title: How to disable a specific input field in ngFor based on another field value
body: <p>Sorry if this is a stupid questions, I am new to Angular. I did a search on this, but couldn't find a similar question. Please let me know if this is duplicated. </p>
  
  <p>I have a data set like the following</p>
  
  <pre><code>    {{country: "Canada";
        city: "Toronto";
        weather: {
        {date: "06JUL2018"
            temp: 26;
            rain: "3mm";},
        {date: "07JUL2018"
            temp: 24;
            rain: "0mm";}
        {date: "08JUL2018"
            temp: 28;
            rain: "0mm";}......}
      },
      {country: "Canada";
        city: "Vancouvr";
        weather: {
        {date: "06JUL2018"
            temp: 31;
            rain: "0mm";},
        {date: "07JUL2018"
            temp: 23;
            rain: "0mm";}
        {date: "08JUL2018"
            temp: 21;
            rain: "0mm";}......}
      },........
      }
  </code></pre>
  
  <p>in my html i have</p>
  
  <pre><code>    &lt;form *ngFor='let data of dataList'&gt;
        &lt;fieldset&gt;
          &lt;legend&gt;{{ data.country }} - {{data.city}} &lt;/legend&gt;
          &lt;ng-container *ngFor='let wDetails of data.weather' &gt;
            &lt;label &gt;{{ wDetails.date }}:&lt;/label&gt;  
            &lt;select name={{wDetails.rain}} value={{wDetails.rain}} (ngModel)="flag"&gt;
              &lt;option value="Yes"&gt;Yes&lt;/option&gt;
              &lt;option value="No"&gt;No&lt;/option&gt;
            &lt;/select&gt;
            &lt;input type="text" name={{wDetails.volume}} value={{wDetails.volume}} [disabled]="flag"&gt;
          &lt;/ng-container&gt;
        &lt;/fieldset&gt;
      &lt;/form&gt;
  </code></pre>
  
  <p>I made some changes to the data and code to hide sensitive information from work, but the idea is the same. </p>
  
  <p>What i am trying to do is have the <strong>wDetails.volume</strong> input field disabled based on the <strong>wDetails.rain</strong> field value for that city. If the user change <strong>wDetails.rain</strong>  from 'yes' to 'no' for Toronto, then the <strong>wDetails.volume</strong> for Toronto should be disabled, and Vancouver one should still be enable. </p>
  
  <p>When i do it in my way, the value <strong>wDetails.rain</strong> become empty on the page, and when i change it, it disable ALL the <strong>wDetails.volume</strong> input field.</p>
  
  <p>Thanks in advance </p>