CODEWITHSUNDEEP
couchdb
Miji
Miji

Reputation: 3

How to pull embedded 1:1 data on a CouchDb document

I am using CouchDb to store my documents and figuring out how to pull 1:1 related data on a document using CouchDb views.

For this given document structure,

{
  _id: 'some_id',
  doc_type: 'item',
  name: 'Steel Caliper'
  description: 'Steel Caliper description',
  classification: {
    _id: 'some_classification_id'
  }
}

classification: {
  _id: 'some_classification_id',
  doc_type: 'classification',
  name: 'Hand Tools'
}

When I retrieve a list of item documents using a CouchDb view like below (called with include_docs=true)

function(doc) {
  if(doc_type==='item') {
     emit(doc.name, null);
  }
}

I get the item document but without the classification data pulled in. 

{
  "total_rows": 10,
  "offset": 0,
  "rows": [
    {
      "id": "some_id",
      "key": "Steel Caliper",
      "value": null,
      "doc": {
        "_id": "some_id",
        "_rev": "1-65d32fe22a0b949ff73f23c65042ae3c"
        "doc_type": "item"
        "name": "Steel Caliper"
        "classification": {
          "_id": "some_classification_id"
        }
      }
    },
    { ... }
}

Is there a way to pull in the classification data using a view and get an output like below ?

...
    "doc": {
       "_id": "some_id",
       "_rev": "1-65d32fe22a0b949ff73f23c65042ae3c"
       "doc_type": "item"
       "name": "Steel Caliper"
       "classification": {
          "_id": "some_classification_id",
          "doc_type": "classification",
          "name": "Hand Tools"
       }
    }
...

Upvotes: 0

Views: 71

Answers (1)

Weijian
Weijian

Reputation: 174

yes, this is called view collation. You can emit multiple docs if you are joining by _ids.

in your case you can call

function(doc) {
   if(doc_type==='item') {
     emit(doc.name, null);
     if( doc.classification ){
         emit( doc.classification._id, {_id: doc.classification._id });
     }

   }
}

you might still need play around with the returned result to get it into the form you want.

http://docs.couchdb.org/en/2.0.0/couchapp/views/joins.html

Upvotes: 1

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