Construct query filter using the C API

[pjc]

Hi

I am new to using the C API for mongoldb.

Need to construct a query filter using the C API programmatically as I build the string based on values passed to my program.

The filter using the mongo shell is: db.example.find( {"city": { $gte: "London" }} ) which works fine.

I tried this in the C API:

        bson_t* query = BCON_NEW("filter");

BCON_APPEND(query, "{");

BCON_APPEND(query, "city");

BCON_APPEND(query, "{");

BCON_APPEND(query, "$gte");

BCON_APPEND(query, "London");

BCON_APPEND(query, "}");

BCON_APPEND(query, "}");

However the api calls fail with an assert.

I also tried: 

   bson_t* query = BCON_NEW(BCON_UTF8(" {"city": { $gte: "London" }} )"));

Anybody have any ideas? 

[A. Jesse Jiryu Davis]

We have a BCON tutorial here:

http://mongoc.org/libmongoc/current/tutorial.html#using-bcon

for your example, do:

bson_t *query = BCON_NEW ("filter", "{", "city", "{", "$gte", BCON_UTF8 ("London"), "}", "}");

Field names and delimiters like "{" and "}" are simple strings, values like "London" are wrapped in a BCON macro.