Fix mutation optional variables

schema.gql

@@ -54,6 +54,7 @@ type Query {
 
 type Mutation {
   mutationWithError: MutationWithErrorResult!
+  mutationWithOptionalArgument(field: String): MutationWithErrorResult!
 }
 
 type Subscription {

src/bucklescript/output_bucklescript_encoder.ml

@@ -69,6 +69,9 @@ let rec parser_for_type schema loc type_ref =
     | Some ty ->
       function_name_string ty |> ident_from_string (conv_loc loc)
 
+let filter_out_null_values =
+  [%expr Js.Array.filter (fun (_, value) -> value <> Js.Json.null)]
+
 let json_of_fields schema loc expr fields =
   let field_array_exprs = fields |> List.map
                             (fun {am_name; am_arg_type; _} ->
@@ -79,8 +82,11 @@ let json_of_fields schema loc expr fields =
                                  [%e parser] ([%e expr] ## [%e ident_from_string (conv_loc loc) am_name])
                                )] [@metaloc conv_loc loc]) in
   let field_array = Ast_helper.Exp.array field_array_exprs in
-  [%expr Js.Json.object_ (Js.Dict.fromArray [%e field_array])] [@metaloc conv_loc loc]
-
+  [%expr Js.Json.object_ (
+    [%e field_array]
+    |> [%e filter_out_null_values]
+    |> Js.Dict.fromArray
+    )] [@metaloc conv_loc loc]
 let generate_encoder config (spanning, x) =
   let loc = config.map_loc spanning.span in
   let body = match x with

src/bucklescript/output_bucklescript_unifier.ml

@@ -69,7 +69,11 @@ let make_make_fun config variable_defs =
           |> Ast_helper.Exp.array in 
       let loc = config.map_loc span |> conv_loc in
       let variable_ctor_body = 
-        [%expr Js.Json.object_ (Js.Dict.fromArray [%e make_var_ctor item])] [@metaloc loc]
+        [%expr Js.Json.object_ (
+          [%e make_var_ctor item]
+          |> [%e Output_bucklescript_encoder.filter_out_null_values]
+          |> Js.Dict.fromArray
+          )] [@metaloc loc]
       in
       (
         make_labelled_function item (make_make_triple loc variable_ctor_body),

tests_bucklescript/__tests__/listsArgs.re

@@ -27,8 +27,6 @@ Jest.(describe("Lists as query arguments", () => {
       ())##variables)
     == Js.Json.parseExn({|
       {
-        "nullableOfNullable": null,
-        "nullableOfNonNullable": null,
         "nonNullableOfNullable": [],
         "nonNullableOfNonNullable": []
       }
@@ -43,7 +41,6 @@ Jest.(describe("Lists as query arguments", () => {
     == Js.Json.parseExn({|
       {
         "nullableOfNullable": ["x", null, "y"],
-        "nullableOfNonNullable": null,
         "nonNullableOfNullable": ["a", null, "b"],
         "nonNullableOfNonNullable": ["1", "2", "3"]
       }

tests_bucklescript/__tests__/listsInput.re

@@ -21,7 +21,6 @@ Jest.(describe("Lists as query arguments through input object", () => {
       {
         "arg": {
           "nullableOfNullable": ["x", null, "y"],
-          "nullableOfNonNullable": null,
           "nonNullableOfNullable": ["a", null, "b"],
           "nonNullableOfNonNullable": ["1", "2", "3"]
         }

tests_bucklescript/__tests__/mutationWithOptionalArgument.re

@@ -0,0 +1,19 @@
+module MyMutation = [%graphql {|
+  mutation($field: String) {
+    mutationWithOptionalArgument(field: $field) {
+      value {
+        stringField
+      }
+    }
+  }
+|}];
+
+Jest.(describe("Mutation", () => {
+  open Expect;
+  open! Expect.Operators;
+
+  test("Omits not provided optional arguments", () => {
+    let variables = MyMutation.make(())##variables;
+    expect(variables) == Js.Json.parseExn({|{}|});
+  });
+}));

tests_bucklescript/__tests__/mutationWithOptionalArgument.rei

@@ -0,0 +1,13 @@
+module MyMutation: {
+  type t = Js.t({
+    .
+    mutationWithOptionalArgument: Js.t({ .
+      value: option(Js.t({. stringField: string})),
+    }),
+  });
+
+  let make: (~field: string=?, unit) => Js.t({ . parse: Js.Json.t => t, query: string, variables: Js.Json.t });
+  let makeWithVariables: {. "field": option(string) } => Js.t({ . parse: Js.Json.t => t, query: string, variables: Js.Json.t });
+
+  let query: string;
+};

tests_bucklescript/__tests__/recursiveInput.re

@@ -23,10 +23,8 @@ Jest.(describe("Recursive input types", () => {
       == Js.Json.parseExn({| {
         "arg": {
           "otherField": "test",
-          "enum": null,
           "inner": {
             "otherField": "inner",
-            "inner": null,
             "enum": "SECOND"
           }
         }

tests_bucklescript/__tests__/scalarsArgs.re

@@ -39,15 +39,10 @@ Jest.(describe("Scalars as arguments", () => {
       ~id="an ID",
       ())##variables)
       == Js.Json.parseExn({| {
-        "nullableString": null,
         "string": "a string",
-        "nullableInt": null,
         "int": 123,
-        "nullableFloat": null,
         "float": 1234.5,
-        "nullableBoolean": null,
         "boolean": true,
-        "nullableID": null,
         "id": "an ID"
       } |}));