Filter couchdb document based on value from nested child document

0
votes

I would like to create a map/reduce function that filters the documents based on a nested value from the child document. But retrieve the parent document.

I have following documents: 

{
   "_id": "1",
   "_rev": "1-991baf1d86435a73a3460335cc19063c",
   "configuration_id": "225f9d47-841c-43c2-90c2-e65bb49083d3",
   "name": "test",
   "image": "",
   "type": "A",
   "created": "",
   "updated": 1,
   "destroyed": ""
}

{
   "_id": "225f9d47-841c-43c2-90c2-e65bb49083d3",
   "_rev": "1-3e3a1c357c86cbd1cd42b5980b9655a4",
   "configuration_packages_id": "cd19b0ba-157d-4dd4-adac-56fd470bfed4",
   "configuration_distribution_id": "5b538411-ca99-46c7-ac3c-1f382e4577a9",
   "type": "CONFIGURATION",
   "configuration": {
       "hostname": "example123",
       "images": [
           "image1",
           "image2"
       ]
   }
}

Now I would like to retrieve all the documents of type A and with hostname example123.

At the moment I retrieve all the document of type A like this:

function (doc) {
            if (doc.type === "A") {
                emit([doc.updated], doc);
            }
        }

But now I would also like to filter on the host name as well. I'm not sure on how to achieve this with CouchDB.

1
couchdbpouchdb

1 Answers

3
votes

TLDR;

You cannot do this

Details

Your "nested" document is only accessible through a join but you can't query it.

The correct way to do that kind of query natively would have been to have a real nested document inside the parent document. Separating those documents has a cost.

Join example

function (doc) {
    if (doc.type === "A") {
        emit([doc.updated,0]);
        emit([doc.updated,1],["_id":doc.configuration_id]);
    }
}

If you query the view with "include_docs=true", this will get you the configuration document linked as well as the parent document itself. Then you can query to get the updated docs, merge the nested(1) with the parents(0) and filter them.