How to find by attribute starting with $

Question

I try to query couchdb server with _find endpoint by attribute, starting with '$' ($ref in my case). But server always returns empty document set.

I have couchdb documents like this:

{
  "_id": "59bb208006149f50bb32f76f4900ccfa",
  "_rev": "1-99022821cc2bb3ab0bdd84ab98b55828",
  "contents": {
    "eClass": "auth#//User",
    "name": "SuperAdminUser",
    "roles": [
      {
        "eClass": "auth#//Role",
        "$ref": "59bb208006149f50bb32f76f4900c962?rev=1-24d9469afe50f162e473b09fdbd95154#/"
      }
    ],
    "email": "admin@mydomain.ru",
  }
}

I try to query this document like this:

{
    "contents": {
        "eClass": "auth#//User",
        "roles": {
            "$elemMatch": {
                "eClass": {"$regex": ".*auth#//Role"},
                "$ref": {"$regex": "^59bb208006149f50bb32f76f4900c962.*"}
            }
        }
    }   
}

but no results returned.

Query like

{
    "contents": {
        "eClass": "auth#//User",
        "roles": {
            "$elemMatch": {
                "eClass": {"$regex": ".*auth#//Role"}
            }
        }
    }   
}

works as expected.

It seems the mango server did not recognize attributes like $ref.

I tried to escape attribute with "\$ref" with no success. (not true!!!, see update)

Is there any workarounds to query such attributes like $ref?

I think that is currently not possible, there exists an open issue for this: https://github.com/apache/couchdb/issues/2028 — uminder, Jul 15 '19 at 08:29
Possible duplicate: https://stackoverflow.com/q/55976271/13860 — Jonathan Hall, Jul 15 '19 at 09:38
this is definitly duplicate, sorry. thanks for pointing the issue — Oleg Orlov, Jul 15 '19 at 10:39
Does this answer your question? [How to define a \_find query in couchdb mango with field names that start with dollar sign ($)](https://stackoverflow.com/questions/55976271/how-to-define-a-find-query-in-couchdb-mango-with-field-names-that-start-with-do) — Jonathan Hall, Jan 03 '20 at 21:45
@OlegOrlov: Do not put answers in your question. Please provide your own answer instead, below. — Jonathan Hall, Jan 08 '20 at 22:18

score 0 · Answer 1 · answered Jan 08 '20 at 22:18

Note: OP provided this answer as an update to the question. I've moved it here to conform to site standards.

This query works.

{
   "selector": {
      "contents": {
         "eClass": "auth#//User",
         "roles": {
            "$elemMatch": {
               "eClass": {
                  "$regex": ".*auth#//Role"
               },
               "\\$ref": {
                  "$regex": ".*59bb208006149f50bb32f76f4900c962.*"
               }
            }
         }
      }
   }
}

So just use "\\$ref" escape style.

How to find by attribute starting with $

1 Answers1

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