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in Technique[技术] by (71.8m points)

dart - How to remove a child component with a delete button in the child itself

I have an email component (email-tag.html) that consist of a label, a select and a delete button element.

The email-tag.html component is hosted in its parent email-view-tag.html. email-view-tag contains an add-email-button that adds the email-tag element to the DOM each time it is clicked.

I need help in removing an added email-tag component when its delete-button is clicked. It is the compnoent that contains the delete-button that should be removed.

The two components are shown below:

email-tag.html

 <!DOCTYPE html>

<polymer-element name='email-tag'>
  <template>
   <style>

   .main-flex-container
   {
     display:flex;
     flex-flow:row wrap;
     align-content:flex-start;
   }

    .col
    {
      display:flex;
      flex-flow:column;
      align-content:flex-start;
      flex-grow:1;
    }
   </style>

   <div id='email' class='main-flex-container'>
      <section id='col1' class='col'>
        <input id=emailTxt
               type='text'
               list='_emails'
               value='{{webContact.homeEmail}}'>

        <datalist id='_emails'>
            <template repeat='{{email in emails}}'>
              <option value='{{email}}'>{{email}}</option>
            </template>
        </datalist>
      </section>

      <section id='col2' class='col'>
        <button id='delete-email-btn' type='button' on-click='{{deletePhone}}'>Delete</button>
      </section>
    </div>
   </template>

   <script type="application/dart">

    import 'package:polymer/polymer.dart' show CustomTag, PolymerElement;
    import 'dart:html' show Event, Node;

    @CustomTag( 'email-tag' )
    class EmailElement extends PolymerElement
    {
      //@observable
      EmailElement.created() : super.created();
      List<String> emails = [   '', 'Home', 'Personal', 'Private', 'Work', ];

      void deletePhone( Event e, var detail, Node target)
      {
        //shadowRoot.querySelector('#new-phone' ).remove();
        //print( 'Current row deleted' );
      }
    }
  </script>
</polymer-element>

email-view-tag.html

  <!DOCTYPE html>

  <link rel="import" href="email-tag.html">

  <polymer-element name='email-view-tag'>
    <template>
     <style>

     .main-flex-container
     {
       display:flex;
       flex-flow:row wrap;
       align-content:flex-start;
     }

      .col
      {
        display:flex;
        flex-flow:column;
        align-content:flex-start;
        flex-grow:1;
      }
     </style>

      <div id='email-view' class='main-flex-container'>
        <section id='row0'  >
          <button id='add-email-btn' type='button' on-click='{{addPhone}}'>Add Phone</button>
        </section >

        <section id='rows' class='col'>
       <!--    <epimss-phone-header-tag id='col1' class='col'></epimss-phone-header-tag> -->
          </section>
      </div>
     </template>

     <script type="application/dart">
      import 'package:polymer/polymer.dart' show CustomTag, PolymerElement;
      import 'dart:html' show Event, Node, Element;

      @CustomTag( 'email-view-tag' )
      class EmailViewElement extends PolymerElement
      {
        //@observable
        EmailViewElement.created() : super.created();

        void addPhone( Event e, var detail, Node target )
        {
          $[ 'rows' ].children.add( new Element.tag( 'email-tag' ) );
        }

        @override
        void attached() {
          super.attached();

          $[ 'add-email-btn' ].click();
        }
      }
    </script>
  </polymer-element>

The application does execute normally and clicking the add button does add the email component. The delete button does not work - it is here I am asking for help.

Thanks

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1 Reply

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by (71.8m points)

The child component, <email-tag> should not be in the business of deleting itself. Instead, it should delegate that responsibility to the the parent component, email-view-tag, by dispatching a custom event.

Here is the code for dispatching a custom event from deletePhone:

void deletePhone( Event e, var detail, Node target){
  dispatchEvent(new CustomEvent('notneeded'));
}

Then, in the parent, <custom-view>, change your code for adding <email-tag>s like so:

void addPhone( Event e, var detail, Node target ) {
  $['rows'].children.add( new Element.tag('email-tag'));
  $['rows'].on["notneeded"].listen((Event e) {
    (e.target as Element).remove();
  });
}

Also, I would change the name of deletePhone, since the method no longer deletes the record but merely informs the parent that it is not needed. Call it 'notNeeded' or something similar.


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