我正在将Angular Material v6.0 MatTreeModule（mat-tree）与复选框一起使用。
但是我很难弄清楚如何确定哪些节点已被检查以及哪些节点未被检查。
在Angular Material的示例中，他们提供了很好的源代码来进行设置，而我能够很好地进行设置。
但是，我无法确定哪些复选框已选中，哪些复选框未选中。我已经尝试了好几个小时，试图解决这个问题。
我的目标是最终用户将选中或取消选中树中的复选框，然后从那里进行选择后，我需要运行一些过程。
但是我完全想弄清楚哪个mat-tree-nodes是选中的，而没有选中的，在任何地方都找不到很好的工作示例。
找到关键的源代码here
有关垫树的更多信息，请参见here
任何人都可以帮助您确定是否已选中复选框吗？
谢谢。
每个请求，我在这里从两个代码文件中添加代码：
app / tree-checklist-example.ts app / tree-checklist-example.html
来自“ app / tree-checklist-example.ts”的打字稿源代码
import {SelectionModel} from '@angular/cdk/collections';
import {FlatTreeControl} from '@angular/cdk/tree';
import {Component, Injectable} from '@angular/core';
import {MatTreeFlatDataSource, MatTreeFlattener} from '@angular/material/tree';
import {BehaviorSubject} from 'rxjs';
/**
* Node for to-do item
*/
export class TodoItemNode {
children: TodoItemNode[];
item: string;
}
/** Flat to-do item node with expandable and level information */
export class TodoItemFlatNode {
item: string;
level: number;
expandable: boolean;
}
/**
* The Json object for to-do list data.
*/
const TREE_DATA = {
Groceries: {
'Almond Meal flour': null,
'Organic eggs': null,
'Protein Powder': null,
Fruits: {
Apple: null,
Berries: ['Blueberry', 'Raspberry'],
Orange: null
}
},
Reminders: [
'Cook dinner',
'Read the Material Design spec',
'Upgrade Application to Angular'
]
};
/**
* Checklist database, it can build a tree structured Json object.
* Each node in Json object represents a to-do item or a category.
* If a node is a category, it has children items and new items can be added under the category.
*/
@Injectable()
export class ChecklistDatabase {
dataChange = new BehaviorSubject<TodoItemNode[]>([]);
get data(): TodoItemNode[] { return this.dataChange.value; }
constructor() {
this.initialize();
}
initialize() {
// Build the tree nodes from Json object. The result is a list of `TodoItemNode` with nested
// file node as children.
const data = this.buildFileTree(TREE_DATA, 0);
// Notify the change.
this.dataChange.next(data);
}
/**
* Build the file structure tree. The `value` is the Json object, or a sub-tree of a Json object.
* The return value is the list of `TodoItemNode`.
*/
buildFileTree(obj: object, level: number): TodoItemNode[] {
return Object.keys(obj).reduce<TodoItemNode[]>((accumulator, key) => {
const value = obj[key];
const node = new TodoItemNode();
node.item = key;
if (value != null) {
if (typeof value === 'object') {
node.children = this.buildFileTree(value, level + 1);
} else {
node.item = value;
}
}
return accumulator.concat(node);
}, []);
}
/** Add an item to to-do list */
insertItem(parent: TodoItemNode, name: string) {
if (parent.children) {
parent.children.push({item: name} as TodoItemNode);
this.dataChange.next(this.data);
}
}
updateItem(node: TodoItemNode, name: string) {
node.item = name;
this.dataChange.next(this.data);
}
}
/**
* @title Tree with checkboxes
*/
@Component({
selector: 'tree-checklist-example',
templateUrl: 'tree-checklist-example.html',
styleUrls: ['tree-checklist-example.css'],
providers: [ChecklistDatabase]
})
export class TreeChecklistExample {
/** Map from flat node to nested node. This helps us finding the nested node to be modified */
flatNodeMap = new Map<TodoItemFlatNode, TodoItemNode>();
/** Map from nested node to flattened node. This helps us to keep the same object for selection */
nestedNodeMap = new Map<TodoItemNode, TodoItemFlatNode>();
/** A selected parent node to be inserted */
selectedParent: TodoItemFlatNode | null = null;
/** The new item's name */
newItemName = '';
treeControl: FlatTreeControl<TodoItemFlatNode>;
treeFlattener: MatTreeFlattener<TodoItemNode, TodoItemFlatNode>;
dataSource: MatTreeFlatDataSource<TodoItemNode, TodoItemFlatNode>;
/** The selection for checklist */
checklistSelection = new SelectionModel<TodoItemFlatNode>(true /* multiple */);
constructor(private database: ChecklistDatabase) {
this.treeFlattener = new MatTreeFlattener(this.transformer, this.getLevel,
this.isExpandable, this.getChildren);
this.treeControl = new FlatTreeControl<TodoItemFlatNode>(this.getLevel, this.isExpandable);
this.dataSource = new MatTreeFlatDataSource(this.treeControl, this.treeFlattener);
database.dataChange.subscribe(data => {
this.dataSource.data = data;
});
}
getLevel = (node: TodoItemFlatNode) => node.level;
isExpandable = (node: TodoItemFlatNode) => node.expandable;
getChildren = (node: TodoItemNode): TodoItemNode[] => node.children;
hasChild = (_: number, _nodeData: TodoItemFlatNode) => _nodeData.expandable;
hasNoContent = (_: number, _nodeData: TodoItemFlatNode) => _nodeData.item === '';
/**
* Transformer to convert nested node to flat node. Record the nodes in maps for later use.
*/
transformer = (node: TodoItemNode, level: number) => {
const existingNode = this.nestedNodeMap.get(node);
const flatNode = existingNode && existingNode.item === node.item
? existingNode
: new TodoItemFlatNode();
flatNode.item = node.item;
flatNode.level = level;
flatNode.expandable = !!node.children;
this.flatNodeMap.set(flatNode, node);
this.nestedNodeMap.set(node, flatNode);
return flatNode;
}
/** Whether all the descendants of the node are selected */
descendantsAllSelected(node: TodoItemFlatNode): boolean {
const descendants = this.treeControl.getDescendants(node);
return descendants.every(child => this.checklistSelection.isSelected(child));
}
/** Whether part of the descendants are selected */
descendantsPartiallySelected(node: TodoItemFlatNode): boolean {
const descendants = this.treeControl.getDescendants(node);
const result = descendants.some(child => this.checklistSelection.isSelected(child));
return result && !this.descendantsAllSelected(node);
}
/** Toggle the to-do item selection. Select/deselect all the descendants node */
todoItemSelectionToggle(node: TodoItemFlatNode): void {
this.checklistSelection.toggle(node);
const descendants = this.treeControl.getDescendants(node);
this.checklistSelection.isSelected(node)
? this.checklistSelection.select(...descendants)
: this.checklistSelection.deselect(...descendants);
}
/** Select the category so we can insert the new item. */
addNewItem(node: TodoItemFlatNode) {
const parentNode = this.flatNodeMap.get(node);
this.database.insertItem(parentNode!, '');
this.treeControl.expand(node);
}
/** Save the node to database */
saveNode(node: TodoItemFlatNode, itemValue: string) {
const nestedNode = this.flatNodeMap.get(node);
this.database.updateItem(nestedNode!, itemValue);
}
}
HTML source code from "app/tree-checklist-example.html":
<mat-tree [dataSource]="dataSource" [treeControl]="treeControl">
<mat-tree-node *matTreeNodeDef="let node" matTreeNodeToggle matTreeNodePadding>
<button mat-icon-button disabled></button>
<mat-checkbox class="checklist-leaf-node"
[checked]="checklistSelection.isSelected(node)"
(change)="checklistSelection.toggle(node);">{{node.item}}</mat-checkbox>
</mat-tree-node>
<mat-tree-node *matTreeNodeDef="let node; when: hasNoContent" matTreeNodePadding>
<button mat-icon-button disabled></button>
<mat-form-field>
<input matInput #itemValue placeholder="New item...">
</mat-form-field>
<button mat-button (click)="saveNode(node, itemValue.value)">Save</button>
</mat-tree-node>
<mat-tree-node *matTreeNodeDef="let node; when: hasChild" matTreeNodePadding>
<button mat-icon-button matTreeNodeToggle
[attr.aria-label]="'toggle ' + node.filename">
<mat-icon class="mat-icon-rtl-mirror">
{{treeControl.isExpanded(node) ? 'expand_more' : 'chevron_right'}}
</mat-icon>
</button>
<mat-checkbox [checked]="descendantsAllSelected(node)"
[indeterminate]="descendantsPartiallySelected(node)"
(change)="todoItemSelectionToggle(node)">{{node.item}}</mat-checkbox>
<button mat-icon-button (click)="addNewItem(node)"><mat-icon>add</mat-icon></button>
</mat-tree-node>
</mat-tree>
如前所述，要查看完整的源代码及其演示，请转到： https://stackblitz.com/angular/gabkadkvybq?file=app%2Ftree-checklist-example.html
谢谢。
答案 0 :(得分：0)
尚不完全是一个答案（我还没有答案），但是由于我也遇到同样的问题，而且atm没有足够的声誉来添加评论，因此我将在此处发布（mods，如果这是违反规则的。）
在我看来，垫树式越野车是越野车。已经在这里讨论了它：https://github.com/angular/material2/issues/11400，但是在取消/检查子节点/父节点时，那里提供的解决方案仍然不能解决奇怪的行为。这可能会转换为您将从jpavel提到的SelectionModel中获得的值。由于您正在使用此功能，因此请注意。
答案 1 :(得分：0)
您提到的示例使用了Angular材质选择模型。
当属性= SelectionModel且模型类型= TodoItemFlatNode时。 你可以通过->
/** The selection for checklist */
checklistSelection = new SelectionModel<TodoItemFlatNode>(true);
现在将包含checklistSelection属性，您可以访问所有这些方法。
已更改，hasValue，isSelected，选择，onChange，切换等。
因此，现在您可以通过访问上述那些方法来应用选择逻辑。
示例
this.checklistSelection.isSelected ?
答案 2 :(得分：0)
您可以直接从清单选择中获取值
值= this.checklistSelection.selected
这将为您准确返回所有选中项目的值