MongoDB C++, failed to add an array to document

Question

When adding an array to document, open_array and close_array must come at the same time when throwing into the document stream. The follow code fails (compile time) at the last line when adding 'close_array'.

vector<string> List;
...

document Doc;
Doc <<"List" <<open_array;
for (string Str: List) {
  Doc <<Str;
}
Doc <<close_array;

But I don't know the number of elements in the 'List' to add to document at the same time. MongoDB still lacks examples for the C++ driver.

This code works but the number of items in the 'List' is not known.

Doc 
<<open_array
<<List[0] <<List[1] <<List[2] <<...
<<close_array;

G++ error:

content.cpp:65:7: error: no match for ‘operator<<’ (operand types are ‘bsoncxx::v_noabi::builder::stream::document’ and ‘const bsoncxx::v_noabi::builder::stream::close_array_type’)
   Doc <<close_array;
   ~~~~^~~~~~~~~~~~~
compilation terminated due to -Wfatal-errors.

score 0 · Accepted Answer · edited May 23 '17 at 12:13

0

Found a solution from Adding a BSON Array to a MongoDB 3.2 document and extracting the values back ( MongoCXX 3.2 ) ( C++ 11)

It's not able to add the 'close_array' to the document itself, it must be added thru' an array builder (type 'auto', I didn't dig it out to find the real type).

auto Array = Doc <<"List" <<open_array;
for (string Str: List) 
  Array <<Str;
Array <<close_array;

To be noted that the above code works fine, but the following won't

auto Array = Doc <<"List";
Array <<open_array;
for (string Str: List) 
  Array <<Str;
Array <<close_array;

edited May 23 '17 at 12:13

Community

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answered Nov 30 '16 at 09:58

Dee

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i build mongodb c++ driver 3.1.0 from https://github.com/mongodb/mongo-cxx-driver/archive/r3.1.0.tar.gz – Dee Dec 18 '16 at 16:05
building array like in the code in my answer works fine – Dee Dec 18 '16 at 16:05
There is actually a better answer, i should add it ;) – Oliver Dec 18 '16 at 17:01

MongoDB C++, failed to add an array to document

1 Answers1