title: How do I block undefined variables from being sent on Postman?
body: <p>I'm using Postman to run test on an API using a CSV file as an external file data. In the CSV file, there are multiple data sets with different amount of data, some with data and some without. When I run collection runner and it runs the first data set, it fails because there are variables that have not been defined and the API throws a data error.</p>
  
  <p>In the CSV</p>
  
  <ol>
  <li><p>Data set 1</p>
  
  <ul>
  <li>order,
  clientid,
  barcode 1,
  quantity 1,
  unitprice 1</li>
  </ul></li>
  <li><p>Data set 2</p>
  
  <ul>
  <li>order,
  clientid,
  barcode 1,
  quantity 1,
  unitprice 1,
  barcode 2,
  quantity 2,
  unitprice 2</li>
  </ul></li>
  <li><p>Data set 3</p>
  
  <ul>
  <li>order,
  clientid,
  barcode 1,
  quantity 1,
  unitprice 1,
  barcode 2,
  quantity 2,
  unitprice 2,
  barcode 3,
  quantity 3,
  unitprice 3</li>
  </ul></li>
  </ol>
  
  <pre><code>In the body I've added that extra variables in case it is available in a data set.
  
  {
    "order"  :  "{{orderId}}",
    "clientId" : "{{clientId}}",
    "skus"  :  [
          {
              "barcode": {{barcode1}},
              "quantity": {{quantity1}},
              "unitPrice": {{price1}}
          },
           {
              "barcode": {{barcode2}},
              "quantity": {{quantity2}},
              "unitPrice": {{price2}}
          },
           {
              "barcode": {{barcode3}},
              "quantity": {{quantity3}},
              "unitPrice": {{price3}}
          }
      ]
  
  }
  </code></pre>
  
  <p>This is the response: </p>
  
  <pre><code>{
   "order" : "1000305408",
   "clientId" : "30",
   "skus" : [
   {
   "barcode": 123123123,
   "quantity": 1,
   "unitPrice": 100
   },
   {
   "barcode": {{barcode2}},
   "quantity": {{quantity2}},
   "unitPrice": {{price2}}
   }
   ]
  } 
  </code></pre>
  
  <p>Is there a way to block those undefined variable key and data while still having it in the body just in case the new data set has the variable?</p>