ngModel for textarea not working in angular 2

Question

I am trying to print json object in textarea using ngModel.

I have done following:

</script>
<ins class="adsbygoogle"
     style="display:block"
     data-ad-client="ca-pub-5408099190056760"
     data-ad-slot="7305827575"
     data-ad-format="auto"
     data-full-width-responsive="true"></ins>
<script>
     (adsbygoogle = window.adsbygoogle || []).push({});
</script>        </div>
                      <div class="relativetags">
              相关标签:
       </div>
      </div>
      
      <div class="fly-panel detail-box" id="flyReply">
        <fieldset class="layui-elem-field layui-field-title" style="text-align: center;">
          <legend>8条回答</legend>        </fieldset>

        <ul class="jieda" id="jieda">
                         				            <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-67.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000067.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-67.html" class="fly-link">
                  <cite>天命终不由人 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:21</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       
<p>For binding textarea values in Angular 2 you can use the change-function:</p>

<h1>Template</h1>

<pre><code><textarea id="some-value" (change)="doTextareaValueChange($event)">{{textareaValue}}</textarea>
</code></pre>

<h1>Component</h1>

<pre><code>export class AppComponent implements OnInit {
  private textareaValue = '';
  doTextareaValueChange(ev) {
    try {
      this.textareaValue = ev.target.value;
    } catch(e) {
      console.info('could not set textarea-value');
    }
  }
}
</code></pre>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115044'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115044">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115044">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115044">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-87.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000087.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-87.html" class="fly-link">
                  <cite>名媛妹妹 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:21</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       
<p>Unless you really want to have sync in between, you would normally implement a button to save/apply the change when it's finished json editing. If that is the case, your render is easy.</p>

<pre><code><textarea #textbox>{{ rapidPage | json }}</textarea>
</code></pre>

<p>Make sure no other space or return character in between the above line.</p>

<p>Then an traditional button, ex. </p>

<pre><code><a (click)="updateRapidPage(textbox.value)">Apply</a>
</code></pre>

<p>I found this is better in some case than brutal <code>[(rapidPage)]</code>.</p>

<p>You can also use <code>@ViewChild('textbox') input</code> inside the component to access this variable.</p>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115045'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115045">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115045">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115045">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-99.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000099.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-99.html" class="fly-link">
                  <cite>忘掉有多难 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:25</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       
<pre class="lang-html prettyprint-override"><code><textarea class="form-control" 
          name="message"
          rows="8"
          [(ngModel)]="Obj.message"
          #message='ngModel'
          ></textarea>
</code></pre>

<p>for Two way binding You just need to add attribute in textarea tag <code>name="message"</code>,  ONLY <code>[(ngModel)]</code> works 100%!.</p>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115043'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115043">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115043">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115043">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-78.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000078.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-78.html" class="fly-link">
                  <cite>鱼传尺愫 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:27</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       
<p>As per documentation [()] is for two way syntax sugar to remove the boilerplate. What event is being invoked at this? Irrespective, you can put a string output also alongwith the event in below code</p>

<p>Probably try the below code implemetation for your string output</p>

<pre><code>@Directive({
  selector: '[ngModel]',
  host: {
    "[value]": 'ngModel',
    "(input)": "ngModelChange.next($event.target.value)"
  }
})
class NgModelDirective {
  @Input() ngModel:any; // stored value
  @Output() ngModelChange:EventEmitter; = new EventEmitter() // an event emitter
}
</code></pre>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115048'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115048">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115048">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115048">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-56.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000056.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-56.html" class="fly-link">
                  <cite>遇见更好的自我 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:39</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       


<p>Assuming that you want to bind <code>rapidPage</code> as it is and will only write valid JSON in the textArea.</p>

<ul>
<li>You need to <code>PARSE</code> it when changing the value, and <code>STRINGIFY</code> when showing in textarea.</li>
</ul>

<hr>

<p>StackBlitz DEMO</p>

<p>Do the following in your Component code</p>

<pre class="lang-ts prettyprint-override"><code>  rapidPage = {"pageRows":[{"sections":[{"sectionRows":[{"secRowColumns":[]},{"secRowColumns":[{"colName":"users"}]},{"secRowColumns":[{"colName":"sample"}]}],"width":0}]}],"pageName":"DefaultPage","pageLayout":"DEFAULT_LAYOUT","editMode":true}; 
  // your object

  get rapidPageValue () {
    return JSON.stringify(this.rapidPage, null, 2);
  }

  set rapidPageValue (v) {
    try{
    this.rapidPage = JSON.parse(v);}
    catch(e) {
      console.log('error occored while you were typing the JSON');
    };
  }
</code></pre>

<p>Template Usage: </p>

<pre class="lang-ts prettyprint-override"><code><textarea [(ngModel)]='rapidPageValue' rows="30" cols="120">                             
</textarea>
</code></pre>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115042'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115042">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115042">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115042">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          <li data-id="111">
            <a name="item-1111111111"></a>
           
            <div class="detail-about detail-about-reply">
                              <a class="fly-avatar" href="https://www.e-learn.cn/qa/u-37.html">
                <img src="https://www.e-learn.cn/qa/data/avatar/000/00/00/small_000000037.jpg" alt=" ">
              </a>
              <div class="fly-detail-user">
                <a href="https://www.e-learn.cn/qa/u-37.html" class="fly-link">
                  <cite>借酒劲吻你 </cite>       
                </a>
              </div>
                            <div class="detail-hits">
                <span>2021-02-06 23:39</span>
              </div>
            </div>
            <div class="detail-body jieda-body photos">
                                                                       
<p>ngModel works if</p>

<ol>
<li>There is a form wrapped around it & textarea has a name attribute added to it.</li>
</ol>

<p>If you not you can use the following syntax to achieve the same effect</p>

<pre><code><textarea [value]="strVariableInComponent" (input)="strVariableInComponent = $event.target.value;"></textarea>
</code></pre>
                                                                        <div class="appendcontent">
                                                        </div>
            </div>
            <div class="jieda-reply">
              <span class="jieda-zan button_agree" type="zan" data-id='2115046'>
                <i class="iconfont icon-zan"></i>
                <em>0</em>
              </span>
                 <span type="reply" class="showpinglun" data-id="2115046">
                <i class="iconfont icon-svgmoban53"></i>
               讨论(0)
              </span>
              
                                                   
              <div class="jieda-admin">
                                                            </div>
            </div>
                      <div class="comments-mod "  style="display: none; float:none;padding-top:10px;" id="comment_2115046">
                    <div class="areabox clearfix">

<form class="layui-form" action="">
               
            <div class="layui-form-item">
    <label class="layui-form-label" style="padding-left:0px;width:60px;">发布评论:</label>
    <div class="layui-input-block" style="margin-left:90px;">
         <input type="text" placeholder="不少于5个字" AUTOCOMPLETE="off" class="comment-input layui-input" name="content" />
                        <input type='hidden' value='0' name='replyauthor' />
    </div>
    <div class="mar-t10"><span class="fr layui-btn layui-btn-sm addhuidapinglun" data-id="2115046">提交评论 </span></div>
  </div>
  
</form>
                    </div>
                    <hr>
                    <ul class="my-comments-list nav">
                        <li class="loading">
                        <img src='https://www.e-learn.cn/qa/static/css/default/loading.gif' align='absmiddle' />
                         加载中...
                        </li>
                    </ul>
                </div>
          </li>
          	          
   <div style="text-align: center">
          <div class="laypage-main">
     <strong>1</strong>
<a href="https://www.e-learn.cn/qa/q-1046685/2.html">2</a>
<a class="n" href="https://www.e-learn.cn/qa/q-1046685/2.html">下一页</a>
           
           </div>
        </div>
                <style>
   
.laypage-main a, .laypage-main span {
    display: inline-block;
}
        </style>                  </ul>
        
        <div class="layui-form layui-form-pane">
          <form id="huidaform"  name="answerForm"  method="post">
            
            <div class="layui-form-item layui-form-text">
              <a name="comment"></a>
              <div class="layui-input-block">
            
    
<script type="text/javascript" src="https://www.e-learn.cn/qa/static/js/neweditor/ueditor.config.js"></script>
<script type="text/javascript" src="https://www.e-learn.cn/qa/static/js/neweditor/ueditor.all.js"></script>
<script type="text/plain" id="editor"  name="content"  style="width:100%;height:200px;"></script>                                 
<script type="text/javascript">
                                 var isueditor=1;
            var editor = UE.getEditor('editor',{
                //这里可以选择自己需要的工具按钮名称,此处仅选择如下五个
                toolbars:[['source','fullscreen',  '|', 'undo', 'redo', '|', 'bold', 'italic', 'underline', 'fontborder', 'strikethrough', 'removeformat', 'formatmatch', 'autotypeset', 'blockquote', 'pasteplain', '|', 'forecolor', 'backcolor', 'insertorderedlist', 'insertunorderedlist', 'selectall', 'cleardoc', '|', 'rowspacingtop', 'rowspacingbottom', 'lineheight', '|', 'customstyle', 'paragraph', 'fontfamily', 'fontsize', '|', 'indent', '|', 'justifyleft', 'justifycenter', 'justifyright', 'justifyjustify', '|', 'link', 'unlink', 'anchor', '|', 'simpleupload', 'insertimage', 'scrawl', 'insertvideo', 'attachment', 'map', 'insertcode', '|', 'horizontal', '|', 'preview', 'searchreplace', 'drafts']],
            
                initialContent:'',
                //关闭字数统计
                wordCount:false,
                zIndex:2,
                //关闭elementPath
                elementPathEnabled:false,
                //默认的编辑区域高度
                initialFrameHeight:250
                //更多其他参数，请参考ueditor.config.js中的配置项
                //更多其他参数，请参考ueditor.config.js中的配置项
            });
                        editor.ready(function() {
            	editor.setDisabled();
            	});
                            $("#editor").find("*").css("max-width","362px");
        </script>              </div>
            </div>
                          
    

        
         <div class="layui-form-item">
                <label for="L_vercode" class="layui-form-label">验证码</label>
                <div class="layui-input-inline">
                  <input type="text"  id="code" name="code"   value="" required lay-verify="required" placeholder="图片验证码" autocomplete="off" class="layui-input">
                </div>
                <div class="layui-form-mid">
                  <span style="color: #c00;"><img class="hand" src="https://www.e-learn.cn/qa/user/code.html" onclick="javascript:updatecode();" id="verifycode"><a class="changecode"  href="javascript:updatecode();"> 看不清?</a></span>
                </div>
              </div>
                                  <div class="layui-form-item">
                    <input type="hidden" value="1046685" id="ans_qid" name="qid">
   <input type="hidden" id="tokenkey" name="tokenkey" value=''/>
                <input type="hidden" value="ngModel for textarea not working in angular 2" id="ans_title" name="title"> 
             
              <div class="layui-btn    layui-btn-disabled"  id="ajaxsubmitasnwer" >提交回复</div>
            </div>
          </form>
        </div>
      </div>
      <input type="hidden" value="1046685" id="adopt_qid"	name="qid" /> 
      <input type="hidden" id="adopt_answer" value="0"	name="aid" />
    </div>
    <div class="layui-col-md4">
          
 <!-- 热门讨论问题 -->
     
 <dl class="fly-panel fly-list-one">
        <dt class="fly-panel-title">热议问题</dt>
            <!-- 本周热门讨论问题显示10条-->