如何在mongodb中映射三个集合

Question

我在monogdb中有三个集合。如何映射三个集合。我尝试了一下，但是它不起作用可以给出一些代码或示例。

Group_promotion.collection

[
{
  "id":1,
   group_name:"Latest",
   products_id:[10,20]
}]

产品集合

[
{
  "id":10,
   product_name:"bourbon",
   category_id:20
},{
  "id":20,
   product_name:"cream",
   category_id:20
}]

Category.collection

[
{
  "id":20,
   name:"beat"
}]

例外的食物

[
{
  "id":1,
   group_name:"Latest",
   products_id:[
{
  "id":10,
   product_name:"bourbon",
   name:"beat"
},{
  "id":20,
   product_name:"cream",
   name:"beat"
}]
}]