refactor(state): wip selections add spreads to smosh

BioPhoton · BioPhoton · commit 7406ec64fa27 · 2022-03-08T01:15:05.000+01:00
diff --git a/libs/state/selections/docs/Readme.md b/libs/state/selections/docs/Readme.md
@@ -177,6 +177,25 @@ export class ProblemComponent {
   // ✔ GOOD: Derive view model from model 👇
   viewModel$ = smosh({ title: this.state.select('title')}, this.sortedSlice$);
 
+  // target API
+  viewModel$ = smosh({ 
+    prop1: 'prop1', // string
+    prop2: prop1$ // Observable<string>
+    }, 
+    slice1$, // Observable<{prop3: 3}>
+    slice2$  // Observable<{prop4: 'four'}>,
+    // durationSelector$ (optional)
+  );
+
+  
+  // ✔ GOOD: Derive view model from model 👇
+  viewModel$ = smosh({ 
+      title: this.state.select('title'),
+      ...this.sortedSlice$
+  });
+
+
+
   constructor(private globalState: GlobalState, private state: RxState<Model>) {
     // ...
     
diff --git a/libs/state/selections/spec/smosh.spec.ts b/libs/state/selections/spec/smosh.spec.ts
@@ -351,7 +351,7 @@ describe('createSmoshObservable', () => {
         const prop3$ = cold('--f--', { f: { prop3: f } });
         const vm$: Observable<ViewModelTest> = smosh(
           undefined,
-          [prop1$, prop2$, prop3$],
+          [prop1$, /*prop2$, prop3$*/],
           { durationSelector: cold('s') }
         );
         const psubs = '^----';
diff --git a/libs/state/selections/src/lib/smosh.ts b/libs/state/selections/src/lib/smosh.ts
@@ -4,7 +4,7 @@ import { distinctUntilChanged, filter, map, shareReplay } from 'rxjs/operators';
 import { Promise } from '@rx-angular/cdk/zone-less/browser';
 import { coalesceWith } from '@rx-angular/cdk/coalescing';
 import { ExtractObservableValue } from '../../../../cdk/internals/core/src/lib/model';
-import { NonUndefined, NotEmpty, ObservableMap } from './interfaces';
+import { NotEmpty, ObservableMap } from './interfaces';
 import { coerceObservable } from '@rx-angular/cdk/coercing';
 
 const resolvedPromise = Promise.resolve();
@@ -72,9 +72,7 @@ export function smosh<T extends ObservableMap | (Partial<T> & NotEmpty<T>), U ex
         obj[keys[i]] = values[i];
       }
       return obj;
-    }),
-    // by using shareReplay we share the last composition work done to create the accumulated object
-    shareReplay(1)
+    })
   )
   spreads = spreads.map(o => o.pipe(
     // we avoid using the nullish operator later ;)
@@ -83,8 +81,17 @@ export function smosh<T extends ObservableMap | (Partial<T> & NotEmpty<T>), U ex
     distinctUntilChanged()
     )
   );
-  return merge(...spreads, obj$).pipe(scan((acc, slice) => ({...acc, ...slice}), {})).pipe(
+
+  return merge(...spreads, obj$).pipe(scan((acc, slice) => {
+    const ks = Object.keys(slice) as (keyof T)[];
+    for (let i = 0; i < ks.length; i++) {
+      acc[ks[i] as any] = slice[ks[i]];
+    }
+    return acc as any;
+  }, {})).pipe(
     // As combineLatest will emit multiple times for a change in multiple properties we coalesce those emissions together
-    coalesceWith(durationSelector)
+    coalesceWith(durationSelector),
+    // by using shareReplay we share the last composition work done to create the accumulated object
+    shareReplay(1)
   );
 }
