fix(module:tree): nzCheckBoxChange never emitting (#8038)

components/core/tree/nz-tree-base.service.ts

@@ -55,6 +55,26 @@ export class NzTreeBaseService {
     return this.conductNodeState('select');
   }
 
+  /**
+   * get checked node keys
+   */
+  getCheckedNodeKeys(): NzTreeNodeKey[] {
+    const keys: NzTreeNodeKey[] = [];
+    const checkedNodes = this.getCheckedNodeList();
+
+    const calc = (nodes: NzTreeNode[]): void => {
+      nodes.forEach(node => {
+        keys.push(node.key);
+        if (node.children.length < 1) return;
+        calc(node.children);
+      });
+    };
+
+    calc(checkedNodes);
+
+    return keys;
+  }
+
   /**
    * return checked nodes
    */

components/tree/tree.component.ts

@@ -224,7 +224,7 @@ export class NzTreeComponent
 
   @Output() readonly nzExpandedKeysChange: EventEmitter<string[]> = new EventEmitter<string[]>();
   @Output() readonly nzSelectedKeysChange: EventEmitter<string[]> = new EventEmitter<string[]>();
-  @Output() readonly nzCheckedKeysChange: EventEmitter<string[]> = new EventEmitter<string[]>();
+  @Output() readonly nzCheckedKeysChange: EventEmitter<NzTreeNodeKey[]> = new EventEmitter<NzTreeNodeKey[]>();
   @Output() readonly nzSearchValueChange = new EventEmitter<NzFormatEmitEvent>();
   @Output() readonly nzClick = new EventEmitter<NzFormatEmitEvent>();
   @Output() readonly nzDblClick = new EventEmitter<NzFormatEmitEvent>();
@@ -426,6 +426,8 @@ export class NzTreeComponent
         // Cause check method will rerender list, so we need recover it and next the new event to user
         const eventNext = this.nzTreeService.formatEvent('check', node, event.event!);
         this.nzCheckBoxChange.emit(eventNext);
+        const checkedKeys = this.nzTreeService.getCheckedNodeKeys();
+        this.nzCheckedKeysChange.emit(checkedKeys);
         break;
       case 'dragstart':
         // if node is expanded