Array on firebase - RealTime

Good morning, I'm developing an application with ionic 3 and firebase. Until then, the app does query, delete, and write data. The problem: The app writes information, but my need is to write a list of products, but I'm having problems. Here is the code:

this.db.database.ref(userId)
      .push({ 
      dataPag: pedido.dataPag,
      tipo: pedido.tipo,
      qtde: pedido.qtde,
      pv: pedido.pv,
      desc: pedido.desc,
      valTot: pedido.valTot,
      cliente: pedido.cliente,
      produto: pedido.vetorProduto,
      total: pedido.total,
      formaPag: pedido.formaPag

     })
      .then(() => resolve());