title: How to iterate through a map of Objects in Flutter
body: <p>I have this data as json:</p>
  
  <pre><code>{
     "id":1,
     "value":"value x",
     "option":{
        "id":1,
        "name":"option d"
     },
     "attachment":null,
     "price":0
  },
  {
     "id":2,
     "value":"value y",
     "option":{
        "id":1,
        "name":"option b"
     },
     "attachment":null,
     "price":0
  },
  </code></pre>
  
  <p>I wanted to view them as ListView after grouping them with Option.name so the return is a map as:</p>
  
  <pre><code>Map&lt;String, List&lt;Option&gt;&gt; getGrouped(
        List&lt;Option&gt; options) {
      Map&lt;String, List&lt;Option&gt;&gt; groupByData = groupBy(
          itemVariations, (obj) =&gt; (obj as Option).option.name);
      return groupByData;
    }
  </code></pre>
  
  <p>I am not how can this be viewed as a nested Text() widget?
  I tried many things and its always:</p>
  
  <pre><code>The argument type 'List&lt;Option&gt;' can't be assigned to the parameter type 'String'.
  </code></pre>