Cloudant query to return records where 2 fields are equal

问题

I can search for specific values for fields. How can I search for fields equal to other fields? For example,

I have docId and parentDocId; how do I search for records that have docId == parentDocId?

query to search for specific id which equals "123":

let query = ["parentDocId": ["$eq":"123"]]
let result = datastore.find(query, skip: 0, limit: 0, fields: nil, sort: nil)

I would like to search where parentDocId == docId.

Any ideas?

p.s. I am using Swift

回答1:

There's no need to use Cloudant Query. Assuming your docs have the following structure

{
 "_id": "2b7946de457b6fc9af3e3d29faa3fcba",
 "_rev": "3-088f847ef010504e7a5beb0c821d72ea",
 "parentDocId": "2b7946de457b6fc9af3e3d29faa3fcba",
 ...
}

you can create a view like this

PUT https://$USERNAME:$PASSWORD@$HOST/$DATABASE/_design/demo HTTP/1.1
Content-Type: application/json

 {
  "views": {
  "parent_child": {
   "map": "function (doc) {\n  if(doc._id === doc.parentDocId) {\n    emit(doc._id, 1);\n  }\n}"
   }
  }
 }

and query it:

GET https://$USERNAME:$PASSWORD@$HOST/$DATABASE/_design/demo/_view/parent_child HTTP/1.1

All client libraries should support views since they are a fundamental concept in CouchDB/Cloudant. I'm not familiar with Swift but the library documentation should identify the appropriate method you need to invoke to make a call that's equivalent to the general HTTP one I listed.

来源：https://stackoverflow.com/questions/42735442/cloudant-query-to-return-records-where-2-fields-are-equal