title: React | DataGrid does not update with changed State
body: <p>I am currently working on a linktree using the Datagrid Component from MaterialUI.
  Data can be displayed, but when I try to add a new entry there occurs the problem that the content remains the same. The state changes, but without rendering the new data.</p>
  <pre><code>const columns = [
  {field: 'date', headerName: 'Date', width: 120},
  {
      field: 'videoUrl',
      headerName: 'Video URL',
      width: 430,
      renderCell: (params) =&gt;
              &lt;a href={(params.value)}&gt;{params.value}&lt;/a&gt;
  },
  {field: 'description', headerName: 'Description', width: 130},
  ];
  
  
  class Linktree extends React.Component {
      this.state = {
          newLink: &quot;&quot;,
          newDescription: &quot;&quot;,
      }
  }
  
  handleAddNewLink(newLink, description) {
      let obj = this.state.linksData
      let newEntry = {id: this.state.linksData.length+1, postDate: today, videoUrl: newLink, description: description}
      obj.push(newEntry)
  
      this.setState({linksData: obj})
  }
  
  render (){
      return (
          &lt;div&gt;
              &lt;div style={{height: 400, width: '100%', backgroundColor: &quot;white&quot;}}&gt;
                  &lt;DataGrid rows={!this.state.loading ? this.state.linksData : []} columns={columns} pageSize={5} hideFooterSelectedRowCount/&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      );
  }}
  </code></pre>