diff --git a/google-apis-common/src/serde.rs b/google-apis-common/src/serde.rs
index a34d4318ad..e7de0b1c4e 100644
--- a/google-apis-common/src/serde.rs
+++ b/google-apis-common/src/serde.rs
@@ -97,7 +97,7 @@ pub mod duration {
         }
     }
 
-    fn duration_to_string(duration: &Duration) -> String {
+    pub fn to_string(duration: &Duration) -> String {
         let seconds = duration.num_seconds();
         let nanoseconds = (*duration - Duration::seconds(seconds))
             .num_nanoseconds()
@@ -121,7 +121,7 @@ pub mod duration {
         where
             S: serde::Serializer,
         {
-            s.serialize_str(&duration_to_string(value))
+            s.serialize_str(&to_string(value))
         }
     }
 
@@ -142,12 +142,16 @@ pub mod urlsafe_base64 {
 
     pub struct Wrapper;
 
+    pub fn to_string(bytes: &Vec<u8>) -> String {
+        base64::encode_config(bytes, base64::URL_SAFE)
+    }
+
     impl SerializeAs<Vec<u8>> for Wrapper {
         fn serialize_as<S>(value: &Vec<u8>, s: S) -> Result<S::Ok, S::Error>
         where
             S: Serializer,
         {
-            s.serialize_str(&base64::encode_config(value, base64::URL_SAFE))
+            s.serialize_str(&to_string(value))
         }
     }
 
@@ -162,6 +166,10 @@ pub mod urlsafe_base64 {
     }
 }
 
+pub fn datetime_to_string(datetime: &chrono::DateTime<chrono::offset::Utc>) -> String {
+    datetime.to_rfc3339_opts(chrono::SecondsFormat::Millis, true)
+}
+
 #[cfg(test)]
 mod test {
     use super::{duration, urlsafe_base64};
diff --git a/src/generator/lib/util.py b/src/generator/lib/util.py
index 5379c04a55..a9f789c3e7 100644
--- a/src/generator/lib/util.py
+++ b/src/generator/lib/util.py
@@ -1241,5 +1241,15 @@ def size_to_bytes(size):
     # end handle errors gracefully
 
 
+def string_impl(p):
+    return {
+        "google-duration": "::client::serde::duration::to_string",
+        "byte": "::client::serde::urlsafe_base64::to_string",
+        "google-datetime": "::client::serde::datetime_to_string",
+        "date-time": "::client::serde::datetime_to_string",
+        "google-fieldmask": "(|x: &client::FieldMask| x.to_string())"
+    }.get(p.get("format"), "(|x: &dyn std::fmt::Display| x.to_string())")
+
+
 if __name__ == '__main__':
     raise AssertionError('For import only')
diff --git a/src/generator/templates/api/lib/mbuild.mako b/src/generator/templates/api/lib/mbuild.mako
index 1c970b828e..e6db099470 100644
--- a/src/generator/templates/api/lib/mbuild.mako
+++ b/src/generator/templates/api/lib/mbuild.mako
@@ -11,7 +11,7 @@
                       DELEGATE_PROPERTY_NAME, struct_type_bounds_s, scope_url_to_variant,
                       re_find_replacements, ADD_PARAM_FN, ADD_PARAM_MEDIA_EXAMPLE, upload_action_fn, METHODS_RESOURCE,
                       method_name_to_variant, size_to_bytes, method_default_scope,
-                      is_repeated_property, setter_fn_name, ADD_SCOPE_FN, rust_doc_sanitize, items)
+                      is_repeated_property, setter_fn_name, ADD_SCOPE_FN, rust_doc_sanitize, items, string_impl)
 
     def get_parts(part_prop):
         if not part_prop:
@@ -534,6 +534,7 @@ match result {
         % for p in field_params:
 <%
     pname = 'self.' + property(p.name)    # property identifier
+    to_string_impl = string_impl(p)
 %>\
         ## parts can also be derived from the request, but we do that only if it's not set
         % if p.name == 'part' and request_value:
@@ -556,15 +557,15 @@ match result {
         % if p.get('repeated', False):
         if ${pname}.len() > 0 {
             for f in ${pname}.iter() {
-                params.push(("${p.name}", f.to_string()));
+                params.push(("${p.name}", ${to_string_impl}(f)));
             }
         }
         % elif not is_required_property(p):
-        if let Some(value) = ${pname} {
-            params.push(("${p.name}", value.to_string()));
+        if let Some(value) = ${pname}.as_ref() {
+            params.push(("${p.name}", ${to_string_impl}(value)));
         }
         % else:
-        params.push(("${p.name}", ${pname}.to_string()));
+        params.push(("${p.name}", ${to_string_impl}(&${pname})));
         % endif
         % endfor
         ## Additional params - may not overlap with optional params