mdOption 的 (onSelectChange) 输出总是通过列表中的第一项 [英] (onSelectChange) output for mdOption ALWAYS gets passed first item in list

问题描述

我在 Angular 4 (4.3.4) 中使用 Angular Material，我需要挂钩选择事件以清除输入并将对象存储在单独的列表中.但是有一个问题:onSelectChange 输出总是获取第一项作为参数！怎么回事?

这是我的模板:

<md-选项*ngFor="let role of roles | acrole: roleField.value | slice:0:4; let i=index;"[值]="角色"(onSelectionChange)="AddRole(role)" ><div class="label">{{角色.标签}}

</md-option></md-自动完成>

这是我的 AddRole 函数:

AddRole(角色:角色){//角色始终是列表中的第一个角色，无论我单击哪个选项.this.selectedList.push(角色)}

解决方案

通过 onSelectionChange 事件，可以区分项目是被选中还是未选中.您需要将 $event 传递给目标方法以区分这两种情况.

为了使更改生效，您需要进行以下更改:

<块引用>

在您的组件 html 中:

<md-选项*ngFor="let role of roles | acrole: roleField.value | slice:0:4; let i=index;"[值]="角色"(onSelectionChange)="AddRole($event, role)"><div class="label">{{角色.标签}}

</md-option></md-自动完成>

<块引用>

... 并在您的 component.ts 中，将方法更改为以下内容:

AddRole(event: MdOptionSelectionChange, role: Role) {如果(event.source.selected){this.selectedList.push(角色);}}

<小时>

这是一个PLUNKER DEMO材料文档示例.文档需要更清楚地说明这些更改.

I'm using Angular Material for Angular 4 (4.3.4) and I need to hook into the selection event to clear the input and store the object in a separate list. But there's a problem: the onSelectChange output ALWAYS gets the first item as the parameter! What's going on?

Here's my template:

<md-autocomplete [displayWith]="displayRole" #auto="mdAutocomplete">
    <md-option 
        *ngFor="let role of roles | acrole: roleField.value | slice:0:4; let i=index;" 
        [value]="role"
        (onSelectionChange)="AddRole(role)" >
        <div class="label">
          {{role.label}}
        </div>
    </md-option>                    
</md-autocomplete>

And here's my AddRole function:

AddRole(role: Role)
{  
   // role is always the first role in the list, no matter which option I clicked on.
   this.selectedList.push(role) 
}

解决方案

With onSelectionChange event, it is possible to differentiate when the item is selected or unselected. You need to pass an $event to the target method in order to differentiate between the two cases.

Here are the changes you need to make in order to make your changes work:

In your component html:

<md-autocomplete [displayWith]="displayRole" #auto="mdAutocomplete">
    <md-option 
        *ngFor="let role of roles | acrole: roleField.value | slice:0:4; let i=index;" 
        [value]="role" 
        (onSelectionChange)="AddRole($event, role)">

        <div class="label">
            {{role.label}}
        </div>
    </md-option>
</md-autocomplete>

... and in your component.ts, change the method to following:

AddRole(event: MdOptionSelectionChange, role: Role) {  
    if (event.source.selected) {
        this.selectedList.push(role);
    }
}

---

Here is a PLUNKER DEMO based on the Material documentation example. The documentation needs to be a bit more clear about these changes.

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