Merge pull request #14110 from ckeditor/ck/13965

Feature (utils). Add support for optional properties in `ObservableMixin` bind chain. Closes #13965.
ckeditor · May 15, 2023 · 37a44d8 · 37a44d8
2 parents e448b2e + cb03ce8
commit 37a44d8
Showing 1 changed file with 29 additions and 14 deletions.
diff --git a/packages/ckeditor5-utils/src/observablemixin.ts b/packages/ckeditor5-utils/src/observablemixin.ts
@@ -1267,14 +1267,14 @@ interface SingleBindChain<TKey extends string, TVal> {
 		callback: ( ...values: Array<O[ K ]> ) => TVal
 	): void;
 
-	to<O extends Observable & { [ P in TKey ]: TVal }>(
+	to<O extends ObservableWithProperty<TKey, TVal>>(
 		observable: O
 	): void;
-	to<O extends Observable & { [ P in TKey ]: any }>(
+	to<O extends ObservableWithProperty<TKey>>(
 		observable: O,
 		callback: ( value: O[ TKey ] ) => TVal
 	): void;
-	to<O extends Observable & { [ P in K ]: TVal }, K extends keyof O>(
+	to<O extends ObservableWithProperty<K, TVal>, K extends keyof O>(
 		observable: O,
 		key: K
 	): void;
@@ -1284,8 +1284,8 @@ interface SingleBindChain<TKey extends string, TVal> {
 		callback: ( value: O[ K ] ) => TVal,
 	): void;
 	to<
-		O1 extends Observable & { [ P in TKey ]: any },
-		O2 extends Observable & { [ P in TKey ]: any }
+		O1 extends ObservableWithProperty<TKey>,
+		O2 extends ObservableWithProperty<TKey>
 	>(
 		observable1: O1,
 		observable2: O2,
@@ -1304,9 +1304,9 @@ interface SingleBindChain<TKey extends string, TVal> {
 		callback: ( value1: O1[ K1 ], value2: O2[ K2 ] ) => TVal
 	): void;
 	to<
-		O1 extends Observable & { [ P in TKey ]: any },
-		O2 extends Observable & { [ P in TKey ]: any },
-		O3 extends Observable & { [ P in TKey ]: any }
+		O1 extends ObservableWithProperty<TKey>,
+		O2 extends ObservableWithProperty<TKey>,
+		O3 extends ObservableWithProperty<TKey>
 	>(
 		observable1: O1,
 		observable2: O2,
@@ -1330,10 +1330,10 @@ interface SingleBindChain<TKey extends string, TVal> {
 		callback: ( value1: O1[ K1 ], value2: O2[ K2 ], value3: O3[ K3 ] ) => TVal
 	): void;
 	to<
-		O1 extends Observable & { [ P in TKey ]: any },
-		O2 extends Observable & { [ P in TKey ]: any },
-		O3 extends Observable & { [ P in TKey ]: any },
-		O4 extends Observable & { [ P in TKey ]: any }
+		O1 extends ObservableWithProperty<TKey>,
+		O2 extends ObservableWithProperty<TKey>,
+		O3 extends ObservableWithProperty<TKey>,
+		O4 extends ObservableWithProperty<TKey>
 	>(
 		observable1: O1,
 		observable2: O2,
@@ -1363,9 +1363,24 @@ interface SingleBindChain<TKey extends string, TVal> {
 	): void;
 }
 
+/**
+ * A helper type that can be used as a constraint, ensuring the type is both observable and have the given property.
+ *
+ * ```ts
+ * // Ensures that `obj` is `Observable` and have property named 'abc'.
+ * function f<O extends ObservableWithProperty<'abc'>>( obj: O ) {}
+ *
+ * // Ensures that `obj` is `Observable` and have property named 'abc' with value `number`.
+ * function f<O extends ObservableWithProperty<'abc', number>>( obj: O ) {}
+ * ```
+ */
+export type ObservableWithProperty<TKey extends PropertyKey, TVal = any> = undefined extends TVal ?
+	Observable & { [ P in TKey ]?: TVal } :
+	Observable & { [ P in TKey ]: TVal };
+
 interface DualBindChain<TKey1 extends string, TVal1, TKey2 extends string, TVal2> {
 	to<
-		O extends Observable & { [ P in K1 ]: TVal1 } & { [ P in K2 ]: TVal2 },
+		O extends ObservableWithProperty<K1, TVal1> & ObservableWithProperty<K2, TVal2>,
 		K1 extends keyof O,
 		K2 extends keyof O
 	>(
@@ -1375,7 +1390,7 @@ interface DualBindChain<TKey1 extends string, TVal1, TKey2 extends string, TVal2
 	): void;
 
 	to<
-		O extends Observable & { [ P in TKey1 ]: TVal1 } & { [ P in TKey2 ]: TVal2 }
+		O extends ObservableWithProperty<TKey1, TVal1> & ObservableWithProperty<TKey2, TVal2>
 	>(
 		observable: O
 	): void;