title: Undefined method `json' for #<ActiveRecord:
body: <p>I have a create_table migration that looks like this:</p>
  
  <pre class="lang-html prettyprint-override"><code>class CreateOrders &lt; ActiveRecord::Migration[5.1]
    def change
      create_table :orders do |t|
        t.string :state
        t.string :coin_sku
        t.monetize :amount, currency: { present: false }
        t.json :payment
  
        t.timestamps
      end
    end
  end
  </code></pre>
  
  
  
  <p>Now when I run my rails db:migrate, it returns me an error message saying:</p>
  
  <pre class="lang-html prettyprint-override"><code>rails aborted!
  StandardError: An error has occurred, this and all later migrations canceled:
  
  undefined method `json' for #&lt;ActiveRecord::ConnectionAdapters::SQLite3::TableDefinition:0x007f819fbb81b8&gt;
  Did you mean?  JSON
  </code></pre>
  
  
  
  <p>Has anyone ever had this problem before? Many thanks!!</p>