title: Sequelize Upsert without primary key value in arguments
body: <p>So, I have a relation which has the autogenerated <code>id</code> as the primary key and I want it to be that way.</p>
  
  <p>The issue is that whenever I call <code>upsert()</code>, it seems like I have to provide for the primary key value as well in the parameter object which is insane as I wouldn't know what is the <code>id</code> of the particular row I want to edit. </p>
  
  <p>Instead, I am sending mandatorily the value for a <code>unique</code> key that I have defined, but it doesn't work.</p>
  
  <p>Any workarounds or do I need to shift my primary key to some other key of whose value is known?</p>
  
  <blockquote>
    <p>Example:  Let's say I have an <code>Employee</code> table where I have the Employee Id as the PK and their emails as the UNIQUE key. Now, I believe that an <code>upsert</code> operation can still be carried out using a unique key, but that doesn't seem to be possible and I have to tag in the primary key for it.</p>
  </blockquote>