mongo c-driver bcon $ne value no equal

Question

I am trying to append a requirement to my BCON query where 'tribe_type' does not equal 'initial-public'.

My original code was and that worked:

 query = BCON_NEW ("_id", BCON_OID(&oid));

When I add the second part, it compiles, however the mongo match fails.

        query = BCON_NEW ("_id", BCON_OID(&oid),
            "{",
                "tribe_type",
                "$ne",
                "initial-public",
            "}"
        );

score 1 · Accepted Answer · answered Feb 15 '17 at 21:19

You have to specify the BCON type for UTF-8 strings.
Be careful with implict $and's Be careful with nested documents and BCON.

    query = BCON_NEW ("_id", BCON_OID(&oid),
        "{",
            "tribe_type",
            "$ne",
            "initial-public",
        "}"
    );

compiles into this command

 { "_id" : <an oid> }, { "tribe_type" : "$ne" }

which is obviously not what you want.

be explicit with the $and operation, correctly type the string as a UTF8 field, and make sure you capture the nested documents like this:

query = BCON_NEW (
                "$and", "[", "{", "_id", BCON_OID(&oid), "}",
                             "{", "tribe_type", "{", "$ne", BCON_UTF8 ("initial-public"), "}", "}","]"
                );

yields a query that looks like this

{ "$and" : [ { "_id" : <an oid> }, { "tribe_type" : { "$ne" : "initial-public" } } ] }

which is probably what you want.

Thank you very much for the explanation. While I did figure out a solution, yours is better and much more informative. Thanks :) — Steven Carlson, Feb 19 '17 at 13:02

score 0 · Answer 2 · answered Feb 14 '17 at 19:09

0

        query = BCON_NEW ("_id", BCON_OID(&oid),
            "tribe_type", 
                "{",
                    "$ne", BCON_UTF8 ("initial-public"),
                  "}");

answered Feb 14 '17 at 19:09

Steven Carlson

925
1
10
25

I did post the fully working code after I figured it out. – Steven Carlson Feb 19 '17 at 13:01

mongo c-driver bcon $ne value no equal

2 Answers2