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  1. Core Server
  2. SERVER-9693

Impossible to select a subdocument with blank field name ( "" )

    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Minor - P4 Minor - P4
    • None
    • Affects Version/s: 2.4.3
    • Component/s: Querying, Shell
    • Labels:
    • Environment:
      Possibly all.
    • ALL
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      1. Insert (e.g. through pymongo) a document containing a subdocument with an empty key field.
      2. Try to query the specific field (the one with "" key).
      3. Try to rename the specific key.

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      1. Insert (e.g. through pymongo) a document containing a subdocument with an empty key field. 2. Try to query the specific field (the one with "" key). 3. Try to rename the specific key.

      Situation: some MongoDB documents have subdocuments that contain an empty key, e.g. (I stripped ObjectIDs to make the code look nicer):

      { 
          "_id" : ObjectId("..."), 
          "stats" : 
              { 
                  "violations" : 0, 
                  "cost" : 170, 
              }, 
          "parameters" : 
              { 
                  "" : "../instances/comp/comp20.ectt", 
                  "repetition" : 29, 
                  "time" : 600000 
              }, 
          "batch" : ObjectId("..."), 
          "system" : "Linux 3.5.0-27-generic", 
          "host" : "host3", 
          "date_started" : ISODate("2013-05-14T16:46:46.788Z"), 
          "date_stopped" : ISODate("2013-05-14T16:56:48.483Z"), 
          "copy" : false
      }
      

      The problem is line:

      "" : "../instances/comp/comp20.ectt"

      it is impossible to get back the value of the field. Querying doesn't work:

      db.experiments.find(

      {"batch": ObjectId("...")}

      ,

      { "parameters.": 1 }

      )

      gets the full content of the parameters subdocument. (My guess is that "." is probably ignored if followed by an empty selector.) From the JSON specification (15.12.*) it looks like empty keys are allowed.
      Moreover, renaming doesn't work either, for similar reasons.

            Assignee:
            Unassigned Unassigned
            Reporter:
            tunnuz Tommaso Urli
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              Created:
              Updated:
              Resolved: