Implement support for recursive input types

Author: tomhoule

graphql_client/tests/input_object_variables.rs

@@ -34,7 +34,7 @@ type Email = String;
 #[graphql(
     query_path = "tests/input_object_variables/input_object_variables_query_defaults.graphql",
     schema_path = "tests/input_object_variables/input_object_variables_schema.graphql",
-    response_derives = "Debug"
+    response_derives = "Debug, PartialEq"
 )]
 pub struct DefaultInputObjectVariablesQuery;
 
@@ -48,3 +48,29 @@ fn input_object_variables_default() {
 
     assert_eq!(out, r#"{"msg":{"content":null,"to":{"category":null,"email":"rosa.luxemburg@example.com","name":null}}}"#);
 }
+
+#[derive(GraphQLQuery)]
+#[graphql(
+    query_path = "tests/input_object_variables/input_object_variables_query.graphql",
+    schema_path = "tests/input_object_variables/input_object_variables_schema.graphql",
+    response_derives = "Debug, PartialEq"
+)]
+pub struct RecursiveInputQuery;
+
+#[test]
+fn recursive_input_objects_can_be_constructed() {
+    use recursive_input_query::*;
+
+    RecursiveInput {
+        head: "hello".to_string(),
+        tail: Box::new(None),
+    };
+
+    RecursiveInput {
+        head: "hi".to_string(),
+        tail: Box::new(Some(RecursiveInput {
+            head: "this is crazy".to_string(),
+            tail: Box::new(None),
+        })),
+    };
+}

graphql_client/tests/input_object_variables/input_object_variables_query.graphql

@@ -3,3 +3,7 @@ query VariablesQuery($msg: Message) {
     result
   }
 }
+
+query RecursiveInputQuery($input: RecursiveInput!) {
+  saveRecursiveInput(recursiveInput: $input)
+}

graphql_client/tests/input_object_variables/input_object_variables_schema.graphql

@@ -24,8 +24,14 @@ input Options {
   pgpSignature: Boolean
 }
 
+input RecursiveInput {
+  head: String!
+  tail: RecursiveInput
+}
+
 type InputObjectVariablesQuery {
   echo(message: Message!, options: Options = { pgpSignature: true }): EchoResult
+  saveRecursiveInput(recursiveInput: RecursiveInput!): Category
 }
 
 type EchoResult {

graphql_client_codegen/src/field_type.rs

@@ -75,6 +75,17 @@ impl<'a> FieldType<'a> {
             _ => false,
         }
     }
+
+    /// A type is indirected if it is a (flat or nested) list type, optional or not.
+    ///
+    /// We use this to determine whether a type needs to be boxed for recursion.
+    pub fn is_indirected(&self) -> bool {
+        match self {
+            FieldType::Vector(_) => true,
+            FieldType::Named(_) => false,
+            FieldType::Optional(inner) => inner.is_indirected(),
+        }
+    }
 }
 
 impl<'schema> ::std::convert::From<&'schema graphql_parser::schema::Type> for FieldType<'schema> {

graphql_client_codegen/src/inputs.rs

@@ -36,6 +36,14 @@ impl<'schema> GqlInput<'schema> {
         fields.sort_unstable_by(|a, b| a.name.cmp(&b.name));
         let fields = fields.iter().map(|field| {
             let ty = field.type_.to_rust(&context, "");
+
+            // If the type is recursive, we have to box it
+            let ty = if field.type_.is_indirected() || field.type_.inner_name_str() != self.name {
+                ty
+            } else {
+                quote! { Box<#ty> }
+            };
+
             context.schema.require(&field.type_.inner_name_str());
             let original_name = &field.name;
             let snake_case_name = field.name.to_snake_case();