问题

我正在尝试使用queryParameters来初始化一个primeNG表格。例如，http://my-url.com/table?name=Joe&first=20 应该显示名为Joe的数据，从第20个条目开始。

该表格使用 `[lazy]=true` 进行懒加载，因为后端提供的数据量非常大。当我初始化我的组件时，我读取URL参数来应用过滤和分页。

my-component.html
```html
<p-table
  [paginator]="true"
  [lazy]="true"
  (onLazyLoad)="onLazyLoad($event)"
  [lazyLoadOnInit]="false"
  [(first)]="firstItem"
> <!-- ... -->

my-component.ts

export class MyComponent {
  @ViewChild('tableElement', {static: true}) pTableRef!: Table;

  protected firstItem = 0;

  ngOnInit(): void {
    this.route?.queryParamMap.pipe(first()).subscribe({
      next: (paramMap) => this.initStateFromParamMap(paramMap)
    });
  }

  ngAfterViewInit(): void {
    console.log("ngAfterViewInit called, this.firstItem = " + this.firstItem)
    // 如果未进行过滤操作，手动使用虚拟参数调用onLazyLoad。
    // 如果进行了过滤操作，p-table会自动调用onLazyLoad
  }

  private initStateFromParamMap(paramMap: ParamMap) {
    // 注意：此代码只是对实际操作的简化
    this.lazyLoadingDoneAtLeastOnce = true;
    this.firstItem = firstItem;
    this.pTableRef.filter("Joe", name, 'equals');
    console.log("init finished, this.firstItem = " + this.firstItem)
  }

  onLazyLoad(event: LazyLoadEvent) {
    console.log("onLazyLoad called, this.firstItem = " + this.firstItem)
    // 从后端加载指定的数据
  }
}

输出：

init finished, this.firstItem = 20
ngAfterViewInit called, this.firstItem = 20
onLazyLoad called, this.firstItem = 0

调用 this.pTableRef.filter("Joe", name, 'equals'); 会导致将 firstItem 设置为零，这是用户决定手动应用过滤时的基本行为。但是，在这种情况下，我不想重置 firstItem。

备注：

• 交换过滤初始化和分页初始化顺序不会改变任何内容。
• 如果未进行过滤操作，ngAfterViewInit 后 this.firstItem 不会更改。
• 为了可读性，省略了我的代码中的许多无关元素。

<details>
<summary>英文:</summary>

I am trying to initialize a primeNG table using queryParameters. e.g. http://my-url.com/table?name=Joe&amp;first=20 should display data with name Joe, beginning at the 20th entry

That table use lazyLoading with `[lazy]=true` because of the sheer amount of data my backend can provides. When I initialize my component I read url parameters to apply filtering and pagination.

my-component.html

<p-table
[paginator]="true"
[lazy]="true"
(onLazyLoad)="onLazyLoad($event)"
[lazyLoadOnInit]="false"
[(first)]="firstItem"
> <!-- ... -->

my-component.ts

export class MyComponent {
@ViewChild('tableElement', {static: true}) pTableRef!: Table;

protected firstItem = 0;

ngOnInit(): void {
this.route?.queryParamMap.pipe(first()).subscribe({
next: (paramMap) => this.initStateFromParamMap(paramMap)
});
}

ngAfterViewInit(): void {
console.log("ngAfterViewInit called, this.firstItem = " + this.firstItem)
// manually call onLazyLoad with dummy parameters if no filtering is done.
// if filtering is done, p-table automatically calls onLazyLoad
}

private initStateFromParamMap(paramMap: ParamMap) {
// note : this code is a just simplification of what is done
this.lazyLoadingDoneAtLeastOnce = true;
this.firstItem = firstItem;
this.pTableRef.filter("Joe", name, 'equals');
console.log("init finished, this.firstItem = " + this.firstItem)
}

onLazyLoad(event: LazyLoadEvent) {
console.log("onLazyLoad called, this.firstItem = " + this.firstItem)
// load specified data from backend
}
}

output:

init finished, this.firstItem = 20
ngAfterViewInit called, this.firstItem = 20
onLazyLoad called, this.firstItem = 0

Calling `this.pTableRef.filter("Joe", name, 'equals');` result in firstItem being set to zero, this is the basic behaviour if the user decides to manually apply a filter. However I do not want to reset the firstItem in this case.

Notes: 
- Swapping filter initialization and pagination initialization order does not change anything.
- If no filtering is done. `this.firstItem` is not changed after `ngAfterViewInit`
- Many unrelated element of my code have been omitted for readability

</details>


# 答案1
**得分**: 0

在查看PrimeNG Table源代码时，我发现了一个名为`restoringFilter`的布尔属性，如果将其设置为true，下一次过滤将不会重置第一项。

顺便说一下，调用`filters`会触发超时过滤，这就是为什么连续进行多次过滤不会触发多次调用`onLazyLoad`的原因，这也是过滤（因此重新初始化第一项为0...）在ngAfterViewInit之后进行的原因。

简而言之，当恢复过滤时，请将`restoringFilter`设置为true

```javascript
this.pTableRef.restoringFilter = true;
this.pTableRef.filter("Joe", name, 'equals');

现在这个功能完美运行。

this.pTableRef.restoringFilter = true;  
this.pTableRef.filter("Joe", name, 'equals');