CouchDB按链接的文档属性排序

Question

I have the following data:

payment1: {
    id: "payment1",
    categoryId: "category1"
}

payment2: {
    id: "payment2",
    categoryId: "category2"
}

payment3: {
    id: "payment3",
    categoryId: "category2"
}

category1: {
    id: "category1",
    name: "Food"
}

category2: {
    id: "category2",
    name: "Leisure"
}

What I need is a view for sorting the payment data by category NAME. Is it possible in CouchDB?

Thanks in advance! Ivan

Answer 1

What is possible is a bit different from what you want.

Here is the map:

function (o) {
  if (o.categoryId) {
    emit(o.categoryId);
  } else {
    emit(o.id);
  }
}

You'll call it with /mydb/_design/mydesign/_view/myview?include_docs=true and get:

{"rows":[
   {"key":"category1", "doc":{"id":"payment1","categoryId":"category1"},
   {"key":"category1", "doc":{"id":"category1","name":"Food"},
   {"key":"category2", "doc":{"id":"payment2","categoryId":"category2"},
   {"key":"category2", "doc":{"id":"payment3","categoryId":"category2"},
   {"key":"category2", "doc":{"id":"category2","name":"Leisure"}
]}

In other words, payments are grouped by category, they are also joined with category's name. However, they are sorted according category ID but not category's name.

What you want would require two different sorts (ie "chained map reduce").