title: DynamoDB update list of list items
body: <p>I need your help to update/add item in a list of list of DynamoDB.</p>
  
  <p>I want to add and update a list that is composed by a list. 
  How can i do that? Thanks for your help</p>
  
  <p><strong>Here my example:</strong></p>
  
  <p><strong><em>DATABASE</em></strong></p>
  
  <pre><code>Item{1}
         idProject:"15azeze-55ze"
         dateCreationProjectString:   08/01/2018 14:6:32  
         environnements:    List[1]   
            0 MAP {3}
                idEnvironnement: "11-aa",
                name:"Exemple Environnement"
                tasks[0]
  </code></pre>
  
  <p><strong><em>NodeJS code :</em></strong></p>
  
  <pre><code>let newTask =  {
     authorTask :      "Toto",
     dateCreationTask: "01/01/1960",
     idTask:           "154-141-aa41",
     nameTask:         "Task name ..."
  };
  
  
  
  dynamodbdc.update({
      TableName: "projects",
      Key: { idProject: "15azeze-55ze", idEnvironnement:"11-aa" },
      ReturnValues: 'ALL_NEW',
      UpdateExpression: 'set #environnements.#tasks = list_append(if_not_exists(#environnements.#tasks, :empty_list), :newTask)',
      ExpressionAttributeNames: {
        '#environnements' : 'environnements',
        '#tasks'          : 'tasks',
      },
      ExpressionAttributeValues: {
        ':newTask': [newTask],
        ':empty_list': []
      }
    }, function(error, stdout) {
            if(error){
              console.log("error==", error)                
            else {            
               console.log("Nice thank you !!")
            } 
    });
  </code></pre>