refs #439. Fix skip_serializing_none for root level variables

graphql_client/tests/skip_serializing_none.rs

@@ -13,6 +13,10 @@ fn skip_serializing_none() {
     use skip_serializing_none_mutation::*;
 
     let query = SkipSerializingNoneMutation::build_query(Variables {
+        optional_int: None,
+        optional_list: None,
+        non_optional_int: 1337,
+        non_optional_list: vec![],
         param: Some(Param {
             data: Author {
                 name: "test".to_owned(),
@@ -25,5 +29,29 @@ fn skip_serializing_none() {
 
     println!("{}", stringified);
 
-    assert!(stringified.contains(r#""data":{"name":"test"}"#));
+    assert!(stringified.contains(r#""param":{"data":{"name":"test"}}"#));
+    assert!(stringified.contains(r#""nonOptionalInt":1337"#));
+    assert!(stringified.contains(r#""nonOptionalList":[]"#));
+    assert!(!stringified.contains(r#""optionalInt""#));
+    assert!(!stringified.contains(r#""optionalList""#));
+
+    let query = SkipSerializingNoneMutation::build_query(Variables {
+        optional_int: Some(42),
+        optional_list: Some(vec![]),
+        non_optional_int: 1337,
+        non_optional_list: vec![],
+        param: Some(Param {
+            data: Author {
+                name: "test".to_owned(),
+                id: None,
+            },
+        }),
+    });
+    let stringified = serde_json::to_string(&query).expect("SkipSerializingNoneMutation is valid");
+    println!("{}", stringified);
+    assert!(stringified.contains(r#""param":{"data":{"name":"test"}}"#));
+    assert!(stringified.contains(r#""nonOptionalInt":1337"#));
+    assert!(stringified.contains(r#""nonOptionalList":[]"#));
+    assert!(stringified.contains(r#""optionalInt":42"#));
+    assert!(stringified.contains(r#""optionalList":[]"#));
 }

graphql_client/tests/skip_serializing_none/query.graphql

@@ -1,4 +1,4 @@
-mutation SkipSerializingNoneMutation($param: Param) {
+mutation SkipSerializingNoneMutation($param: Param, $optionalInt: Int, $optionalList: [Int!], $nonOptionalInt: Int!, $nonOptionalList: [Int!]!) {
   optInput(query: $param) {
     name
     __typename

graphql_client_codegen/src/codegen.rs

@@ -135,10 +135,19 @@ fn generate_variable_struct_field(
     let snake_case_name = variable.name.to_snake_case();
     let safe_name = shared::keyword_replace(&snake_case_name);
     let ident = Ident::new(&safe_name, Span::call_site());
-    let annotation = shared::field_rename_annotation(&variable.name, &safe_name);
+    let rename_annotation = shared::field_rename_annotation(&variable.name, &safe_name);
+    let skip_serializing_annotation = if *options.skip_serializing_none() {
+        if variable.r#type.qualifiers.first() != Some(&GraphqlTypeQualifier::Required) {
+            Some(quote!(#[serde(skip_serializing_if = "Option::is_none")]))
+        } else {
+            None
+        }
+    } else {
+        None
+    };
     let r#type = render_variable_field_type(variable, options, query);
 
-    quote::quote!(#annotation pub #ident : #r#type)
+    quote::quote!(#skip_serializing_annotation #rename_annotation pub #ident : #r#type)
 }
 
 fn generate_scalar_definitions<'a, 'schema: 'a>(