Expose itemIdGenerator that can be used to generate unique ID for items on ListView (NativeScript#4964)

buuhuu · Hristo Hristov · commit 4bcb9840c1eb · 2017-12-05T11:53:32.000+02:00
* fixed the context of the getItem() call in android's ListView adapter (NativeScript#4962) * added itemIdGenerator function to the list-view interface to allow delegating the creating of a unique id for an item to a consumer of the listview (NativeScript#4962)
diff --git a/tns-core-modules/ui/list-view/list-view-common.ts b/tns-core-modules/ui/list-view/list-view-common.ts
@@ -23,8 +23,9 @@ export abstract class ListViewBase extends View implements ListViewDefinition {
     public static itemTapEvent = "itemTap";
     public static loadMoreItemsEvent = "loadMoreItems";
     // TODO: get rid of such hacks.
-    public static knownFunctions = ["itemTemplateSelector"]; //See component-builder.ts isKnownFunction
+    public static knownFunctions = ["itemTemplateSelector", "itemIdGenerator"]; //See component-builder.ts isKnownFunction
 
+    private _itemIdGenerator: (item: any, index: number, items: any) => number = (_item: any, index: number) => index;
     private _itemTemplateSelector: (item: any, index: number, items: any) => string;
     private _itemTemplateSelectorBindable = new Label();
     public _defaultTemplate: KeyedTemplate = {
@@ -72,6 +73,14 @@ export abstract class ListViewBase extends View implements ListViewDefinition {
         }
     }
 
+    get itemIdGenerator(): (item: any, index: number, items: any) => number {
+        return this._itemIdGenerator;
+    }
+
+    set itemIdGenerator(generatorFn: (item: any, index: number, items: any) => number) {
+        this._itemIdGenerator = generatorFn;
+    }
+
     public refresh() {
         //
     }
diff --git a/tns-core-modules/ui/list-view/list-view.android.ts b/tns-core-modules/ui/list-view/list-view.android.ts
@@ -216,14 +216,19 @@ function ensureListViewAdapterClass() {
         public getItem(i: number) {
             if (this.owner && this.owner.items && i < this.owner.items.length) {
                 let getItem = (<ItemsSource>this.owner.items).getItem;
-                return getItem ? getItem(i) : this.owner.items[i];
+                return getItem ? getItem.call(this.owner.items, i) : this.owner.items[i];
             }
 
             return null;
         }
 
         public getItemId(i: number) {
-            return long(i);
+            let item = this.getItem(i);
+            let id = i;
+            if (this.owner && item && this.owner.items) {
+                id = this.owner.itemIdGenerator(item, i, this.owner.items);
+            }
+            return long(id);
         }
 
         public hasStableIds(): boolean {
diff --git a/tns-core-modules/ui/list-view/list-view.d.ts b/tns-core-modules/ui/list-view/list-view.d.ts
@@ -63,6 +63,11 @@ export class ListView extends View {
      */
     itemTemplateSelector: string | ((item: any, index: number, items: any) => string);
 
+    /**
+     * Item id generator
+     */
+    itemIdGenerator: (item: any, index: number, items: any) => number;
+
     /**
      * Gets or set the items separator line color of the ListView. 
      */

Original file line number	Diff line number	Diff line change
`@@ -216,14 +216,19 @@ function ensureListViewAdapterClass() {`
`216`	`216`	`public getItem(i: number) {`
`217`	`217`	`if (this.owner && this.owner.items && i < this.owner.items.length) {`
`218`	`218`	`let getItem = (<ItemsSource>this.owner.items).getItem;`
`219`		`- return getItem ? getItem(i) : this.owner.items[i];`
	`219`	`+ return getItem ? getItem.call(this.owner.items, i) : this.owner.items[i];`
`220`	`220`	`}`
`221`	`221`
`222`	`222`	`return null;`
`223`	`223`	`}`
`224`	`224`
`225`	`225`	`public getItemId(i: number) {`
`226`		`- return long(i);`
	`226`	`+ let item = this.getItem(i);`
	`227`	`+ let id = i;`
	`228`	`+ if (this.owner && item && this.owner.items) {`
	`229`	`+ id = this.owner.itemIdGenerator(item, i, this.owner.items);`
	`230`	`+ }`
	`231`	`+ return long(id);`
`227`	`232`	`}`
`228`	`233`
`229`	`234`	`public hasStableIds(): boolean {`