Return null when input is null

izumin5210 · Sep 13, 2021 · 97ade9f · 97ade9f
1 parent de7703a
commit 97ade9f
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Showing 2 changed files with 12 additions and 2 deletions.
diff --git a/src/maskWithFragment.test.ts b/src/maskWithFragment.test.ts
@@ -8,6 +8,12 @@ import * as multipleFragmentsFixtures from "./__fixtures__/graphql/__generated__
 import * as rootListFixtures from "./__fixtures__/graphql/__generated__/rootList.generated";
 import * as unionFixtures from "./__fixtures__/graphql/__generated__/union.generated";
 
+it("returns null when 2nd arg is null", () => {
+  const output = maskWithFragment(simpleFixtures.UserHeaderFragmentDoc, null);
+  expectType<null>(output);
+  expect(output).toBeNull();
+});
+
 it("masks query results with simple fragment", () => {
   const input: simpleFixtures.GetUserHeaderQuery = {
     __typename: "Query",

diff --git a/src/maskWithFragment.ts b/src/maskWithFragment.ts
@@ -82,13 +82,17 @@ export function maskWithFragment<
   TFilteredData extends Record<string, unknown>,
   TData extends TFilteredData = TFilteredData
 >(doc: DocumentNode | TypedDocumentNode<TFilteredData, any>, input: ReadonlyArray<TData>): ReadonlyArray<TFilteredData>;
+export function maskWithFragment(doc: DocumentNode | TypedDocumentNode<any, any>, input: null): null;
+export function maskWithFragment(doc: DocumentNode | TypedDocumentNode<any, any>, input: undefined): undefined;
 export function maskWithFragment<
   TFilteredData extends Record<string, unknown>,
   TData extends TFilteredData = TFilteredData
 >(
   doc: DocumentNode | TypedDocumentNode<TFilteredData, any>,
-  input: TData | ReadonlyArray<TData>
-): TFilteredData | ReadonlyArray<TFilteredData> {
+  input: TData | ReadonlyArray<TData> | null | undefined
+): TFilteredData | ReadonlyArray<TFilteredData> | null | undefined {
+  if (input == null) return input;
+
   if (doc.definitions[0]?.kind !== "FragmentDefinition") {
     throw new Error("input document should be fragment definition");
   }