fix: Fixed typings and arguments of mergeQueries()

mnasyrov · Sep 2, 2021 · 156abcc · 156abcc
1 parent c8a5137
commit 156abcc
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Showing 3 changed files with 25 additions and 12 deletions.
diff --git a/packages/rx-effects/README.md b/packages/rx-effects/README.md
@@ -178,7 +178,7 @@ Utility functions:
   const store2 = createStore<number>(3);
   const sumValueQuery = mergeQueries(
     [store1, store2],
-    ([value1, value2]) => value1 + value2,
+    (value1, value2) => value1 + value2,
   );
   ```
 

diff --git a/packages/rx-effects/src/stateQuery.test.ts b/packages/rx-effects/src/stateQuery.test.ts
@@ -26,7 +26,7 @@ describe('mergeQueries()', () => {
   it('should return a calculated value from source queries', () => {
     const store1 = createStore(2);
     const store2 = createStore('text');
-    const query = mergeQueries([store1, store2], ([a, b]) => ({ a, b }));
+    const query = mergeQueries([store1, store2], (a, b) => ({ a, b }));
 
     expect(query.get()).toEqual({ a: 2, b: 'text' });
 
@@ -40,7 +40,7 @@ describe('mergeQueries()', () => {
   it('should return an observable with the calculated value from source queries', async () => {
     const store1 = createStore(2);
     const store2 = createStore('text');
-    const query = mergeQueries([store1, store2], ([a, b]) => ({ a, b }));
+    const query = mergeQueries([store1, store2], (a, b) => ({ a, b }));
 
     expect(await firstValueFrom(query.value$)).toEqual({ a: 2, b: 'text' });
 
@@ -50,4 +50,16 @@ describe('mergeQueries()', () => {
     store2.set('text2');
     expect(await firstValueFrom(query.value$)).toEqual({ a: 3, b: 'text2' });
   });
+
+  it('should infer types for values of the queries', () => {
+    const store1 = createStore<number>(2);
+    const store2 = createStore<{ value: number }>({ value: 3 });
+
+    const query: StateQuery<number> = mergeQueries(
+      [store1, store2],
+      (value, obj) => value + obj.value,
+    );
+
+    expect(query.get()).toEqual(5);
+  });
 });
diff --git a/packages/rx-effects/src/stateQuery.ts b/packages/rx-effects/src/stateQuery.ts
@@ -36,19 +36,20 @@ export function mapQuery<T, R>(
  * @param queries source queries
  * @param merger value merger
  */
-export function mergeQueries<
-  Queries extends StateQuery<unknown>[],
-  Values extends {
-    [K in keyof Queries]: Queries[K] extends StateQuery<infer V> ? V : never;
-  },
-  Result,
->(queries: Queries, merger: (values: Values) => Result): StateQuery<Result> {
+export function mergeQueries<Values extends unknown[], Result>(
+  queries: [
+    ...{
+      [K in keyof Values]: StateQuery<Values[K]>;
+    }
+  ],
+  merger: (...values: Values) => Result,
+): StateQuery<Result> {
   const value$ = combineLatest(queries.map((query) => query.value$)).pipe(
-    map((values) => merger(values as Values)),
+    map((values) => merger(...(values as Values))),
   );
 
   return {
-    get: () => merger(queries.map((query) => query.get()) as Values),
+    get: () => merger(...(queries.map((query) => query.get()) as Values)),
     value$,
   };
 }