How to use Angular2 templates with *ngFor to create a table out of nested arrays?

问题

Given the following array in component property groups:

[
   {
     "name": "pencils",
     "items": ["red pencil","blue pencil","yellow pencil"]
   },
   {
     "name": "rubbers",
     "items": ["big rubber","small rubber"]
   },
]

How to create a html table with all items, each in one row? The expected HTML result:

<table>
    <tr><td><h1>pencils</h1></td></tr>
    <tr><td>red pencil</td></tr>
    <tr><td>blue pencil</td></tr>
    <tr><td>yellow pencil</td></tr>
    <tr><td><h1>rubbers</h1></td></tr>
    <tr><td>big rubber</td></tr>
    <tr><td>small rubber</td></tr>
</table>

The first level is easy:

<table>
    <tr *ngFor="#group of groups">
        <td><h1>{{group.name}}</h1></td>
    </tr>
</table>

But now I have to iterate #item of group. The problem is that I need the new <tr> elements after the </tr> element which defines group, not inside.

Is there any solution for this kind of problems in Angular2 templating? I would expect some special tag which I could use instead of <tr> which is not written into the dom. Something similar to facets and fragments in JSF.

回答1:

<table>
     <ng-container *ngFor="let group of groups">
         <tr><td><h2>{{group.name}}</h2></td></tr>
         <tr *ngFor="let item of group.items"><td>{{item}}</td></tr>
     </ng-container>
</table>

回答2:

You can use the template syntax of ngFor on groups and the usual syntax inside it for the actual rows like:

<table>
  <template let-group ngFor [ngForOf]="groups">
    <tr *ngFor="let row of group.items">{{row}}</tr>
  </template>
</table>

Check this plunk

回答3:

Here is a basic approach - it sure can be improved - of what I understood to be your requirement.

This will display 2 columns, one with the groups name, and one with the list of items associated to the group.

The trick is simply to include a list within the items cell.

<table>
  <thead>
    <th>Groups Name</th>
    <th>Groups Items</th>
  </thead>
  <tbody>
    <tr *ngFor="let group of groups">
      <td>{{group.name}}</td>
      <td>
        <ul>
          <li *ngFor="let item of group.items">{{item}}</li>
        </ul>
      </td>
    </tr>
  </tbody>
</table>

回答4:

it's not exact output that you wanted but maybe something like this will do. Parent cmp:

<table>
  <item *ngFor="#i of items" [data]="i"></item>
</table>

Child cmp

import {Component} from 'angular2/core';

@Component({
  selector: `item`,
  inputs: ['data'],
  template: `
    <tr><td>{{data.name}}</td></tr>
    <tr *ngFor="#i of data.items">
      <td><h1>{{i}}</h1></td>
    </tr>
  `
})
export default class Item {


}

回答5:

Try this. The scope of local variables defined by "template" directive.

<table>
  <template ngFor let-group="$implicit" [ngForOf]="groups">
    <tr>
      <td>
        <h2>{{group.name}}</h2>
      </td>
    </tr>
    <tr *ngFor="let item of group.items">
                <td>{{item}}</td>
            </tr>
  </template>
</table>

回答6:

I am a fan of keeping logic out of the template as much as possible. I would suggest creating a helper function that returns the data that you care about to the template. For instance:

getItemsForDisplay():String[] {
 return [].concat.apply([],this.groups.map(group => group.items));
};

<tr *ngFor="let item of getItemsForDisplay()"><td>{{item}}</td></tr>

This will let you keep your presentation free of special logic. This also lets you use your datasource "directly".

回答7:

This worked for me.

<table>
  <tr>
    <td *ngFor="#group of groups">
       <h1>{{group.name}}</h1>
   </td>
  </tr>
</table>

来源：https://stackoverflow.com/questions/35699962/how-to-use-angular2-templates-with-ngfor-to-create-a-table-out-of-nested-arrays

标签

angular

angular2-template

angular-template