Fix refetch empty array (#601)

* add failing test that illustrates the problem

* fix

* changelog

* add one more test

Author: zth

CHANGELOG.md

@@ -1,5 +1,7 @@
 # master
 
+- Fix issue with empty arrays and refetch variables. https://github.com/zth/rescript-relay/pull/601
+
 # 4.2.1
 
 - Actually apply fix for lowering the glibc requirement from the PR in 3.5.1, to the release. This was not applied to the actual release until now.

packages/rescript-relay/__tests__/Test_removeUndefinedAndConvertNulls-tests.js

@@ -0,0 +1,40 @@
+const {
+  internal_removeUndefinedAndConvertNullsRaw,
+} = require("../src/RescriptRelay_Internal.bs");
+
+describe("internal_removeUndefinedAndConvertNullsRaw", () => {
+  it("keeps empty arrays while converting Some(None) to null", () => {
+    const input = {
+      after: { BS_PRIVATE_NESTED_SOME_NONE: 0 },
+      forSaleStatuses: [],
+      nullArray: [null],
+      first: 12,
+      omitted: undefined,
+    };
+
+    expect(internal_removeUndefinedAndConvertNullsRaw(input)).toEqual({
+      after: null,
+      forSaleStatuses: [],
+      nullArray: [null],
+      first: 12,
+    });
+  });
+
+  it("drops None values and preserves non-null data", () => {
+    const input = {
+      noneValue: undefined,
+      zero: 0,
+      empty: "",
+      nope: false,
+      obj: { bar: 1 },
+    };
+
+    expect(internal_removeUndefinedAndConvertNullsRaw(input)).toEqual({
+      zero: 0,
+      empty: "",
+      nope: false,
+      obj: { bar: 1 },
+    });
+  });
+
+});

packages/rescript-relay/src/RescriptRelay_Internal.res

@@ -17,12 +17,19 @@ let internal_cleanObjectFromUndefinedRaw = record =>
   | Some(v) => v
   }
 
+let internal_isSomeNone: 'any => bool = %raw(`value => value != null && value.BS_PRIVATE_NESTED_SOME_NONE === 0`)
+
 let internal_removeUndefinedAndConvertNullsRaw = record =>
   internal_keepMapFieldsRaw(record, ((key, value)) => {
-    switch (value, value == Some(None)) {
-    | (_, true) => Some((key, Nullable.null))
-    | (Some(value), _) => Some((key, Nullable.make(value)))
-    | (None, _) => None
+    let rawValue = value
+    switch value {
+    | Some(value) =>
+      if internal_isSomeNone(rawValue) {
+        Some((key, Nullable.null))
+      } else {
+        Some((key, Nullable.make(value)))
+      }
+    | None => None
     }
   })