+            fn serialize<W>(&self, serializer: &mut instant_xml::Serializer<W>) -> Result<(), instant_xml::Error>
             where
                 W: std::fmt::Write,
             {
+                println!("ident: {}", #root_name);
+                let _ = serializer.consume_field_context();
                 let mut field_context = instant_xml::FieldContext {
                     name: #root_name,
                     attribute: None,
                 };
 
-                // Check if prefix exist
+                #attributes
-                #(
-                    if serializer.parent_prefixes.get(#missing_prefixes).is_none() {
-                        return Err(instant_xml::Error::WrongNamespace);
-                    }
-                )*;
 
-                // Adding current prefixes
+                #header
-                let mut to_remove: Vec<&str> = Vec::new();
+                #current_namespaces
-                #(if serializer.parent_prefixes.insert(#current_prefixes) {
+                #body
-                    to_remove.push(#current_prefixes);
+                #footer
-                };)*;
 
-                #output
+                // Removing current namespaces
-
-                // Removing current prefixes
                 for it in to_remove {
-                    serializer.parent_prefixes.remove(it);
+                    serializer.parent_namespaces.remove(it);
                 }
 
                 Ok(())

instant-xml-macros/src/se.rs

@@ -1,4 +1,4 @@
-use std::collections::{BTreeSet, HashMap};
+use std::collections::HashMap;
 
 use proc_macro2::TokenStream;
 use quote::quote;
@@ -20,40 +20,43 @@ impl<'a> Serializer {
         }
     }
 
-    pub fn keys_set(&self) -> BTreeSet<&str> {
-        self.other_namespaces
-            .iter()
-            .map(|(k, _)| k.as_str())
-            .collect()
-    }
-
     pub fn add_header(&mut self, output: &'a mut TokenStream) {
         output.extend(quote!(
             serializer.output.write_char('<')?;
             serializer.output.write_str(field_context.name)?;
         ));
 
-        if !self.default_namespace.is_empty() {
+        let default_namespace = &self.default_namespace;
-            let default_namespace = &self.default_namespace;
+        output.extend(quote!(
-            output.extend(quote!(
+            // Check if parent default namespace equals
+            if serializer.parent_default_namespace() != #default_namespace {
                 serializer.output.write_str(" xmlns=\"")?;
                 serializer.output.write_str(#default_namespace)?;
                 serializer.output.write_char('\"')?;
-            ));
+            }
-        }
+            serializer.update_parent_default_namespace(#default_namespace);
+        ));
 
         let mut sorted_values: Vec<_> = self.other_namespaces.iter().collect();
         sorted_values.sort();
 
         for (key, val) in sorted_values {
             output.extend(quote!(
-                serializer.output.write_str(" xmlns:")?;
+                if serializer.parent_namespaces.get(#val).is_none() {
-                serializer.output.write_str(#key)?;
+                    serializer.output.write_str(" xmlns:")?;
-                serializer.output.write_str("=\"")?;
+                    serializer.output.write_str(#key)?;
-                serializer.output.write_str(#val)?;
+                    serializer.output.write_str("=\"")?;
-                serializer.output.write_char('\"')?;
+                    serializer.output.write_str(#val)?;
+                    serializer.output.write_char('\"')?;
+                }
             ));
         }
+
+        // Attributes
+        output.extend(quote!(
+            serializer.consume_current_attributes()?;
+        ));
+
         output.extend(quote!(
             serializer.output.write_char('>')?;
         ));
@@ -64,45 +67,97 @@ impl<'a> Serializer {
             serializer.output.write_str("</")?;
             serializer.output.write_str(#root_name)?;
             serializer.output.write_char('>')?;
+            serializer.retrive_parent_default_namespace();
         ));
     }
 
     pub fn process_named_field(
         &mut self,
         field: &syn::Field,
-        output: &'a mut TokenStream,
+        body: &mut TokenStream,
-        missing_prefixes: &'a mut BTreeSet<String>,
+        attributes: &mut TokenStream,
     ) {
         let name = field.ident.as_ref().unwrap().to_string();
         let field_value = field.ident.as_ref().unwrap();
 
-        output.extend(quote!(
+        let declaration = quote!(
             let mut field = instant_xml::FieldContext {
                 name: #name,
                 attribute: None,
             };
-        ));
+        );
 
-        match retrieve_field_attribute(field) {
+        let stream_ref = match retrieve_field_attribute(field) {
-            Some(FieldAttribute::Namespace(namespace_key)) => {
+            Some(FieldAttribute::Namespace(namespace)) => {
-                output.extend(quote!(
+                body.extend(quote!(
-                    field.attribute = Some(instant_xml::FieldAttribute::Namespace(#namespace_key));
+                    #declaration
+                    // // Check if such namespace already exist, if so change it to use its prefix
+                    // match serializer.parent_namespaces.get(#namespace) {
+                    //     Some(key) => field.attribute = Some(instant_xml::FieldAttribute::Prefix(key)),
+                    //     None => field.attribute = Some(instant_xml::FieldAttribute::Namespace(#namespace)),
+                    // };
+                    field.attribute = Some(instant_xml::FieldAttribute::Namespace(#namespace));
                 ));
+                body
             }
             Some(FieldAttribute::PrefixIdentifier(prefix_key)) => {
-                output.extend(quote!(
+                match self.other_namespaces.get(&prefix_key) {
-                    field.attribute = Some(instant_xml::FieldAttribute::Prefix(#prefix_key));
+                    Some(val) => {
-                ));
+                        body.extend(quote!(
+                            #declaration
 
-                if self.other_namespaces.get(&prefix_key).is_none() {
+                            // Check if such namespace already exist, if so change its prefix to parent prefix
-                    missing_prefixes.insert(prefix_key);
+                            let prefix_key = match serializer.parent_namespaces.get(#val) {
+                                Some(key) => key,
+                                None => #prefix_key,
+                            };
+                        ));
+                    }
+                    None => panic!("Prefix not defined: {}", prefix_key),
                 };
+
+                body.extend(quote!(
+                    field.attribute = Some(instant_xml::FieldAttribute::Prefix(prefix_key));
+                ));
+                body
+            }
+            Some(FieldAttribute::Attribute) => {
+                attributes.extend(quote!(
+                    #declaration
+
+                    serializer.add_attribute_key(&#name);
+                    field.attribute = Some(instant_xml::FieldAttribute::Attribute);
+                ));
+                attributes
+            }
+            _ => {
+                body.extend(quote!(
+                    #declaration
+                ));
+                body
             }
-            _ => {}
         };
 
-        output.extend(quote!(
+        stream_ref.extend(quote!(
-            self.#field_value.serialize(serializer, Some(&field))?;
+            serializer.set_field_context(field)?;
+            self.#field_value.serialize(serializer)?;
         ));
     }
+
+    pub fn namespaces_token(&self) -> TokenStream {
+        let mut namespaces = quote!(
+            let mut to_remove: Vec<&str> = Vec::new();
+        );
+        for (k, v) in self.other_namespaces.iter() {
+            namespaces.extend(quote!(
+                // Only adding to HashMap if namespace do not exist, if it exist it will use the parent defined prefix
+                if let std::collections::hash_map::Entry::Vacant(v) = serializer.parent_namespaces.entry(#v) {
+                    v.insert(#k);
+                    // Will remove added namespaces when going "up"
+                    to_remove.push(#v);
+                };
+            ))
+        }
+        namespaces
+    }
 }

instant-xml/src/lib.rs

@@ -1,4 +1,4 @@
-use std::collections::{BTreeSet, HashMap};
+use std::collections::HashMap;
 use std::fmt;
 
 use thiserror::Error;
@@ -29,15 +29,11 @@ pub trait ToXml {
     fn to_xml(&self) -> Result<String, Error> {
         let mut output = String::new();
         let mut serializer = Serializer::new(&mut output);
-        self.serialize(&mut serializer, None)?;
+        self.serialize(&mut serializer)?;
         Ok(output)
     }
 
-    fn serialize<W>(
+    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
-        &self,
-        serializer: &mut Serializer<W>,
-        field_context: Option<&FieldContext>,
-    ) -> Result<(), Error>
     where
         W: fmt::Write;
 }
@@ -45,19 +41,22 @@ pub trait ToXml {
 macro_rules! to_xml_for_number {
     ($typ:ty) => {
         impl ToXml for $typ {
-            fn serialize<W>(
+            fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
-                &self,
-                serializer: &mut Serializer<W>,
-                field_context: Option<&FieldContext>,
-            ) -> Result<(), Error>
             where
                 W: fmt::Write,
             {
-                match field_context {
+                match serializer.consume_field_context() {
                     Some(field_context) => {
-                        serializer.add_open_tag(field_context)?;
+                        match field_context.attribute {
-                        write!(serializer.output, "{}", &self)?;
+                            Some(FieldAttribute::Attribute) => {
-                        serializer.add_close_tag(field_context)?;
+                                serializer.add_attribute_value(&self.to_string());
+                            }
+                            _ => {
+                                serializer.add_open_tag(&field_context)?;
+                                write!(serializer.output, "{}", &self)?;
+                                serializer.add_close_tag(field_context)?;
+                            }
+                        }
                         Ok(())
                     }
                     None => Err(Error::UnexpectedValue),
@@ -77,11 +76,7 @@ to_xml_for_number!(u32);
 to_xml_for_number!(u64);
 
 impl ToXml for bool {
-    fn serialize<W>(
+    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
-        &self,
-        serializer: &mut Serializer<W>,
-        field_context: Option<&FieldContext>,
-    ) -> Result<(), Error>
     where
         W: fmt::Write,
     {
@@ -90,11 +85,18 @@ impl ToXml for bool {
             false => "false",
         };
 
-        match field_context {
+        match serializer.consume_field_context() {
             Some(field_context) => {
-                serializer.add_open_tag(field_context)?;
+                match field_context.attribute {
-                serializer.output.write_str(value)?;
+                    Some(FieldAttribute::Attribute) => {
-                serializer.add_close_tag(field_context)?;
+                        serializer.add_attribute_value(value);
+                    }
+                    _ => {
+                        serializer.add_open_tag(&field_context)?;
+                        serializer.output.write_str(value)?;
+                        serializer.add_close_tag(field_context)?;
+                    }
+                }
                 Ok(())
             }
             None => Err(Error::UnexpectedValue),
@@ -103,19 +105,22 @@ impl ToXml for bool {
 }
 
 impl ToXml for String {
-    fn serialize<W>(
+    fn serialize<W>(&self, serializer: &mut Serializer<W>) -> Result<(), Error>
-        &self,
-        serializer: &mut Serializer<W>,
-        field_context: Option<&FieldContext>,
-    ) -> Result<(), Error>
     where
         W: fmt::Write,
     {
-        match field_context {
+        match serializer.consume_field_context() {
             Some(field_context) => {
-                serializer.add_open_tag(field_context)?;
+                match field_context.attribute {
-                serializer.output.write_str(self)?;
+                    Some(FieldAttribute::Attribute) => {
-                serializer.add_close_tag(field_context)?;
+                        serializer.add_attribute_value(self);
+                    }
+                    _ => {
+                        serializer.add_open_tag(&field_context)?;
+                        serializer.output.write_str(self)?;
+                        serializer.add_close_tag(field_context)?;
+                    }
+                }
                 Ok(())
             }
             None => Err(Error::UnexpectedValue),
@@ -127,20 +132,80 @@ pub struct Serializer<'xml, W>
 where
     W: fmt::Write,
 {
+    // For parent namespaces the key is the namespace and the value is the prefix. We are adding to map
+    // only if the namespaces do not exist, if it does exist then we are using an already defined parent prefix.
     #[doc(hidden)]
-    pub parent_prefixes: BTreeSet<&'xml str>,
+    pub parent_namespaces: HashMap<&'xml str, &'xml str>,
     #[doc(hidden)]
     pub output: &'xml mut W,
+
+    parent_default_namespace: &'xml str,
+    parent_default_namespace_to_revert: &'xml str,
+    current_attributes: String,
+    next_field_context: Option<FieldContext<'xml>>,
 }
 
 impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
     pub fn new(output: &'xml mut W) -> Self {
         Self {
-            parent_prefixes: BTreeSet::new(),
+            parent_namespaces: HashMap::new(),
             output,
+            parent_default_namespace: "",
+            parent_default_namespace_to_revert: "",
+            next_field_context: None,
+            current_attributes: String::new(),
         }
     }
 
+    pub fn consume_current_attributes(&mut self) -> Result<(), Error> {
+        self.output.write_str(&self.current_attributes)?;
+        self.current_attributes.clear();
+        Ok(())
+    }
+
+    pub fn add_attribute_key(&mut self, attr_key: &str) {
+        self.current_attributes.push(' ');
+        self.current_attributes.push_str(attr_key);
+        self.current_attributes.push('=');
+    }
+
+    pub fn add_attribute_value(&mut self, attr_value: &str) {
+        self.current_attributes.push('"');
+        self.current_attributes.push_str(attr_value);
+        self.current_attributes.push('"');
+    }
+
+    pub fn set_field_context(&mut self, field_context: FieldContext<'xml>) -> Result<(), Error> {
+        if self.next_field_context.is_some() {
+            return Err(Error::UnexpectedState);
+        };
+
+        self.next_field_context = Some(field_context);
+        Ok(())
+    }
+
+    pub fn consume_field_context(&mut self) -> Option<FieldContext<'xml>> {
+        self.next_field_context.take()
+    }
+
+    pub fn set_parent_default_namespace(&mut self, namespace: &'xml str) -> Result<(), Error> {
+        self.parent_default_namespace = namespace;
+        Ok(())
+    }
+
+    pub fn parent_default_namespace(&self) -> &'xml str {
+        self.parent_default_namespace
+    }
+
+    pub fn update_parent_default_namespace(&mut self, namespace: &'xml str) {
+        self.parent_default_namespace_to_revert = self.parent_default_namespace;
+        self.parent_default_namespace = namespace;
+    }
+
+    pub fn retrive_parent_default_namespace(&mut self) {
+        self.parent_default_namespace = self.parent_default_namespace_to_revert;
+    }
+
     fn add_open_tag(&mut self, field_context: &FieldContext) -> Result<(), Error> {
         match field_context.attribute {
             Some(FieldAttribute::Prefix(prefix)) => {
@@ -150,7 +215,9 @@ impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
                 self.output.write_str(field_context.name)?;
                 self.output.write_char('>')?;
             }
-            Some(FieldAttribute::Namespace(namespace)) => {
+            Some(FieldAttribute::Namespace(namespace))
+                if self.parent_default_namespace != namespace =>
+            {
                 self.output.write_char('<')?;
                 self.output.write_str(field_context.name)?;
                 self.output.write_str(" xmlns=\"")?;
@@ -166,7 +233,7 @@ impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
         Ok(())
     }
 
-    fn add_close_tag(&mut self, field_context: &FieldContext) -> Result<(), Error> {
+    fn add_close_tag(&mut self, field_context: FieldContext) -> Result<(), Error> {
         match field_context.attribute {
             Some(FieldAttribute::Prefix(prefix)) => {
                 self.output.write_str("</")?;
@@ -188,6 +255,7 @@ impl<'xml, W: std::fmt::Write> Serializer<'xml, W> {
 pub enum FieldAttribute<'xml> {
     Prefix(&'xml str),
     Namespace(&'xml str),
+    Attribute,
 }
 
 pub struct FieldContext<'xml> {

instant-xml/tests/all.rs

@@ -1,16 +1,5 @@
 use instant_xml::{Error, FromXml, ToXml};
-
+//TODO: Add compile time errors check?
-#[derive(Debug, Eq, PartialEq, ToXml)]
-struct Nested {
-    #[xml(namespace(bar))]
-    flag: bool,
-}
-
-#[derive(Debug, Eq, PartialEq, ToXml)]
-struct NestedWrongPrefix {
-    #[xml(namespace(dar))]
-    flag: bool,
-}
 
 #[derive(Debug, Eq, PartialEq, ToXml)]
 struct Unit;
@@ -22,7 +11,7 @@ fn unit() {
 }
 
 #[derive(Debug, Eq, PartialEq, ToXml)]
-#[xml(namespace("URI", bar = "BAZ", foo = "BAR"))]
+#[xml(namespace(bar = "BAZ", foo = "BAR"))]
 struct StructWithNamedFields {
     flag: bool,
     #[xml(namespace(bar))]
@@ -31,6 +20,11 @@ struct StructWithNamedFields {
     number: i32,
 }
 
+// Tests:
+// - Empty default namespace
+// - Prefix namespace
+// - Direct namespace
+
 #[test]
 fn struct_with_named_fields() {
     assert_eq!(
@@ -41,52 +35,104 @@ fn struct_with_named_fields() {
         }
         .to_xml()
         .unwrap(),
-        "<StructWithNamedFields xmlns=\"URI\" xmlns:bar=\"BAZ\" xmlns:foo=\"BAR\"><flag>true</flag><bar:string>test</bar:string><number xmlns=\"typo\">1</number></StructWithNamedFields>"
+        "<StructWithNamedFields xmlns:bar=\"BAZ\" xmlns:foo=\"BAR\"><flag>true</flag><bar:string>test</bar:string><number xmlns=\"typo\">1</number></StructWithNamedFields>"
     );
 }
 
+#[derive(Debug, Eq, PartialEq, ToXml)]
+#[xml(namespace("URI", dar = "BAZ", internal = "INTERNAL"))]
+struct Nested {
+    #[xml(namespace(dar))]
+    flag_parent_prefix: bool,
+    #[xml(namespace(internal))]
+    flag_internal_prefix: bool,
+}
+
 #[derive(Debug, Eq, PartialEq, ToXml)]
 #[xml(namespace("URI", bar = "BAZ", foo = "BAR"))]
 struct StructWithCustomField {
+    #[xml(attribute)]
+    int_attribute: i32,
+    #[xml(namespace("BAZ"))]
+    flag_direct_namespace_same_the_same_as_prefix: bool,
+    #[xml(namespace(bar))]
+    flag_prefix: bool,
+    #[xml(namespace("DIFFERENT"))]
+    flag_direct_namespace: bool,
     test: Nested,
 }
 
+// Tests:
+// - The same direct namespace as the one from prefix
+// - Attribute handling
+// - Omitting redeclared child default namespace
+// - Omitting redeclared child namespace with different prefix
+// - Unique direct namespace
+// - Child unique prefix
+// - Child repeated prefix
+// - Child default namespace the same as parent
 #[test]
 fn struct_with_custom_field() {
     assert_eq!(
         StructWithCustomField {
+            int_attribute: 42,
+            flag_direct_namespace_same_the_same_as_prefix: true,
+            flag_prefix: false,
+            flag_direct_namespace: true,
             test: Nested {
-                flag: true,
+                flag_parent_prefix: true,
+                flag_internal_prefix: false,
             },
         }
         .to_xml()
         .unwrap(),
-        "<StructWithCustomField xmlns=\"URI\" xmlns:bar=\"BAZ\" xmlns:foo=\"BAR\"><Nested><bar:flag>true</bar:flag></Nested></StructWithCustomField>"
+        "<StructWithCustomField xmlns=\"URI\" xmlns:bar=\"BAZ\" xmlns:foo=\"BAR\" int_attribute=\"42\"><flag_direct_namespace_same_the_same_as_prefix xmlns=\"BAZ\">true</flag_direct_namespace_same_the_same_as_prefix><bar:flag_prefix>false</bar:flag_prefix><flag_direct_namespace xmlns=\"DIFFERENT\">true</flag_direct_namespace><Nested xmlns:internal=\"INTERNAL\"><bar:flag_parent_prefix>true</bar:flag_parent_prefix><internal:flag_internal_prefix>false</internal:flag_internal_prefix></Nested></StructWithCustomField>"
-
     );
 }
 
-#[derive(Debug, Eq, PartialEq, ToXml, FromXml)]
+#[derive(Debug, Eq, PartialEq, ToXml)]
-#[xml(namespace("URI", bar = "BAZ"))]
+#[xml(namespace(dar = "BAZ", internal = "INTERNAL"))]
-struct NestedDe {
+struct NestedDifferentNamespace {
-    #[xml(namespace(bar))]
+    #[xml(namespace(dar))]
-    flag: bool,
+    flag_parent_prefix: bool,
+    #[xml(namespace(internal))]
+    flag_internal_prefix: bool,
 }
 
 #[derive(Debug, Eq, PartialEq, ToXml)]
 #[xml(namespace("URI", bar = "BAZ", foo = "BAR"))]
-struct StructWithCustomFieldWrongPrefix {
+struct StructChildNamespaces {
-    test: NestedWrongPrefix,
+    different_child_namespace: NestedDifferentNamespace,
+    same_child_namespace: Nested,
 }
 
+// Tests:
+// - Different child namespace
+// - The same child namespace
 #[test]
-#[should_panic]
+fn struct_child_namespaces() {
-fn struct_with_custom_field_wrong_prefix() {
+    assert_eq!(
-    StructWithCustomFieldWrongPrefix {
+        StructChildNamespaces {
-        test: NestedWrongPrefix { flag: true },
+            different_child_namespace: NestedDifferentNamespace {
-    }
+                flag_parent_prefix: true,
-    .to_xml()
+                flag_internal_prefix: false,
-    .unwrap();
+            },
+            same_child_namespace: Nested {
+                flag_parent_prefix: true,
+                flag_internal_prefix: false,
+            },
+        }
+        .to_xml()
+        .unwrap(),
+        "<StructChildNamespaces xmlns=\"URI\" xmlns:bar=\"BAZ\" xmlns:foo=\"BAR\"><NestedDifferentNamespace xmlns=\"\" xmlns:internal=\"INTERNAL\"><bar:flag_parent_prefix>true</bar:flag_parent_prefix><internal:flag_internal_prefix>false</internal:flag_internal_prefix></NestedDifferentNamespace><Nested xmlns:internal=\"INTERNAL\"><bar:flag_parent_prefix>true</bar:flag_parent_prefix><internal:flag_internal_prefix>false</internal:flag_internal_prefix></Nested></StructChildNamespaces>"
+    );
+}
+
+#[derive(Debug, Eq, PartialEq, FromXml)]
+#[xml(namespace("URI", bar = "BAZ"))]
+struct NestedDe {
+    #[xml(namespace(bar))]
+    flag: bool,
 }
 
 #[derive(Debug, Eq, PartialEq, FromXml)]
@@ -138,7 +184,7 @@ fn struct_with_custom_field_from_xml() {
     );
 }
 
-#[derive(Debug, Eq, PartialEq, ToXml, FromXml)]
+#[derive(Debug, Eq, PartialEq, FromXml)]
 struct NestedWrongNamespace {
     flag: bool,
 }