Mongo Query on Subfields

Question

I have a document -

  {\"_id\" : ObjectId(\"51385d2308d427ce306f0100\"),
  \"aid\" : \"1\",
  \"studyId\" : \"study-1\",
  \"mediaType\" : \"mic         


        

Answer 1

you could use mapReduce() where the map() function would contain something like:

// loop all key/value pairs in status without knowing its key
for ( item in this.status ) {
    // if value is required: emit the data and break the loop
    if ( this.status[item] == "required" ) {
        emit( ... )
        break;
    }
}

does this help ?

Cheers

Ronald

Answer 2

u could search via db.foo.find({ 'status.algo1' : 'required' }) or db.foo.find({ 'status.algo2' : 'required' }), but it's probably not possible to filter by regex keys, see also this post: https://stackoverflow.com/a/7290728/654952

Answer 3

Another, more efficient, approach would be to implement your "status" sub-document as an array of "typed values", like this:

 {"_id" : ObjectId("51385d2308d427ce306f0100"),
  "aid" : "1",
  "studyId" : "study-1",
  "mediaType" : "microBlog",
  "text" : "bla bla",
  "sentences" : "bla bla",
  "status" : [
          { type: "algo1", value: "required" },
          { type: "algo2", value: "required" },
          { type: "algo3", value: "completed" },
          { type: "algo4", value: "completed" }
  ],
  "priority" : "u"}

This would allow you to find all the documents, for which any of the sub-field has value "required", with this query:

db.foo.find({"status.value":"required"})

Defining an index on this sub-field would speed up the query:

db.foo.ensureIndex({"status.value":1})