title: Add an unknown number of strings to DynamoDB
body: <p>In my PHP script, I get a POST reaction from an HTML form. One of the texts, is a list of things, separated by a comma (for example: <code>"apple, banana, orange"</code>).</p>
  
  <p>I want to upload this text, among with other texts which got POSTed to a table on Amazon DynamoDB, but I don't want to upload it as a string, but as a string set (for example: <code>["apple", "banana", "orange"]</code>).</p>
  
  <p>Now, I know how to split the string:</p>
  
  <pre><code>$list = "apple, banana, orange";
  $fruits = explode(", ", $list);
  echo $fruits[0]; // apple
  echo $fruits[1]; // banana
  echo $fruits[2]; // orange
  </code></pre>
  
  <p>And, I also know how to upload a string array to DynamoDB:</p>
  
  <pre><code>$sdk = new Aws\Sdk([
      'region'   =&gt; 'us-west-2',
      'version'  =&gt; 'latest'
  ]);
  
  $dynamodb = $sdk-&gt;createDynamoDb();
  
  $response = $dynamodb-&gt;putItem([
      'TableName' =&gt; 'ProductCatalog',
      'Item' =&gt; [
          'Id'       =&gt; ['N'      =&gt; '104'      ], // Primary Key
          'Title'    =&gt; ['S'      =&gt; 'Book 104 Title' ],
          'ISBN'     =&gt; ['S'      =&gt; '111-1111111111' ],
          'Price'    =&gt; ['N'      =&gt; '25' ],
          'Authors'  =&gt; ['SS'  =&gt; [$authorA, $authorB] ]
                  ]
  ]);
  </code></pre>
  
  <p>But, how to upload the strings, if I don't know the exact number?</p>
  
  <p>If I knew the number of items then it would be like:</p>
  
  <pre><code>'Fruits' =&gt; ['SS' =&gt; [$fruits[0], $fruits[1], $fruits[2]]
  </code></pre>
  
  <p>But the problem is that I don't know.<br>
  How can I upload the string array to DynamoDB although I don't know the exact number of strings in the array?</p>