title: sequelize where relation is null
body: <p>I have an issue with sequelize. Here is what I'm trying to do:</p>
  
  <pre><code>return pointsTransaction.findAndCountAll({
      where:{
          user_id: userId
      },
      limit: opts.limit,
      offset: opts.offset,
      include:[{
          model:sequelize.models.pointsPendingtransaction
      }]
  });
  </code></pre>
  
  <p>The generated query looks like that:</p>
  
  <pre><code>SELECT "pointsTransaction".*,
  "pointsPendingtransactions"."transaction_ptr_id" AS "pointsPendingtransactions.transactionPtrId",
  "pointsPendingtransactions"."is_active" AS "pointsPendingtransactions.isActive",
  "pointsPendingtransactions"."transaction_id" AS "pointsPendingtransactions.transaction_id" 
  FROM (
  SELECT "pointsTransaction"."id",
  "pointsTransaction"."date_time" AS "dateTime",
  "pointsTransaction"."details",
  "pointsTransaction"."points",
  "pointsTransaction"."user_id" 
  FROM "points_transaction" AS "pointsTransaction" 
  WHERE "pointsTransaction"."user_id" = 10002 LIMIT 1000
  ) AS "pointsTransaction" 
  LEFT OUTER JOIN "points_pendingtransaction" AS "pointsPendingtransactions" 
  ON "pointsTransaction"."id" = "pointsPendingtransactions"."transaction_id"
  </code></pre>
  
  <p>So in SQL I would just need to add that line at the end of my query to make it work: <code>WHERE "pointsPendingtransactions"."transaction_id" IS null</code></p>
  
  <p>So my question is, how can I do that with sequelize? I tried many different ways but no one worked...</p>