Add "skip_serializing" attribute

If it is present on a field, that field should not be included in the output
If both "skip_serializing" and "skip_serializing_if" are present,
"skip_serializing" should take precedent.

yaserde_derive/src/common/attribute.rs

@@ -12,6 +12,7 @@ pub struct YaSerdeAttribute {
   pub namespaces: BTreeMap<Option<String>, String>,
   pub prefix: Option<String>,
   pub rename: Option<String>,
+  pub skip_serializing: bool,
   pub skip_serializing_if: Option<String>,
   pub text: bool,
 }
@@ -39,6 +40,7 @@ impl YaSerdeAttribute {
     let mut namespaces = BTreeMap::new();
     let mut prefix = None;
     let mut rename = None;
+    let mut skip_serializing = false;
     let mut skip_serializing_if = None;
     let mut text = false;
 
@@ -80,6 +82,9 @@ impl YaSerdeAttribute {
                 "rename" => {
                   rename = get_value(&mut attr_iter);
                 }
+                "skip_serializing" => {
+                  skip_serializing = true;
+                }
                 "skip_serializing_if" => {
                   skip_serializing_if = get_value(&mut attr_iter);
                 }
@@ -102,6 +107,7 @@ impl YaSerdeAttribute {
       namespaces,
       prefix,
       rename,
+      skip_serializing,
       skip_serializing_if,
       text,
     }
@@ -177,6 +183,7 @@ fn parse_empty_attributes() {
       namespaces: BTreeMap::new(),
       prefix: None,
       rename: None,
+      skip_serializing: false,
       skip_serializing_if: None,
       text: false,
     },
@@ -226,6 +233,7 @@ fn parse_attributes() {
       namespaces: BTreeMap::new(),
       prefix: None,
       rename: None,
+      skip_serializing: false,
       skip_serializing_if: None,
       text: false,
     },
@@ -275,6 +283,7 @@ fn only_parse_yaserde_attributes() {
       namespaces: BTreeMap::new(),
       prefix: None,
       rename: None,
+      skip_serializing: false,
       skip_serializing_if: None,
       text: false,
     },
@@ -327,6 +336,7 @@ fn parse_attributes_with_values() {
       namespaces,
       prefix: None,
       rename: None,
+      skip_serializing: false,
       skip_serializing_if: None,
       text: false,
     },

yaserde_derive/src/common/field.rs

@@ -40,6 +40,10 @@ impl YaSerdeField {
     self.syn_field.ident.clone()
   }
 
+  pub fn is_skip_serializing(&self) -> bool {
+    self.attributes.skip_serializing
+  }
+
   pub fn get_value_label(&self) -> Option<syn::Ident> {
     self
       .syn_field

yaserde_derive/src/ser/element.rs

@@ -47,18 +47,20 @@ pub fn condition_generator(label: &Option<Ident>, field: &YaSerdeField) -> Token
     .get_default_function()
     .map(|default_function| quote!(self.#label != #default_function()));
 
+  let skip_serializing = field.is_skip_serializing();
+
   field
     .get_skip_serializing_if_function()
     .map(|skip_if_function| {
       if let Some(prev_conditions) = &default_condition {
-        quote!(if !self.#skip_if_function(&self.#label) && #prev_conditions)
+        quote!(if !#skip_serializing && !self.#skip_if_function(&self.#label) && #prev_conditions)
       } else {
-        quote!(if !self.#skip_if_function(&self.#label))
+        quote!(if !#skip_serializing && !self.#skip_if_function(&self.#label))
       }
     })
     .unwrap_or_else(|| {
       default_condition
-        .map(|condition| quote!(if #condition))
-        .unwrap_or_default()
+        .map(|condition| quote!(if !#skip_serializing && #condition))
+        .unwrap_or(quote!(if !#skip_serializing))
     })
 }